Alison Butler - US grants

The goal of this award is to elucidate the reactivities and mechanisms of two newly discovered haloperoxidase metalloenzymes, a vanadium bromoperoxidase (V-BrPO) and a non-heme iron (III) bromoperoxidase (FeNH-BrPO) which are both isolated from marine algae. V-BrPO and FeNH-BrPO are the first non-heme haloperoxidases to be discovered. Experiments are planned to test whether each metal ion functions as a Lewis acid catalyst or as an electron transfer catalyst, shuttling between different oxidation states. Both V-BrPO and FeNH-BrPO catalyze the bromination of pyrimidine- containing nucleic acids, cytosine and uracil. The reactivities of the two enzymes will be studied in terms of a) the types of organic compounds that can be brominated, b) the catalase and superoxide dismutase activity of the enzymes and c) the mechanism of reoxidation of the reduced derivatives of the enzymes. Halogenated organic compounds occur widely in marine organisms. Some of them have exciting biological activity. They represent a valuable, but neglected natural resource. The proposed research will help us understand how the myriad halogenated compounds are formed.

The goal of this work is to improve our understanding of the biological function of vanadium, in general, and to investigate the reactivity of vanadium-containing proteins, more specifically. Vanadium is capable of existing in many oxidation states and the aqueous chemistry of vanadium is dominated by electron transfer, hydrolysis and/or polymerization reactions. Clearly the coordination environment of the vanadium will affect its reactivity. Towards our overall goal, we proposed to investigate the factors that govern the oxidation and reduction reactions of vanadium bound to macromolecules (eg., the naturally occurring V-bromoperoxidase and V substituted derivatives of transferrin, lactoferrin, ovotransferrin, carboxypeptidase A, carbonic anhydrase B, thermolysin, bleomycin, etc), and to examine the possibility that vanadium proteins catalyze the disproportionation of superoxide (i.e., superoxide dismutase activity), participate in the disproportionation of hydrogen peroxide (i.e., catalase activity) and/or halogenate certain organic substrates in the presence of H2O2 (i.e., haloperoxidase activity). We have found that several V(V) complexes catalyze the decomposition of hydrogen peroxide, including V2-transferrin, V(V)-(8- hydroxyuinoline)(O)(OCH3) and V(V)-desferoxamine. The later two are catalyzed by ultraviolet light. We also propose to further characterize the vanadium bromoperoxidase (V-BrPO) isolated from Ascophyllum nodosum and Laminaria setchellii. We have discovered that this enzyme brominates the pyrimidine-containing nucleic acid bases, cytosine and uracil. Experiments are proposed to probe the substrate specificity by variation of the pyrimidine-ring substituents. Experiments are also proposed to probe the function of the vanadium. Does the vanadium act as a Lewis acid catalyst or an electron transfer catalyst, cycling between oxidation states? These mechanistic studies will be further probed using the model complex, V(V)-desferoxamine, which we have shown catalyzes the same bromination reactions as the V-BrPO.

A three day symposium, entitled "Marine Bioinorganic Chemistry" will be held at the National American Chemical Society Meeting/4th Chemical Congress of North America, August 25-30, 1991 in New York City. The purpose of this symposium is to bring together biochemists, inorganic chemists, bioinorganic chemists, chemical and biological oceanographers and civil/environmental engineers to discuss the recent developments in the emerging field of marine bioinorganic chemistry. Many novel metalloenzymes, metal binding ligands, inorganic compounds and biomolecules. Because the transition metal composition of the ocean is now relatively well defined, the study of the bioinorganic chemistry of the oceans has now become feasible. By bringing together scientists from the fields listed above, this symposium is likely to stimulate new ideas, interests and collaborations in this emerging field.

