Pseudomonas Virulence Factor Produces Autoinducer (S)-Valdiazen.

Pseudomonas virulence factor (pvf) produces an autoinducing small-molecule signal that regulates bacterial cell-to-cell communication and virulence. While genes like pvf have been linked to the production of small molecules containing a diazeniumdiolate group, the specific chemical signal produced by pvf had not been identified. In this study, we reveal that (S)-valdiazen is the autoinducer produced by pvf in Pseudomonas entomophila, a model for pathogen-host interactions. The (S)-configuration is crucial for the signaling activity of valdiazen at physiological concentrations. We also define the (S)-stereochemistry of leudiazen, a similar signal produced by the plant pathogen Pseudomonas syringae. Using pvf genes needed for (S)-valdiazen signaling and production in P. entomophila, we bioinformatically identified 5383 bacterial organisms that may produce diazeniumdiolate signals. Signaling activity of valdiazen can be quenched by potassium permanganate, which oxidizes the diazeniumdiolate moiety. Identification of (S)-diazeniumdiolates from two bacterial species suggests stereospecific biosynthesis and transduction of these signals. Our findings set the stage for discovering diazeniumdiolate signals from other bacteria.