Dihydroaeruginoic acid synthetase and pyochelin synthetase, products of the pchEF genes, are induced by extracellular pyochelin in Pseudomonas aeruginosa.
The siderophore pyochelin of Pseudomonas aeruginosa is derived from one molecule of salicylate and two molecules of cysteine. Two cotranscribed genes, pchEF, encoding peptide synthetases have been identified and characterized. pchE was required for the conversion of salicylate to dihydroaeruginoate (Dha), the condensation product of salicylate and one cysteine residue and pchF was essential for the synthesis of pyochelin from Dha. The deduced PchE (156 kDa) and PchF (197 kDa) proteins had adenylation, thiolation and condensation/cyclization motifs arranged as modules which are typical of those peptide synthetases forming thiazoline rings. The pchEF genes were coregulated with the pchDCBA operon, which provides enzymes for the synthesis (PchBA) and activation (PchD) of salicylate as well as a putative thioesterase (PchC). Expression of a translational pchE'-'lacZ fusion was strictly dependent on the PchR regulator and was induced by extracellular pyochelin, the end product of the pathway. Iron replete conditions led to Fur (ferric uptake regulator)-dependent repression of the pchE'-'lacZ fusion. A translational pchD'-'lacZ fusion was also positively regulated by PchR and pyochelin and repressed by Fur and iron. Thus, autoinduction by pyochelin (or ferric pyochelin) and repression by iron ensure a sensitive control of the pyochelin pathway in P. aeruginosa.
Reimmann
Cornelia
C
Laboratoire de Biologie Microbienne, Universite Lausanne, CH-1015 Lausanne, Switzerland de.
Serino
Laura
L
Laboratoire de Biologie Microbienne, Universite Lausanne, CH-1015 Lausanne, Switzerland de.
Beyeler
Markus
M
Laboratoire de Biologie Microbienne, Universite Lausanne, CH-1015 Lausanne, Switzerland de.
Haa
Dieter
D
Laboratoire de Biologie Microbienne, Universite Lausanne, CH-1015 Lausanne, Switzerland de.
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins; D001483:Base Sequence; D004790:Enzyme Induction; D005798:Genes, Bacterial; D007501:Iron / Q000378:metabolism; D008969:Molecular Sequence Data; D009876:Operon / Q000235:genetics; D010453:Peptide Synthases / Q000096:biosynthesis* / Q000235:genetics; D010636:Phenols / Q000378:metabolism* / Q000494:pharmacology; D020161:Physical Chromosome Mapping; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics; D011956:Receptors, Cell Surface / Q000235:genetics; D012097:Repressor Proteins; D012459:Salicylates / Q000378:metabolism; D013844:Thiazoles / Q000378:metabolism*; D014158:Transcription, Genetic; D001616:beta-Galactosidase / Q000378:metabolism
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; C075523:FPTA protein, Pseudomonas; D010636:Phenols; D011956:Receptors, Cell Surface; D012097:Repressor Proteins; D012459:Salicylates; D013844:Thiazoles; C068477:ferric uptake regulating proteins, bacterial; C055755:2'-(2-hydroxyphenyl)-2'-thiazoline-4'-carboxylic acid; C025316:pyochelin; D007501:Iron; D001616:beta-Galactosidase; D010453:Peptide Synthases