β Clamp Directs Localization of Mismatch Repair in Bacillus subtilis

[摘要] MutS homologs function in several cellular pathways including mismatch repair (MMR), the process by which mismatches introduced during DNA replication are corrected. We demonstrate that the C terminus of Bacillus subtilis MutS is necessary for an interaction with β clamp. This interaction is required for MutS-GFP focus formation in response to mismatches. Reciprocally, we show that a mutant of the β clamp causes elevated mutation frequencies and is reduced for MutS-GFP focus formation. MutS mutants defective for interaction with β clamp failed to support the next step of MMR, MutL-GFP focus formation. We conclude that the interaction between MutS and β is the major molecular interaction facilitating focus formation and that β clamp aids in the stabilization of MutS at a mismatch in vivo. The striking ability of the MutS C terminus to direct focus formation at replisomes by itself, suggests that it is mismatch recognition that licenses MutS;;s interaction with β clamp.

[发布机构] Elsevier