Pyochelin
Related genes: fptA;
pchA;
pchB;
pchC;
pchD;
pchE;
pchF;
pchG;
pchH;
pchI;
pchR;
Keywords: Iron uptake;
Siderophore;
Characteristics:
 The genes for pyochelin biosynthesis are in two separate operons, pchDCBA, involved in the synthesis of the pyochelin precursor salicylic acid and pchEFGHI. pchHI appear to have an export function. The fptA gene encoding the 75 kDa ferric pyochelin receptor occurs immediately downstream of pchI
Functions:
Effective at promoting iron uptake in P. aeruginosa
Catalyzes the formation of tissue-damaging free radicals
Pyochelin also binds other transition metals (e.g. Mo(IV), Co(II)) with appreciable affinity and is implicated in the delivery of both Co(II) and Mo(IV) to P. aeruginosa cells
Mechanism:
Pyochelin is a structurally unique siderophore possessing phenolate, but neither a hydroxamate nor a catecholate moiety. Pyochelin binds Fe (III) in a 2:1 stoichiometry with comparatively low affinity (stability constant, 10**5)
FptA is the specific receptor for Fe(III)-pyochelin
References:
 Ankenbauer RG, Quan HN, 1994. FptA, the Fe(III)-pyochelin receptor of Pseudomonas aeruginosa: a phenolate siderophore receptor homologous to hydroxamate siderophore receptors. J. Bacteriol. 176(2):307-319.
DeWitte JJ, et al., 2001. Assessment of structural features of the Pseudomonas siderophore pyochelin required for its ability to promote oxidant-mediated endothelial cell injury. Arch Biochem. Biophys. 393(2):236-244.
Crosa JH, Walsh CT, 2002. Genetics and assembly line enzymology of siderophore biosynthesis in bacteria. Microbiol. Mol. Biol. Rev. 66(2):223-249.
Poole K, McKay GA, 2003. Iron acquisition and its control in Pseudomonas aeruginosa: many roads lead to Rome. Front. Biosci. 8:661-686.
Pyoverdine
Related genes: fpvA;
pvdA;
pvdD;
pvdE;
pvdS;
Keywords: Iron uptake;
Siderophore;
Pigment;
Characteristics:
A greenish-yellow compound, a hydroxyquinolone chromophore to which an amino acid tail is attached, the tail can vary in length
The synthesis of pyoverdine requires a special σ factor, PvdS, which is in turn regulated by the Fur repressor
Also called pseudobactin
Functions:
Effective at acquiring iron from transferrin and lactoferrin
Cytotoxic due to its ability to stimulating the production of reactive oxygen species
Mechanism:
Pvd is a fluorescent dihydroxyquinoline derivative connected to a small peptide and contains hydroxamate and catecholate residues to chelate ferric ion, Fe (III). Pvd chelates Fe (III) in a 1:1 stoichiometry with high affinity (stability constant, 10**32)
FpvA is the specific receptor for Fe(III)-pyoverdin
References:
Meyer JM, et al., 1996. Pyoverdin is essential for virulence of Pseudomonas aeruginosa. Infect. Immun. 64(2):518-523.
Xiao R, Kisaalita WS, 1997. Iron acquisition from transferrin and lactoferrin by Pseudomonas aeruginosa pyoverdin. Microbiology. 143:2509-2515.
Shen J, et al., 2002. FpvA receptor involvement in pyoverdine biosynthesis in Pseudomonas aeruginosa. J. Bacteriol. 184(12):3268-3275.
Poole K, McKay GA, 2003. Iron acquisition and its control in Pseudomonas aeruginosa: many roads lead to Rome. Front. Biosci. 8:661-686.
Ravel J, Cornelis P, 2003. Genomics of pyoverdine-mediated iron uptake in pseudomonads. Trends Microbiol. 11(5):195-200.
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Bacteria
