Yersiniabactin production requires the thioesterase domain of HMWP2 and YbtD, a putative phosphopantetheinylate transferase.
One requirement for the pathogenesis of Yersinia pestis, the causative agent of bubonic plague, is the yersiniabactin (Ybt) siderophore-dependent iron transport system that is encoded within a high-pathogenicity island (HPI) within the pgm locus of the Y. pestis chromosome. Nine gene products within the HPI have demonstrated functions in the nonribosomal peptide synthesis (NRPS)/polyketide (PK) synthesis or transport of Ybt. NRPS/PK synthetase or synthase enzymes are generally activated by phosphopantetheinylation. However, no products with similarities to known phosphopantetheinyl (P-pant) transferases were found within the pgm locus. We have identified a gene, ybtD, encoded outside the HPI and pgm locus, that is necessary for function of the Ybt system and has similarities to other P-pant transferases such as EntD of Escherichia coli. A deletion within ybtD yielded a strain (KIM6-2085+) defective in siderophore production. This strain was unable to grow on iron-deficient media at 37 degrees C but could be cross-fed by culture supernatants from Ybt-producing strains of Y. pestis. The promoter region of ybtD was fused to lacZ; beta-galactosidase expression from this reporter was not regulated by the iron status of the bacterial cells or by YbtA, a positive regulator of other genes of the ybt system. The ybtD mutant failed to express indicator Ybt proteins (high-molecular-weight protein 1 [HMWP1], HMWP2, and Psn), a pattern similar to those seen with several other ybt biosynthetic mutants. In contrast, cells containing a single amino acid substitution (S2908A) in the terminal thioesterase domain of HMWP2 failed to exhibit any ybt regulatory defects but did not elaborate extracellular Ybt under iron-deficient conditions.
Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky, Lexington 40536-0084, USA.
Alexander G
AG
Bobrov
Valerie A
VA
Geoffroy
Robert D
RD
Perry
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D004269:DNA, Bacterial; D015870:Gene Expression; D033862:Iron-Binding Proteins; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009876:Operon; D033902:Periplasmic Binding Proteins; D010636:Phenols; D016601:RNA-Binding Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D017262:Siderophores / Q000096:biosynthesis*; D013844:Thiazoles; D014158:Transcription, Genetic; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics / Q000378:metabolism*; D015010:Yersinia pestis / Q000201:enzymology* / Q000235:genetics
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; D033862:Iron-Binding Proteins; D035925:Iron-Regulatory Proteins; D007506:Iron-Sulfur Proteins; D033902:Periplasmic Binding Proteins; D010636:Phenols; D016601:RNA-Binding Proteins; D017262:Siderophores; D013844:Thiazoles; C104398:yersiniabactin; D017855:Transferases (Other Substituted Phosphate Groups); C464641:YbtD protein, Yersinia pestis