Quorum sensing controls biofilm formation in Vibrio cholerae through modulation of cyclic di-GMP levels and repression of vpsT. Author Christopher Waters, Wenyun Lu, Joshua Rabinowitz, Bonnie Bassler Publication Year 2008 Type Journal Article Abstract Two chemical signaling systems, quorum sensing (QS) and 3',5'-cyclic diguanylic acid (c-di-GMP), reciprocally control biofilm formation in Vibrio cholerae. QS is the process by which bacteria communicate via the secretion and detection of autoinducers, and in V. cholerae, QS represses biofilm formation. c-di-GMP is an intracellular second messenger that contains information regarding local environmental conditions, and in V. cholerae, c-di-GMP activates biofilm formation. Here we show that HapR, a major regulator of QS, represses biofilm formation in V. cholerae through two distinct mechanisms. HapR controls the transcription of 14 genes encoding a group of proteins that synthesize and degrade c-di-GMP. The net effect of this transcriptional program is a reduction in cellular c-di-GMP levels at high cell density and, consequently, a decrease in biofilm formation. Increasing the c-di-GMP concentration at high cell density to the level present in the low-cell-density QS state restores biofilm formation, showing that c-di-GMP is epistatic to QS in the control of biofilm formation in V. cholerae. In addition, HapR binds to and directly represses the expression of the biofilm transcriptional activator, vpsT. Together, our results suggest that V. cholerae integrates information about the vicinal bacterial community contained in extracellular QS autoinducers with the intracellular environmental information encoded in c-di-GMP to control biofilm formation. Keywords Models, Biological, Green Fluorescent Proteins, Trans-Activators, Protein Binding, Gene Expression Regulation, Bacterial, Bacterial Proteins, Quorum Sensing, Vibrio cholerae, Flow Cytometry, Biofilms, Cyclic GMP, Electrophoretic Mobility Shift Assay Journal J Bacteriol Volume 190 Issue 7 Pages 2527-36 Date Published 04/2008 Alternate Journal J. Bacteriol. Google ScholarBibTeXEndNote X3 XML