The σE stress response is required for stress‐induced mutation and amplification in Escherichia coli |
| |
| Authors: | Janet L Gibson Mary‐Jane Lombardo Philip C Thornton Kenneth H Hu Rodrigo S Galhardo Bernadette Beadle Anand Habib Daniel B Magner Laura S Frost Christophe Herman P J Hastings Susan M Rosenberg |
| |
| Institution: | 1. Department of Molecular and Human Genetics,;2. Present addresses: The J. Craig Venter Institute, San Diego, CA 92121, USA;3. Massachusetts Institute of Technology, Cambridge, MA, USA;4. Department of Microbiology, University of Sao Paulo, Sao Paulo, Brazil;5. Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada.;6. Stanford University, Palo Alto, CA, USA;7. Max‐Plank‐Institute for Biology of Ageing, Gleueler Stra?e 50a, D‐50931 Cologne, Germany.;8. Department of Molecular Virology and Microbiology,;9. Department of Biochemistry and Molecular Biology, and;10. The Dan L Duncan Cancer Center, Baylor College of Medicine, Houston, TX 77030‐3411, USA. |
| |
| Abstract: | Pathways of mutagenesis are induced in microbes under adverse conditions controlled by stress responses. Control of mutagenesis by stress responses may accelerate evolution specifically when cells are maladapted to their environments, i.e. are stressed. Stress‐induced mutagenesis in the Escherichia coli Lac assay occurs either by ‘point’ mutation or gene amplification. Point mutagenesis is associated with DNA double‐strand‐break (DSB) repair and requires DinB error‐prone DNA polymerase and the SOS DNA‐damage‐ and RpoS general‐stress responses. We report that the RpoE envelope‐protein‐stress response is also required. In a screen for mutagenesis‐defective mutants, we isolated a transposon insertion in the rpoE P2 promoter. The insertion prevents rpoE induction during stress, but leaves constitutive expression intact, and allows cell viability. rpoE insertion and suppressed null mutants display reduced point mutagenesis and maintenance of amplified DNA. Furthermore, σE acts independently of stress responses previously implicated: SOS/DinB and RpoS, and of σ32, which was postulated to affect mutagenesis. I‐SceI‐induced DSBs alleviated much of the rpoE phenotype, implying that σE promoted DSB formation. Thus, a third stress response and stress input regulate DSB‐repair‐associated stress‐induced mutagenesis. This provides the first report of mutagenesis promoted by σE, and implies that extracytoplasmic stressors may affect genome integrity and, potentially, the ability to evolve. |
| |
| Keywords: | |
|
|
