P>Pyoverdine biosynthesis in fluorescent Pseudomonas spp. and especially in the opportunistic human pathogen Pseudomonas aeruginosa has been extensively studied. The acylase PvdQ is required for a maturation step in pyoverdine biosynthesis but also has been proven to be effective in degrading long-chain N-acyl homoserine lactones (AHLs). These molecules are used as quorum-sensing molecules by Gram-negative bacteria such as Pseudomonads themselves. Interestingly, the pvdQ gene is part of a pyoverdine cluster in P. aeruginosa and P. syringae but not in other fluorescent Pseudomonas spp. In this study we have compared the activities of PvdQ orthologues from various species and provide evidence for conserved functions in Pseudomonas fluorescens PfO-1, P. putida KT2440 and P. aeruginosa PA14. Despite large differences in genomic organization, expression of each of these pvdQ orthologues is regulated by iron availability. Moreover, PvdQ and its orthologues have conserved substrate specificity for AHLs and play a role in pyoverdine production in all tested Pseudomonas species. These data strongly suggest that the role of PvdQ in pyoverdine biosynthesis is conserved among Pseudomonas spp., while the control that PvdQ exerts in P. aeruginosa over its own quorum-sensing signals seems to be unique to this bacterium.