The focus of this project is the reactivity of vanadium bromoperoxidase isolated from marine organisms (e.g., Ascophyllum nodosum, Fucus distichus Macrocystis pyrifera). The marine environment is a very rich source of halogenated and selectively oxidized metabolites, many of which have important biological activities (e.g., chemical defense,, antimicrobial), and applications as pharmaceuticals (antineoplastic, antiinflammatory, antifungal, antibacterial) and specialty chemicals (e.g., dyes). V-BrPO catalyzes the bromination of certain organic compounds and the oxidation of others. The PI has shown that in the absence of a good substrate for bromination, V-BrPO catalyzes the formation of singlet oxygen. V-BrPO is not inactivated by high concentrations of singlet oxygen or oxidized bromine species, contrary to the behavior of the FeHeme haloperoxidases. The plan is to investigate the selectivity of bromination vs oxidation for important marine natural product precursors (e.g., indoles, furans, B-diketons and B-ketoacids), the kinetics and mechanism of bromination and oxidation. The mechanism of chloroperoxidase activity of the vanadium enzyme which the PI has recently discovered , will also be investigated. The non heme chloroperoxidase from the fungus Curvularia inaequalis will be studied, including determination of the active-site metal ion (e.g., likely to be iron, zinc or vanadium), the kinetics and mechanism of halogenation vs dioxygen formation, and the relative reactivity of oxidation vs halogenation.

The objectives of this research are to improve our understanding of vanadium in biological systems and our understanding of iron in the marine environment. In Part I we are focusing functional biomimetic studies of the essential vanadium ion in vanadium bromoperoxidase (vBrPO; an enzyme isolated from marine algae). V-BrPO is thought to be involved in the biosynthesis of the chiral halogenated and pseudohalogenated natural products, many of which have potent pharmacological activities. Dioxovanadium(V) is the first fully functional mimic of V-BrPO, catalyzing the oxidation of bromide by hydrogen peroxide which results in the formation of brominated organic substrates, or, in the absence of a substrate, the formation of dioxygen. The goal of Part I is to further elucidate the mechanism of the biomimetic system to understand the 10(4) difference in reactivity between V-BrPO it's optimum pH of ca. 6.5 and VO(O2)+ in 0.05 M acid. The approach is to investigate the reactivity of VO(O2)+, vanadium(V) complexes and other transition metal ions complexes towards halide oxidation by hydrogen peroxide, develop chiral halogenation reactions mediated by vanadium and other transition metals and investigate pseudohalogenation reactions mediated by the peroxovanadium(V) system. In Part II, we are focusing on the mechanisms of acquisition of iron (and other metal ions) by open ocean marine bacteria because the discrepancy between iron availability and requirements ranges between 2-5 orders of magnitude and because the transition metal composition of the oceans is extreme and unique. Molybdenum and vanadium are the two most abundant transition metal ions in surface seawater. All microorganisms, with the possible exception of lactobacilli, require iron for growth. It is surprising that so little is known about mechanisms of iron acquisition by marine microorganisms. We are focusing first on the structures of siderophores produced by marine bacteria to determine 1) whether these bacteria produce siderophores that complex iron more tightly than other siderophores, 2) whether their metal binding selectivity is different from terrestrial siderophores and 3) whether the metal uptake mechanisms (metal regulation, pathways, outer membrane proteins) of the marine bacteria differ from terrestrial bacteria.

We propose to purchase an electrospray HPLC mass spectrometer (single quadrupole) to carry out four diverse structure-function studies, to provide training in an emerging analytical method for graduate students and post doctoral fellows, and to provide other researchers within the Chemistry Department and UCSB campus access to a contemporary molecular mass determination method, a technique presently unavailable on the campus. The first major project focuses on both bacterial and mammalian DNA methyltransferases. The target bacterial enzyme is the EcoRI DNA methyltransferase. Ongoing work on this NSF supported project has used various LC-MS methods, and the proposed work extends this effort. Characterization of critical histidines within the enzyme is proposed; a novel electrospray LC-MS method is under development and application to the methyltransferase should identify the essential histidine(s). The proposed LC-MS method is a significant improvement over presently used spectrophotometric methods and may be generally applicable. An LC-MS based strategy is proposed to determine which elements of the mammalian cytosine DNA methyltransferase are in contact with its substrate. A related strategy is proposed to identify portions of the DNA substrate contacted by the enzyme. The extent and site of post- translational modification of the mammalian enzyme are also proposed to be investigated by LC-MS methods. The characterization of the mammalian enzyme is important for understanding what role this protein plays in gene regulation, cancer, and genetic imprinting. The second major project focuses on the acetylcholine transporter of synaptic vesicles. Identification of the acetylcholine binding site within the protein is proposed using radiolabeled photoaffinity analogs and LC-MS methods. Characterization of various site directed mutants of the transporter is proposed, including the extent to which these mutants are modified in their post-trans lational modification. A related proposed set of experiments is designed to assess how different growth conditions impact on the post-translational processing of the transporter. The proposed structure-function analysis of the transporter should help elucidate how the neurotransmitter acetylcholine functions. The third project proposes to use LC-MS methods to elucidate metal ion binding selectivities of siderophores produced by open ocean marine bacteria. The metal binding affinity and selectivity of the recently identified siderophore Alterobactin A, the first structurally characterized siderophore from an open ocean organism, will be determined. Thus the speciation of the siderophore in seawater can be determined. A novel LC-MS method is proposed to screen a large number of potential metals; application to other marine siderophores is proposed. The fourth project focuses on the use of high field N.M.R. to investigate protein- nucleic acid and protein-protein interactions. LC-MS is proposed as an additional means of characterizing the target biomolecules. The purchase of the proposed LC-MS instrument would enable the training of numerous graduate students and research fellows involved in these projects, as well as undergraduates and other individuals associated with intended minor users. This proposed training targets the increasing need in the biotechnology industry for protein chemists trained in contemporary analytical methods.

