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Spontaneous mutation rates rise in ‘lonely’ mutating microbes

Thursday 4 October 2018, 1.00PM

Speaker(s): Dr Rok Krasovec, Manchester

Evolution depends on mutations. In microbes, the rate at which mutations arise is known to increase with various stressors (stress-induced mutagenesis—SIM) and decrease at high final population density (density-associated mutation-rate plasticity—DAMP). As lead author I have shown that DAMP is environmentally, ecologically and even socially-dependent variable. We found DAMP in 70 years of published literature, analysing mutation rates of 26 microbial species, including viruses. DAMP depends on MutT protein, a nudix hydrolase that scavenges mutagenic 8-oxo-dGTP from the nucleotide pool in both bacteria and yeast. We distinguish an increase in mutation rate with added nutrients through SIM (dependent on error-prone polymerases Pol IV and Pol V) and an opposing effect of DAMP. The combination of DAMP and SIM results in a mutation rate minimum at intermediate nutrient levels. My work is novel, demonstrating a strikingly close and nuanced relationship of ecological factors—stress and population density—with mutation. I anticipate that DAMP affects the course of evolution more generally and understanding its causes and effects will help understand and control evolutionary trajectories.

Location: K018