A new class of homoserine lactone quorum-sensing signals

Amy L. Schaefer et al. Nature. Published online: 18 June 2008

Speaker: Po-Pin Hung (洪伯斌)                                     Time: 14:00~15:00, Dec. 3, 2008

Commentator: Dr. Pei-Jane Tsai (蔡佩珍老師)       Place: Room 601

Abstract：

Prokaryotes, such as the bacteria, possess certain mechanism regarding the interaction to environmental change, including insufficient nutrition, change in temperature, humidity, and balance of acid and base. Besides, they also have so-called “ Quorum sensing “, one mechanism used to response to cell-to-cell communication that alters gene expression. In addition, this mechanism also engenders cell-density-dependent gene expression via several mediators.

Bacteria utilize acyl-homoserine lactone (acyl-HSL) synthases to generate fatty acyl-HSL quorum-sensing signals, which function with signal receptors to control expression of specific genes. To date, the only known fatty acyl group is derived from fatty acid biosynthesis and provides signal specificity. In this article, we present that the photosynthetic bacterium Rhodopseudomonas palustris uses an acyl-HSL synthase to produce p-coumaroyl-HSL by using environmental p-coumaric acid (originated from many plants) instead of fatty acids from cellular pools. Intrestinmg, this bacterium also has a signal receptor with homology to fatty acyl-HSL receptors that responds to p-coumaroyl-HSL to regulate global gene expression.

        This new kind of quorum-sensing signals is not unique in the bacterium only, we also found that p-coumaroyl-HSL is made by other bacteria including Bradyrhizobium sp. and Silicibacter pomeroyi. This newly-known finding opens up the range of possibilities for acyl-HSL quorum sensing.

References：

1.      Schaefer, A. L., Hanzelka, B. L., Parsek, M. R. & Greenberg, E. P. Detection, purification, and structural elucidation of the acylhomoserine lactone inducer of Vibrio fischeri luminescence and other related molecules. Methods Enzymol. 305, 288–301 (2000).

2.      Parsek, M. R., Val, D. L., Hanzelka, B. L., Cronan, J. E. Jr & Greenberg, E. P. Acyl homoserine-lactone quorum-sensing signal generation. Proc. Natl Acad. Sci. USA 96, 4360–4365 (1999).