Dataset Open Access

Recurrent mismatch binding by MutS mobile clamps on DNA localizes repair complexes nearby

Weninger, Keith; Hao, Pengyu; LeBlanc, Sharonda J.; Case, Brandon C.; Elston, Timothy C.; Hingorani, Manju M.; Erie, Dorothy A.

DNA mismatch repair (MMR), the guardian of the genome, commences when MutS identifies a mismatch and recruits MutL to nick the error-containing strand, allowing excision and DNA resynthesis. Dominant MMR models posit that after mismatch recognition, ATP converts MutS to a hydrolysis-independent, diffusive mobile clamp that no longer recognizes the mismatch. Little is known about the postrecognition MutS mobile clamp and its interactions with MutL. Two disparate frameworks have been proposed: One in which MutS–MutL complexes remain mobile on the DNA, and one in which MutL stops MutS movement. Here we use single-molecule FRET to follow the postrecognition states of MutS and the impact of MutL on its properties. In contrast to current thinking, we find that after the initial mobile clamp formation event, MutS undergoes frequent cycles of mismatch rebinding and mobile clamp reformation without releasing DNA. Notably, ATP hydrolysis is required to alter the conformation of MutS such that it can recognize the mismatch again instead of bypassing it; thus, ATP hydrolysis licenses the MutS mobile clamp to rebind the mismatch. Moreover, interaction with MutL can both trap MutS at the mismatch en route to mobile clamp formation and stop movement of the mobile clamp on DNA. MutS's frequent rebinding of the mismatch, which increases its residence time in the vicinity of the mismatch, coupled with MutL's ability to trap MutS, should increase the probability that MutS–MutL MMR initiation complexes localize near the mismatch.

 

This contains single molecule FRET (smFRET) data following the post-recognition state(s) of MutS and the impact of MutL on its properties.

Funding provided by: National Institute of General Medical Sciences
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000054
Award Number: GM109832

Funding provided by: National Cancer Institute
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000054
Award Number: CA218304

Funding provided by: National Institute of General Medical Sciences**
Crossref Funder Registry ID:
Award Number: GM079480

Funding provided by: National Institute of General Medical Sciences*
Crossref Funder Registry ID:
Award Number: GM114743

Funding provided by: National Institute of General Medical Sciences*
Crossref Funder Registry ID:
Award Number: GM127145

Funding provided by: National Institute of General Medical Sciences
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000057
Award Number: GM123602

Funding provided by: National Institute of General Medical Sciences
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000057
Award Number: GM127151

Funding provided by: National Institute of General Medical Sciences
Crossref Funder Registry ID: http://dx.doi.org/10.13039/100000057
Award Number: GM132263

Funding provided by: National Institute of General Medical Sciences
Award Number: GM123602

Funding provided by: National Institute of General Medical Sciences
Award Number: GM132263

Funding provided by: National Institute of General Medical Sciences
Award Number: GM079480

Funding provided by: National Institute of General Medical Sciences
Award Number: GM114743

Funding provided by: National Institute of General Medical Sciences
Award Number: GM127145

Funding provided by: National Institute of General Medical Sciences
Award Number: GM127151

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