Editor: Jeff Cole
mutL as a genetic switch of bacterial mutability: turned on or off through repeat copy number changes
Version of Record online: 27 SEP 2010
© 2010 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved
FEMS Microbiology Letters
Volume 312, Issue 2, pages 126–132, November 2010
How to Cite
Chen, F., Liu, W.-Q., Liu, Z.-H., Zou, Q.-H., Wang, Y., Li, Y.-G., Zhou, J., Eisenstark, A., Johnston, R. N., Liu, G.-R., Yang, B.-F. and Liu, S.-L. (2010), mutL as a genetic switch of bacterial mutability: turned on or off through repeat copy number changes. FEMS Microbiology Letters, 312: 126–132. doi: 10.1111/j.1574-6968.2010.02107.x
- Issue online: 19 OCT 2010
- Version of Record online: 27 SEP 2010
- Accepted manuscript online: 2 SEP 2010 09:31AM EST
- Received 17 April 2010; revised 14 August 2010; accepted 24 August 2010.Final version published online 27 September 2010.
- genetic switch
Bacterial adaptation to changing environments can be achieved through the acquisition of genetic novelty by accumulation of mutations and recombination of laterally transferred genes into the genome, but the mismatch repair (MMR) system strongly inhibits both these types of genetic changes. As mutation and recombination do occur in bacteria, it is of interest to understand how genetic novelty may be achieved in the presence of MMR. Previously, we observed associations of a defective MMR genotype, 6bpΔmutL, with greatly elevated bacterial mutability in Salmonella typhimurium. To validate these observations, we experimentally converted the mutL gene between the wild-type and 6bpΔmutL in S. typhimurium and inspected the bacterial mutability status. When 6bpΔmutL was converted to mutL, the originally highly mutable Salmonella strains regained genetic stability; when mutL was converted to 6bpΔmutL, the mutability was elevated 100-fold. Interestingly, mutL cells were found to grow out of 6bpΔmutL cells; the new mutL cells eventually replaced the original 6bpΔmutL population. As conversion between mutL and 6bpΔmutL may occur readily during DNA replication, it may represent a previously unrecognized mechanism to modulate bacterial mutability at the population level, allowing bacteria to respond rapidly to changing environments while minimizing the risks associated with persistent hypermutability.