The Vfm quorum sensing (QS) system is preponderant for the virulence of different species of the bacterial genus
Dickeya. The
vfm gene cluster encodes 26 genes involved in the production, sensing or transduction of the QS signal. To date, the Vfm QS signal has escaped detection by analytical chemistry methods. However, we report here a strain-specific polymorphism in the biosynthesis genes
vfmO and
vfmP, which is predicted to be related to the production of different analogues of the QS signal. Consequently, the Vfm communication could be impossible between strains possessing different variants of the genes
vfmO/P. We constructed three Vfm QS biosensor strains possessing different
vfmO/P variants and compared these biosensors for their responses to samples prepared from 34
Dickeya strains possessing different
vfmO/P variants. A pattern of specificity was demonstrated, providing evidence that the polymorphism in the genes
vfmO/P determines the biosynthesis of different analogues of the QS signal. Unexpectedly, this
vfmO/P-dependent pattern of specificity is linked to a polymorphism in the ABC transporter gene
vfmG, suggesting an adaptation of the putative permease VfmG to specifically bind different analogues of the QS signal. Accordingly, we discuss the possible involvement of VfmG as co-sensor of the Vfm two-component regulatory system.
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