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DnaN clamp zones provide a platform for spatiotemporal coupling of mismatch detection to DNA replication
Author(s) -
Lenhart Justin S.,
Sharma Anushi,
Hingorani Manju M.,
Simmons Lyle A.
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12115
Subject(s) - replisome , processivity , biology , dna replication , dna mismatch repair , microbiology and biotechnology , dna , dna repair , genetics , eukaryotic dna replication
Summary Mismatch repair ( MMR ) increases the fidelity of DNA replication by identifying and correcting replication errors. Processivity clamps are vital components of DNA replication and MMR , yet the mechanism and extent to which they participate in MMR remains unclear. We investigated the role of the B acillus subtilis processivity clamp DnaN , and found that it serves as a platform for mismatch detection and coupling of repair to DNA replication. By visualizing functional MutS fluorescent fusions in vivo , we find that MutS forms foci independent of mismatch detection at sites of replication (i.e. the replisome). These MutS foci are directed to the replisome by DnaN clamp zones that aid mismatch detection by targeting the search to nascent DNA . Following mismatch detection, MutS disengages from the replisome, facilitating repair. We tested the functional importance of DnaN ‐mediated mismatch detection for MMR , and found that it accounts for 90% of repair. This high dependence on DnaN can be bypassed by increasing MutS concentration within the cell, indicating a secondary mode of detection in vivo whereby MutS directly finds mismatches without associating with the replisome. Overall, our results provide new insight into the mechanism by which DnaN couples mismatch recognition to DNA replication in living cells.