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.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
Research Project (R01)
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Metallobiochemistry Study Section (BMT)
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Preusch, Peter C
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University of California Santa Barbara
Schools of Arts and Sciences
Santa Barbara
United States
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Gauglitz, Julia M; Iinishi, Akira; Ito, Yusai et al. (2014) Microbial tailoring of acyl peptidic siderophores. Biochemistry 53:2624-31
Gauglitz, Julia M; Butler, Alison (2013) Amino acid variability in the peptide composition of a suite of amphiphilic peptide siderophores from an open ocean Vibrio species. J Biol Inorg Chem 18:489-97
Gauglitz, Julia M; Zhou, Hongjun; Butler, Alison (2012) A suite of citrate-derived siderophores from a marine Vibrio species isolated following the Deepwater Horizon oil spill. J Inorg Biochem 107:90-5
Vraspir, Julia M; Holt, Pamela D; Butler, Alison (2011) Identification of new members within suites of amphiphilic marine siderophores. Biometals 24:85-92
Sandy, Moriah; Butler, Alison (2011) Chrysobactin siderophores produced by Dickeya chrysanthemi EC16. J Nat Prod 74:1207-12
Owen, Tate; Butler, Alison (2011) Metallosurfactants of bioinorganic interest: Coordination-induced self assembly. Coord Chem Rev 225:678-687
Sandy, Moriah; Han, Andrew; Blunt, John et al. (2010) Vanchrobactin and anguibactin siderophores produced by Vibrio sp. DS40M4. J Nat Prod 73:1038-43
Butler, Alison; Theisen, Roslyn M (2010) Iron(III)-siderophore coordination chemistry: Reactivity of marine siderophores. Coord Chem Rev 254:288-296
Homann, Vanessa V; Edwards, Katrina J; Webb, Eric A et al. (2009) Siderophores of Marinobacter aquaeolei: petrobactin and its sulfonated derivatives. Biometals 22:565-71
Homann, Vanessa V; Sandy, Moriah; Tincu, J Andy et al. (2009) Loihichelins A-F, a suite of amphiphilic siderophores produced by the marine bacterium Halomonas LOB-5. J Nat Prod 72:884-8

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