Monster Seminar JAM - Widespread Adaptive Mutations in Bacterial Genomes
Dr. Sujay Chattopadhyay, Microbiology, University of Washington
Bacteria, as they frequently face environmental pressures or inter-/intra-species competitions, try to get an edge in the situation through adaptation at the molecular level. Structural mutation in DNA, being responsible for the change in protein function, is a major force of such molecular level adaptive evolution. Repeated independent occurrences of structural mutations in the same amino acid positions hotspot mutations represent a strong marker of adaptive evolution. In Escherichia coli and Salmonella enterica, we determined high frequency of hotspot mutations, widespread even in core genes that comprise the ubiquitous backbone of bacterial genomes and generally are not thought to contribute to the adaptive evolution. Pathogenic strains, as opposed to non-pathogenic ones, accumulate hotspot mutations at significantly higher rate, suggesting the adaptive nature of such mutations. The vast majority of hotspot mutations are of recent evolutionary origin, implying short-term positive selection, where adaptive mutations emerge repeatedly but are not sustained in natural circulation for long.
Date and Time:
September 30, 2010,
11:00 am - 12:00 pm