The goal is this research is to understand how Pseudomonas aeruginosa obtains extracellular iron to support growth during human infections. Our long-term goal is to use this understanding toward the construction of growth-inhibiting or bactericidal compounds. To be a successful pathogen, P. aeruginosa must mobilize iron from unavailable mammalian iron reserves, serum transferrin and secretory lactoferrin into forms which are available to bacterial metabolism. This bacterium depends upon three extracellular products to mobilize unavailable iron. Pyocyanin is a reducing agent which can catalyze the removal of Fe(II) from transferrin. Pyochelin and pyoverdin (siderophores) are iron binding compounds which supply iron in utilizable forms to high affinity transport systems. Pyoverdin appears to be the most effective siderophore. The first specific aim of this proposal will be to follow the fates of both iron and pyoverdin during transport using radiolabelling studies and to compare these transport mechanisms with those used for ferripyochelin. The concerted activities of all three extracellular products will be investigated during transport assays. High pressure liquid chromatography (HPLC) and electrophoresis will be used in conjunction with transport assays to determine the participation of the bacterial surface and of proteolytic enzymes in iron mobilization from transferrin. The biosynthesis of pyoverdin will be investigated by both amino acid analysis of pigments isolated by isoelectric focusing and HPLC, and by labelling the forms of pyoverdin with radioactive amino acids. Mutants which produce abbreviated segments of the peptide portion of the siderophore will be fed radiolabelled amino acids and their products will be analyzed to yield a sequential perspective of peptide formation. Completion of pigment synthesis will be studied by following the incorporation of (14C)shikimate into the quinoline derivatives and finally into the dihydroxyquinoline of pyoverdin. NMR and mass spectroscopy will be employed to analyze possible alteration in the dihydroxyquinoline moiety of pyoverdin. This information and these compounds will be used in our research for analogues of siderophores and precursors which inhibit bacterial iron acquisition.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI013120-12
Application #
3125384
Study Section
Bacteriology and Mycology Subcommittee 1 (BM)
Project Start
1977-01-01
Project End
1990-09-30
Budget Start
1989-04-01
Budget End
1990-09-30
Support Year
12
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Medicine
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Ankenbauer, R G (1992) Cloning of the outer membrane high-affinity Fe(III)-pyochelin receptor of Pseudomonas aeruginosa. J Bacteriol 174:4401-9
Ankenbauer, R G; Staley, A L; Rinehart, K L et al. (1991) Mutasynthesis of siderophore analogues by Pseudomonas aeruginosa. Proc Natl Acad Sci U S A 88:1878-82
Coffman, T J; Cox, C D; Edeker, B L et al. (1990) Possible role of bacterial siderophores in inflammation. Iron bound to the Pseudomonas siderophore pyochelin can function as a hydroxyl radical catalyst. J Clin Invest 86:1030-7
Ankenbauer, R G; Toyokuni, T; Staley, A et al. (1988) Synthesis and biological activity of pyochelin, a siderophore of Pseudomonas aeruginosa. J Bacteriol 170:5344-51
Ankenbauer, R G; Cox, C D (1988) Isolation and characterization of Pseudomonas aeruginosa mutants requiring salicylic acid for pyochelin biosynthesis. J Bacteriol 170:5364-7
Cox, C D (1986) Role of pyocyanin in the acquisition of iron from transferrin. Infect Immun 52:263-70
Ankenbauer, R; Hanne, L F; Cox, C D (1986) Mapping of mutations in Pseudomonas aeruginosa defective in pyoverdin production. J Bacteriol 167:7-11
Sriyosachati, S; Cox, C D (1986) Siderophore-mediated iron acquisition from transferrin by Pseudomonas aeruginosa. Infect Immun 52:885-91
Cox, C D (1985) Iron transport and serum resistance in Pseudomonas aeruginosa. Antibiot Chemother 36:1-12
Ankenbauer, R; Sriyosachati, S; Cox, C D (1985) Effects of siderophores on the growth of Pseudomonas aeruginosa in human serum and transferrin. Infect Immun 49:132-40

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