MC 5479
Speaker
Geoffrey Hunter, Ontario Institute for Cancer Research
Title
The role of small RNA in quorum sensing
Abstract
Quorum sensing is a process by which bacteria coordinate expression of their genes based on the local cell-population density. Up to five small noncoding RNAs (sRNA) in the quorum sensing system ofVibrio harveyi and Vibrio cholerae regulate expression of the master transcriptional regulator protein, LuxR (V. harveyi) and HapR (V. cholerae). LuxR/HapR, in turn, regulate downstream genes associated with virulence and bioluminescence. Interestingly, the V. harveyi and V. cholerae quorum sensing systems are topologically identical and their components homologous, yet they respond differently to identical experimental conditions. The leading hypothesis suggests that the phenotypic differences arise from tuning differences in the feedback governing sRNA synthesis.
In this work, I formulate and parameterize a novel model of the V. harveyi and V. cholerae quorum sensing system to identify parametric differences underlying their phenotypic differences. Contrary to the leading hypothesis, analysis of the parameterized model shows that feedback is neither necessary nor sufficient to explain these differences. Rather, I argue that the phenotypes are an emergent phenomena and, in the case of V. harveyi and V. cholerae, reflect differences in the saturation of the protein chaperone Hfq with sRNA. Overall, this suggests an important biological role for Hfq modulating sRNA-facilitated repression of target mRNA.
Biography
Geoffrey Hunter is a postdoctoral fellow at the Ontario Institute for Cancer Research (OICR) in Toronto, Ontario where his work focuses on developing prognostic biomarkers for patients with prostate cancer. His other research interests include developing tools for automated histology analysis and exploring citizen science solutions to big data problems. He holds a Ph.D. and M.Sc. in Mathematics from the University of Utah where he studied under James P. Keener. He also holds a B.Math (Honours Applied Math, Co-op) from the University of Waterloo where he was an active member in the Mathematical Medicine and Biology group working under the supervision of S. Sivaloganathan and G. Tenti.