This award in the Inorganic, Bioinorganic, and Organometallic Chemistry program supports research by Dr. Alison Butler of the Chemistry Department, University of California at Santa Barbara, on marine haloperoxidase enzymes. The reactivities of vanadium bromoperoxidase and FeHeme bromoperoxidase, including their roles in biosynthesis, will be investigated using functional model complexes and enzyme studies. Vanadium complexes of alpha-helical peptides and alpha-helical peptide bundles that closely resemble vanadium haloperoxidases will be synthesized and tested. In addition some new mesoporous and titanium dioxide materials will be prepared and tested for peroxidative halogenation reactivity. Reactivity comparisons will be made to marine haloperoxides isolated from chiral halogenated acetogenins and sesquiterpenes produced from marine algae. The halide selectivity of vanadium haloperoxidases from algae that evolve chlorinated and brominated hydrocarbons will be investigated. Many marine natural products and enzymes have important industrial applications in the specialty chemical, diagnostics, pharmaceutical, and biotechnology industries. Development of the use of some of these natural products has been inhibited by lack of availability of sufficient quantities. This work will identify functional mimics for some marine haloperoxidases present in marine algae. These compounds have potential use as catalysts for production of oxidants and halogenating agents in situ, processes that would be environmentally beneficial alternatives to present technology.

Biochemistry occupies a unique position at the interface between the physical and biological sciences, generating a need for educational programs which focus on quantitative as well as descriptive aspects of the field. However, most curricula provide limited exposure to chemical and biophysical approaches. We are addressing this deficiency at UCSB via a new major in Biochemistry within the auspices of the Chemistry Department. Central to the curriculum are two new laboratories with emphasis on quantitative and analytical aspects of biological phenomena. This proposal seeks funding to equip these two laboratories. Instrumentation requested includes UV-visible atomic absorption and circular dichroism spectrometers. The new laboratories will enhance undergraduate laboratory experiences via a research-oriented teaching perspective in which students are given experimental objectives but only general protocols. Guidance is provided as the students turn the objectives into detailed protocols. Students will be asked to integrate diverse approaches while focusing on the same enzyme for an extended period. This approach better resembles the working mode of practicing scientists than does the usual class experience of unrelated experiments. We expect that these laboratories will permit students to develop highly marketable skills in protein chemistry, enzymology and biophysics. It is also hoped that students will more directly experience the excitement of scientific research as they learn to think creatively and quantitatively. Such an experience should be lasting and will help educate professionals in areas such as business, law and primary education, to better grasp the impact of the biotechnology revolution on society. The experiments will be disseminated through presentations and a published laboratory manual.

Mass spectrometry has recently become one of the most powerful techniques for structural characterization of biological molecules, including peptides, proteins and nucleic acids. Tandem mass spectrometry is particularly useful for sequencing these molecules, especially when only small amounts of material are available. The quadrupole time-of-flight tandem mass spectrometer will be used for routine fragmentation and unequivocal daughter fragment identification and characterization. Specific projects which will use this instrumentation include 1) investigations of the molecular mechanisms of iron acquisition by marine microorganisms in order to understand the role of iron in regulating the global carbon cycle and climate change; 2) the search for biological molecular markers of autism, 3) the synthesis and characterization of polymeric peptide adhesives with industrial and medical applications, 4) the development biological nanofabrication processes of new high performance composites and 5) investigations of amphiphilic peptides to control the cell response, particularly on biologically active material surfaces.

