Liao, L. et al., 2018. PNAS

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
17 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.

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