Quorum Sensing Feedback Loops in Vibrio Harveyi: A Computational Model

Abstract

Quorum sensing is the process that allows bacteria to synchronize their behavior in response to changes in cell density. In the marine bacterium Vibrio harveyi, quorum sensing regulated traits such as bioluminescence are controlled by a set of regulatory feedback loops mediated by 5 small non-coding RNAs called Qrr1-5. The Qrr sRNAs do not behave identically, and I will show that a single base pair mutation in Qrr1, located in the conserved region that is used for pairing with mRNA targets, causes diminished repression of key targets. I will present a quantitative model of the Qrr mediated feedback loops which accurately predicts the relative ability of different Qrr sRNAs to regulate the high cell density master regulator LuxR. This model can be used to understand the complex interactions between the sRNA and mRNA species involved in quorum sensing and, in particular, to probe the sensitivity of the system to changes in the Qrr sRNAs.