The quadrupole time-of flight mass spectrometer will include a high pressure liquid chromatograph to separate compounds before analyzing their masses and fragmentation patterns. The mass spectrometer will consist of a quadrupole as the first mass analyzer, followed by a quadrupole collision cell and a time-of-flight detector as the second mass analyzer. The system will also be configured with nanospray and micro ion spray capabilities to allow for a range of flow rates and to permit the small amounts of biological samples to be analyzed. The system will use electrospray ionization (ESI) for soft ionization of proteins and peptides or atmospheric pressure chemical ionization (APCI) for analysis of polar organic molecules.

The quadrupole time-of flight mass spectrometer will significantly enhancing the research infrastructure at the University of California, Santa Barbara by extending the mass range and sensitivity capabilities of the UCSB Mass Spectrometry Facility which is housed in the Department of Chemistry and Biochemistry. For example, this instrument provides the capability to elucidate the structures of peptides, proteins and nucleic acids, which is required by the research groups that will use this instrumentation. This mass spectrometer will also significantly enhance student training, by providing exposure to and training in modern structure determination methodologies, which will certainly be useful in the emerging areas of proteomics, genomics and bioinformatics.

Abstract
CTS-0103516
M.Tirrell, University of California-Santa Barbara


The work proposed here aims to develop the science of spontaneously dividing three-dimensional space into compartments, that is, into controlled environments, at the nanometer size scale, in order to accomplish several engineering objectives. The objectives include: controlled release of therapeutic agents (e.g., drugs, genetic materials); controlled access to biofunctional components (switching or masking activities when desirable); embedding biological signaling within 3D matrices (nano-phase-separated block co-polypeptides decorated with targeting or "homing" ligands) and using surface patterning and templating to produce novel or tailored structures and environments. Four project areas encompass and organize our overall plan: 1. Creating nano-environments via lipid encapsulation; 2. Nano-environments from peptide amphiphiles; 3. Amphiphilic block copolypeptides with hierarchical structures; 4. Patterned surfaces for self-assembly. The work we will do is conceptually similar to creating artificial cells in the sense of separating regions for different functions (without any attempt to build in self-replication). We are aiming toward bio-mimetic structures for functions that may not be naturally occurring, and that mimic or supply interesting functionality. The kinds of functions we wish to incorporate vary from biological (e.g., cell adhesion) to non-biological (e.g., fluid connectivity).

The science we will pursue is the principle of spontaneously creating compartments or confined regions with a definite inside and outside. As a practical matter, this means delving deeper into controlled formation of micelles, vesicles, domains, tubules and other controlled regions, as part of larger assemblies of nanoscale components. We will synthesize new lipid-like and macromolecular architectures to drive self-assembly in ways that can encapsulate some species and exclude or display others, controllably, on the interiors and exteriors, respectively, of defined regions. Our research will produce new materials for biomedical applications, new therapeutic approaches based on controllable binding and transport processes and new ways of integrating biological structures with semiconductor fabricated devices. Our core expertise includes extensive experience with lipid and macromolecular structure and phase behavior, based on substantial ability to synthesize new molecules. We have experience with assessing and influencing biological activities and functions, ranging from cell adhesion, to drug delivery and gene transfection, to the roles of metal ions in growth processes and pathological conditions. Characterization expertise and facilities for all of this work are readily available among the members of this collaboration: electron microscopy (adapted in several ways for soft, wet, biological samples), scanning probe nicroscopies, optical microscopy (with fluorescence, confocal, interference and video capabilities), surface force measurements, x-ray and neutron scattering, neutron reflectometry and organic synthesis.

