Escherichia coli Lacking RpoS Are Rare in Natural Populations of Non-Pathogens

G3: Genes, Genomes, Genetics

Emily Snyder²  Daniel M. Stoebel²  David M. Gordon¹ 

[1] Research School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, AustraliResearch School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, AustraliResearch School of Biology, Australian National University, Canberra, Australian Capital Territory 0200, Australi;Department of Biology, Harvey Mudd College, Claremont California 91711Department of Biology, Harvey Mudd College, Claremont California 91711Department of Biology, Harvey Mudd College, Claremont California 91711

关键词: SPANC;    population genetics;    variation;    transcription factor;   

DOI  :  10.1534/g3.112.003855

学科分类：生物科学（综合）

来源: Genetics Society of America

【 摘 要 】

The alternative sigma factor RpoS controls a large regulon that allows E. coli to respond to a variety of stresses. Mutations in rpoS can increase rates of nutrient acquisition at the cost of a decrease in stress resistance. These kinds of mutations evolve rapidly under certain laboratory conditions where nutrient acquisition is especially challenging. The frequency of strains lacking RpoS in natural populations of E. coli is less clear. Such strains have been found at frequencies over 20% in some collections of wild isolates. However, laboratory handling can select for RpoS-null strains and may have affected some of these strain collections. Other studies have included an unknown diversity of strains or only used a phenotypic proxy as a measure of RpoS levels. We directly measured RpoS levels in a collection of E. coli that includes the full diversity of the species and that was handled in a manner to minimize the potential for laboratory evolution. We found that only 2% of strains produce no functional RpoS. Comparison of these strains in multiple labs shows that these rpoS mutations occurred in the laboratory. Earlier studies reporting much higher levels of RpoS polymorphism may reflect the storage history of the strains in laboratories rather than true frequency of such strains in natural populations.

【 授权许可】

Unknown