Genomics of the 35-kb pvd locus and analysis of novel pvdIJK genes implicated in pyoverdine biosynthesis in Pseudomonas aeruginosa

Novel putative pyoverdine synthetase pvdIJK genes were found upstream of pv dD in the 6.2-Mb chromosome of Pseudomonas aeruginosa strain PAO1. These ge nes formed a locus implicated in pyoverdine biosynthesis. Sequence analysis showed that the product of these genes shared 43%, 60% and 57% identity wi th PvdD. PvdIJK are thought to be implicated in synthesis of pyoverdine, a siderophore chelating Fe3+. A pvdI mutant was obtained by gene disruption m utagenesis and confirmed by Southern hybridization. The pvdI mutant produce d gave no significant growth on solid media supplemented with the iron chel ator 2,2-dipyridyl; while the PvdI(-) phenotype abolished pyoverdine fluore scence. The role of PvdI in pathogenicity was tested by measuring the in vi vo growth of P. aeruginosa wild-type and mutant strains in a chronic lung i nfection rat model, and by measuring the competitive infectivity index into a neutropenic mice model. The data obtained confirmed the importance of Pv dI in virulence and iron uptake. (C) 2000 Published by Elsevier Science B.V . on behalf of the Federation of European Microbiological Societies.