The interdisciplinary talents of this team are essential to educate students broadly in the new fields of nanotechnology and biotechnology. The five graduate students and one postdoctoral fellow supported by this proposed grant will work in broad areas of the overall project where interests of several groups overlap strongly. In this way, the students will have continued exposure to the full interdisciplinary group of biochemists, chemists, physicists, chemical engineers and materials scientists that make up our team. An active effort is planned to attract a diverse population of students to this project. We believe that the students and fellow trained in the course of this research will be extraordinarily flexible in their talents, and therefore exceptionally, well-prepared for careers in industry or universities, because of the multiple advisor, multiple technique environment we will provide. The PI and co-PI's will manage this project to continuously promote this interdisciplinary approach in the selection of specific projects to be pursued. The efforts from this project will feed new ideas, examples and practical experience into a new laboratory-based course under development entitled, "Biomaterials Preparation and Characterization".

DESCRIPTION (Adapted from applicant's abstract): The objectives of this research are to improve our understanding of the mechanisms of metal acquisition by microorganisms in the marine environment. Interest in the mechanisms of acquisition of iron (and other metal ions) by oceanic bacteria derives from the unique transition metal ion composition of the ocean and the discrepancy between iron availability and requirements. Iron is a limiting nutrient to marine microorganisms over much of the world's oceans at a concentration of 0.02-1 nM in surface seawater, whereas molybdenum and vanadium are the two most abundant transition metal ions at 100 nM and 20-35 nM, respectively. In the previous grant period the Principal Investigator discovered a new class of self-assembling amphiphilic peptide siderophores, the marinobactins and aquachelins, produced by two phylogenetically distinct genera within the marine gamma proteobacteria. The only siderophores which bear a structural resemblance to the marinobactins and aquachelins are the amphiphilic mycobactin and exochelin siderophores. These siderophores are produced by mycobacteria, such as Mycobacterium tuberculosis, the bacterium causing tuberculosis. Little is known about the molecular mechanism of pathogenesis of M. tuberculosis, however, its capacity to infect the host is closely linked to its ability to acquire iron. The specific aims of the proposed research include I) further characterization of the amphiphilic marine siderophores and the mycobactins, II) further investigations of the Alteromonas luteoviolacea system, the marine bacterium which produces the alterobactin siderophores and III) the isolation and structural characterization of siderophores produced by other oceanic bacteria. These studies are the first part of an investigation into whether the mechanisms of iron acquisition (e.g., siderophore-mediated sequestration of the iron, outer membrane receptor protein recognition of the metal siderophore complex, transport, and metal regulation of these processes, etc.) by marine bacteria differ from terrestrial bacteria.

This award by the Inorganic, Bioinorganic and Organometallic Chemistry program supports research by Alison Butler, University of California Santa Barbara Department of Chemistry and Biochemistry. Butler is studying haloperoxidase enzymes, more specifically the vanadium bromoperoxidases found in several types of marine algae. The mechanisms of these enzymes and the biogenesis of halogenated terpene and acetogenin marine natural products will be explored. Using site-directed mutagenesis, Butler will determine the functional role of selected amino acid residues in the enzymes and prepare mutants suitable for in vitro reactivity. These mutants may eventually be used for the industrial synthesis of halogenated compounds suitable for medical applications.

In addition to the fundamental bioinorganic chemistry and enzymology proposed, the work has broad implications for marine biology and pharmaceutical chemistry. Butler also trains a diverse group of students in an emerging interdisciplinary field

[unreadable] DESCRIPTION (provided by applicant): The objectives of this research are to improve our understanding of the mechanisms of metal acquisition by microorganisms in the marine environment. Interest in the mechanisms of acquisition of iron (and other metal ions) by oceanic bacteria derives from the unique transition metal ion composition of the ocean. Iron is a limiting nutrient to marine microorganisms over much of the world's oceans and has now been shown to regulate the global carbon cycle. Results from the last grant period demonstrated that the majority of marine siderophore structures fall within two categories: 1) suites of self-assembling amphiphilic peptide siderophores including the marinobactins, aquachelins, amphibactins, ochrobactins and synechobactins, which are produced by phylogenetically distinct genera of bacteria; and 2) siderophores containing an alpha- hydroxycarboxylic acid moiety (e.g., beta-hydroxyaspartic acid, citric acid) which when coordinated to Fe(lll) are photoreactive, including the ferric complexes of aquachelins, marinobactins, aerobactin, petrobactins, synechobactins and ochrobactins. The hypothesis to be tested is that the amphiphilic character and photoreactivity confer an advantage for microbial growth tailored to the chemical and physical constraints of the ocean. Certain siderophores produced by pathogenic bacteria bear a structural resemblance to the amphiphilic siderophores produced by marine bacteria, including the mycobactins and carboxymycobactins, produced by mycobacteria, such as M. tuberculosis, which caused tuberculosis and acinetoferrin produced by Acinetobacter haemolyticus which causes respiratory disease. Little is known, however, about the importance of the amphiphilic and photoreactive properties of the mycobacterial and acinetobacter siderophores on the disease state. The specific aims of the proposed research are to i) investigate the photoreactivity of the marine ferric siderophores with alpha-hydroxy acid groups, ii) investigate the amphiphilic properties of the suites of marine amphiphilic siderophores, iii) investigate the photoreactivity and amphiphilic effects on iron acquisition by the source bacteria, and iv) isolate and characterize new siderophores produced by selected other marine bacteria. [unreadable] [unreadable]

