The Pseudomonas virulence factor, pvf biosynthetic operon has been implicated in bacterial virulence and signaling. Researchers in the Li Lab, published in the journal Biochemistry, as part of the Current Topics in Mechanistic Enzymology 2019, identify 308 bacterial strains containing pvf homologues that likely produce signaling molecules with distinct structures and biological activities. Several homologues of the nonribosomal peptide synthetase, NRPS, pvfC, were biochemically characterized and shown to activate L-Val or L-Leu. The amino acid selectivity of pvfC and its homologues likely direct pvf signaling activity.
The team of researchers explored the natural diversity of the active site residues present in 92% of the adenylation domains of pvfC homologues and identified key residues for substrate selection and catalysis. Sequence similarity network, SSN, analysis revealed grouping of pvfC homologues that harbor the same active site residues and activate the same amino acids.
This work combines cellular, bioinformatic, and biochemical studies to define the adenylating activities of a family of NRPSs that result in two distinct types of signaling molecules and to identify active site residues of these NRPSs that are essential for substrate specificity. This work also advances the understanding of a key biosynthetic step in a widespread signaling pathway.