An aryl-homoserine lactone quorum-sensing signal produced by a dimorphic prosthecate bacterium
Lisheng Liao, Amy L. Schaefer, Bruna G. Coutinho, Pamela J. B. Brown, and E. Peter Greenberg
2 July 2018, PNAS 115(29):7587-7592; doi: 10.1073/pnas.1808351115
Many species of Proteobacteria produce acyl-homoserine lactone (AHL) compounds as quorum-sensing (QS) signals for cell density dependent gene regulation. Most known AHL synthases, LuxI-type enzymes, produce fatty AHLs, and the fatty acid moiety is derived from an acyl-acyl carrier protein (ACP) intermediate in fatty acid biosynthesis. Recently, a class of LuxI homologs has been shown to use CoA-linked aromatic or amino acid substrates for AHL synthesis. By using an informatics approach, we found the CoA class of LuxI homologs exists primarily in α-Proteobacteria. The genome of Prosthecomicrobium hirschii, a dimorphic prosthecate bacterium, possesses a luxI-like AHL synthase gene that we predicted to encode a CoA-utilizing enzyme. We show the P. hirschii LuxI homolog catalyzes synthesis of phenylacetyl-homoserine lactone (PA-HSL). Our experiments show P. hirschii obtains phenylacetate from its environment and uses a CoA ligase to produce the phenylacetyl-CoA substrate for the LuxI homolog. By using an AHL degrading enzyme, we showed that PA-HSL controls aggregation, biofilm formation, and pigment production in P. hirschii. These findings advance a limited understanding of the CoA-dependent AHL synthases. We describe how to identify putative members of the class, we describe a signal synthesized by using an environmental aromatic acid, and we identify phenotypes controlled by the aryl-HSL.
Liao, L., A. L. Schaefer, B. G. Coutinho, P. J. B. Brown and E. P. Greenberg (2018). “An aryl-homoserine lactone quorum-sensing signal produced by a dimorphic prosthecate bacterium.” Proc Natl Acad Sci U S A 115(29): 7587-7592.