Technical Abstract

The development project is aimed at advancing the design technology for ultra-high-resolution small angle x-ray scattering (SAXS) instrumentation and x-ray optics with broad applications in nanoscale structure characterization. A new optical design concept that can significantly enhance (up to 10-fold) the resolution and signal-to-noise ratio in SAXS measurements will be developed. The superior performance results from a compound optical configuration incorporating both a primary monochromator mirror and a pre-sample secondary focusing mirror to increase resolution and peak intensity. This unique design is expected to supplant the prevalent three-pinhole configuration in current SAXS instruments. The scientific and engineering problems of interest cover a range of multidisciplinary fields including soft condensed matter, biological physics and bioengineering, neuroscience, and bioinorganic chemistry. The instrument will operate out of the x-ray facility of the Materials Research Laboratory, with an established user base of more than 250 researchers from campus, other institutions and local industry. The development should broadly impact the national academic research infrastructure by advancing the optical design and performance of SAXS instrumentation used in diverse research areas in nanoscience and nanotechnology. The investigators of this project will continue their involvement in their numerous outreach programs available at UCSB to improve access to science for diverse groups, including undergraduate and graduate student training, outreach to K-12 students and teachers, and community outreach.

Lay Abstract

Enhancing structure characterization of nanomaterials is critical to the emerging areas of nanoscience, nanotechnology, and biotechnology. We will develop a laboratory-based microbeam x-ray scattering instrument for discovering the structures of novel new materials on the 1 nanometer to 1000 nanometer scale. The performance of this new instrument will exceed the best commercially available x-ray instrument and will provide a significant enhancement to the campus infrastructure in nanoscience and technology. The development of this cutting edge x-ray characterization tool will establish UCSB as one of strongest institutions in the x-ray characterization area, which will attract users not only from multiple campus groups but also from other research institutions as well. The project provides an excellent training opportunity to graduate students and postdoctoral researchers who will not only participate in building the cutting-edge x-ray tool but also be able to utilize it in a series of research projects which will take advantage of the new capability afforded by the instrument. The x-ray development program will be integrated with the ongoing outreach activities of the principle investigators in mentoring undergraduate students and local high school teachers participating in the large number of ongoing summer internship programs at UCSB.

The objectives of this research are to improve our understanding of the mechanisms of metal acquisition by microorganisms in the marine environment. Interest in the mechanisms of acquisition of iron (and other metal ions) by oceanic bacteria derives from the unique transition metal ion composition of the ocean. Iron is a limiting nutrient to marine microorganisms over much of the world's oceans and has now been shown to regulate the global carbon cycle. Results from the last grant period demonstrated that the majority of marine siderophore structures fall within two categories: 1) suites of self-assembling amphiphilic peptide siderophores including the marinobactins, aquachelins, amphibactins, ochrobactins and synechobactins, which are produced by phylogenetically distinct genera of bacteria;and 2) siderophores containing an alpha- hydroxycarboxylic acid moiety (e.g., beta-hydroxyaspartic acid, citric acid) which when coordinated to Fe(lll) are photoreactive, including the ferric complexes of aquachelins, marinobactins, aerobactin, petrobactins, synechobactins and ochrobactins. The hypothesis to be tested is that the amphiphilic character and photoreactivity confer an advantage for microbial growth tailored to the chemical and physical constraints of the ocean. Certain siderophores produced by pathogenic bacteria bear a structural resemblance to the amphiphilic siderophores produced by marine bacteria, including the mycobactins and carboxymycobactins, produced by mycobacteria, such as M. tuberculosis, which caused tuberculosis and acinetoferrin produced by Acinetobacter haemolyticus which causes respiratory disease. Little is known, however, about the importance of the amphiphilic and photoreactive properties of the mycobacterial and acinetobacter siderophores on the disease state. The specific aims of the proposed research are to i) investigate the photoreactivity of the marine ferric siderophores with alpha-hydroxy acid groups, ii) investigate the amphiphilic properties of the suites of marine amphiphilic siderophores, iii)investigate the photoreactivity and amphiphilic effects on iron acquisition by the source bacteria, and iv) isolate and characterize new siderophores produced by selected other marine bacteria.

