Editors' ChoiceMicrobiology

Quorum Sensing a New Way

Science's STKE  08 Jan 2002:
Vol. 2002, Issue 114, pp. tw6
DOI: 10.1126/stke.2002.114.tw6

Bacteria can detect their density and alter their behavior based on the accumulation and detection of secreted signaling molecules in a process called quorum sensing. Haas et al. showed that, in Enterococcus faecalis, the toxin cytolysin acts to induce its own production through a quorum-sensing signaling cascade. The quorum-sensing and increased transcriptional activity of the operon requires the presence of two genes (cylR1 and cylR2), located upstream of the cytolysin operon and oriented opposite to the operon for the purposes of expression. These two genes encode novel proteins: cylR1 encodes a protein with three predicted transmembrane helices (the putative receptor), and cylR2 encodes a protein with a helix-turn-helix DNA binding motif (the putative response regulator). Using a reporter construct, Haas et al. showed that mutation of deletion of either of cylR1or cylR2 resulted in constitutive activity of the cyl promoter and loss of cytolysin-stimulated increase in gene expression. Dunny discusses how this cytolysin pathway represents a third mechanism for quorum-sensing, in addition to the known two-component histidine kinase pathways and the import to intracellular receptor signaling pathways.

W. Haas, B. D. Shepard, M. S. Gilmore, Two-component regulator of Enterococcus faecalis cytolysin responds to quorum-sensing autoinduction. Nature 415, 84-87 (2002). [Online Journal]

G. M. Dunny, Group effort in toxin synthesis. Nature 415, 33-34 (2002). [Online Journal]