Title: Small RNA Regulation of Quorum Sensing in Vibrios

Speaker： Dr. Lihui Feng

             Department of Pathology and Immunology, School of Medicine, Washington University in St. Louis

Time： 1:00pm Mar 25th 2015

Address： Rm 101, East wing of Old Chemistry Building, Peking Unversity 

Chair：  Prof. Chao Tang,  Center for Quantitative Biology 

Abstract：

     Quorum sensing is a cell-cell communication process that bacteria use to transition between individual and social lifestyles. In vibrios, homologous small RNAs called the QrrsRNAs function at the center of quorum-sensing pathways. The QrrsRNAs regulate multiple mRNA targets including those encoding the quorum-sensing regulatory components luxR, luxO, luxM, and aphA. Combining bacterial genetics and biochemistry,I found that a representative Qrr, Qrr3, uses four distinct mechanisms to control its particular targets: the Qrr3 sRNA represses luxR through catalytic degradation, represses luxM through coupled degradation, represses luxO through sequestration, and activates aphA by revealing the ribosome binding site while the sRNA itself is degraded. Qrr3 forms different base-pairing interactions with each mRNA target, and the particular pairing strategy determines which regulatory mechanism occurs. Combined mathematical modeling and experiments show that the specific Qrr regulatory mechanism employed governs the potency, dynamics, and competition of target mRNA regulation, which in turn, defines the overall quorum-sensing response.