This award in the Inorganic, Bioinorganic and Organometallic Chemistry program supports work by Professor Alison Butler at the University of California at Santa Barbara to probe reactions catalyzed by vanadium bromoperoxidases (V-BrPO) from species of marine red algae in the biosynthesis of brominated spiro--bicyclic sesquiterpene natural products, brominated fused-ring diterpene natural products, brominated acyclic monoterpene natural products, and bromofuranone natural products. The mechanism of action of these enzymes will be further investigated through bromine isotope fractionation studies.

Many marine natural products and enzymes have important industrial applications in the specialty chemical, diagnostics, pharmaceutical and biotechnology industries. Mechanistic enzyme studies of V-BrPO can be used to form the basis of an economical, alternative and environmentally sound source of brominated marine natural products, as well as further elucidating the mechanism of halogenation. Elucidation of pathways for the biosynthesis of new compounds of biomedical and industrial importance is an anticipated impact. This project supports the education and training of graduate students, undergraduate students and postdoctoral fellows in a highly interdisciplinary research project in a manner that will serve to broaden and deepen the level of research training. The graduate students and PI participate in an extensive UCSB campus network providing undergraduate research training and K-12 outreach, across diverse populations.

This award in the Chemistry of Life Processes (CLP) program supports work by Professor Alison Butler at the University of California, Santa Barbara to carry out fundamental studies on the process of iron acquisition by bacteria that is mediated by siderophores. Nearly all bacteria require iron to grow. Siderophores are low molecular mass chelating ligands produced by bacteria that coordinate Fe(III) with very high affinity and facilitate iron uptake by the bacterium. Marine bacteria often produce suites of amphiphilic siderophores that vary in the nature of the fatty acid tail. The interactions of the amphiphilic siderophores, their self-assembled structures and the bacteria will be probed to investigate whether the amphiphilic character of these siderophores confers a distinct molecular advantage for microbial iron acquisition.

This project supports the education and training of graduate and undergraduate students in a highly interdisciplinary research project in a manner that will serve to broaden and deepen the level of research training. Some marine bacteria grow on petroleum hydrocarbons as their sole source of carbon and energy; yet before bacteria can begin to oxidize hydrocarbons, they must first acquire iron for growth and then for assimilation into the key enzymes. Thus understanding how oil-degrading bacteria acquire the essential nutrient, iron, would benefit efforts to enhance microbial hydrocarbon oxidation of environmental concern.

Nearly all bacteria require iron to grow. Understanding the process by which bacteria obtain iron from their surroundings provides valuable insight into how to disrupt the iron uptake process, and suggests potential new strategies to limit growth of deleterious microbes. The focus of this proposal is to find out how unique compounds called siderophores are produced for iron uptake in Vibrio harveyi and other microbes for which their production is tied to bacterial colony formation and survival. Siderophores are natural materials produced by bacteria that bind iron(III) very tightly playing a vital role in iron uptake by the bacterium. Through these investigations, graduate students will be trained in the application of a broad spectrum of modern techniques to a multidisciplinary research program. The graduate students will, in turn, also gain valuable experience as mentors to undergraduate researchers in the laboratory, and undergraduates will gain hands-on research experience.

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Alison Butler from the University of California, Santa Barbara to investigate the biosynthesis of key amphiphilic siderophores, such as the amphi-enterobactins, to investigate their physical properties including the ferric stability constants and membrane partitioning constants for different forms of the amphi-enterobactins, to investigate key esterases and outer membrane receptor proteins present in the genome of V. harveyi which are suspected to be important in the mechanism of iron uptake, as well as to investigate other key amphiphilic siderophores. V. harveyi is the widely studied model organism for quorum sensing, the process by which bacteria sense cell density. Discoveries from these investigations will provide new insights into the importance of the fatty acid in acylated siderophores in the iron uptake process.

With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Professor Alison Butler from the University of California, Santa Barbara to investigate the properties of compounds called catechol-siderophores that are produced by bacteria. The compounds are similar to the molecules that make it possible for mussels to cling tenaciously to rocks in the ocean. This research examines the reasons for the recently discovered properties that allow mussels to cling even to slick, wet surfaces. This project may provide an understanding of the biological phenomenon and may lead to the design of compounds that can adhere even under water. The role of catechol-siderophores in iron acquisition by bacteria is also investigated. This research project provides broad multidisciplinary training for graduate and undergraduate students. Professor Butler and her students are involved in outreach workshops including, CAMP (California Alliance for Minority Participation), an NSF-funded program supporting minority undergraduate students in science, technology, engineering and mathematics fields, and SCOPE (Science as a Career Outreach Project Experiment), a program for graduate students to talk in local high schools about undergraduate and graduate education and the value of the sciences as a career choice.

The research is investigates siderophores and analogs containing both catechol and amine functional groups that mimic the strong wet adhesive properties of mussel foot proteins. The overall goals of the first part of this proposal are to elucidate the synergistic role of the catechol and the amine functionalities in displacing the interfacial hydration layer that develops on mineral surfaces leading to robust adhesion. The approach is to design and investigate the surface adhesive properties of new biomimetic compounds through direct force measurements with a surface forces apparatus. The goals of the second part of this research are to investigate the biosynthesis, uptake, and iron(III) release mechanisms of acylated tetra L-serine, and tris-catechol siderophores through investigation of key fatty acid coenzyme A ligases, outer membrane receptor proteins, and esterases identified in the genomes of the producing bacteria.

With the support of the Chemistry of Life Processes Program in the Chemistry Division, Dr. Alison Butler from the University of California-Santa Barbara will investigate compounds called siderophores that bacteria produce to obtain iron, an essential nutrient for the growth of most bacteria. Siderophores, which is Greek for iron (sideros)-liking (phore), bind iron with very high affinity and transport it into the cells of bacteria, which is a process essential for the life of the bacteria. Dr. Butler and her team will focus on the study of the effect of chirality, i.e. their left handed or right handed shape, on the iron uptake by the bacteria. The new knowledge gained from this study may be beneficial to the control of deleterious microbial infections if the chirality could be used to disrupt the process of iron uptake by microbes. The graduate and undergraduate students involved in the research will acquire a broad education and training in bioinorganic and bioorganic chemistry as well as a foundation in interdisciplinary research, likely to be useful in their future careers. The PI and her students will also engage in outreach workshops through UCSB’s Center for Science and Engineering Partnerships (CSEP) and the Summer Institute in Science and Math (SIMS) to assist undergraduates in developing effective scientific communication skills and to assist mentors in developing effective mentoring strategies.

The research supported by this award focuses on a new combinatoric suite of tris-catechol siderophores, tris-(2,3-DHB--L/D-CAA--L-Ser), in which DHB if dihydroxybenzoate and CAA is the cationic amino acid L/D-Lys, L/D-Arg or L/D-Orn. The diastereomeric pairs of each siderophore form complexes with Fe(III), which are enantiomeric. The specific aims of the research are (i) to elucidate the structural and molecular characteristics that govern the chirality of the Fe(III)-enantiomeric complexes, (ii) to investigate the exchange of Fe(III) between diastereomeric siderophores, including the effect of the nature of the CAA on the exchange process; and 3) to investigate the influence of the stereochemistry of Fe(III)-[tris(2,3-DHB--L/D-CAA--L-Ser)] on microbial growth. The new siderophores will be isolated, relevant synthetic analogues will be synthesized and both will be structurally characterized. Circular dichroism, racemic crystallization, and molecular modeling will be carried out on the Fe(III)-siderophore complexes and appropriate synthetic analogues. The kinetics of Fe(III) exchange will be followed by circular dichroism. Microbial growth will be monitored in disk-diffusion bioassays.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.