Atomic force microscopy captures the initiation of methyl-directed DNA mismatch repair.

Journal Article

In Escherichia coli, errors in newly-replicated DNA, such as the incorporation of a nucleotide with a mis-paired base or an accidental insertion or deletion of nucleotides, are corrected by a methyl-directed mismatch repair (MMR) pathway. While the enzymology of MMR has long been established, many fundamental aspects of its mechanisms remain elusive, such as the structures, compositions, and orientations of complexes of MutS, MutL, and MutH as they initiate repair. Using atomic force microscopy, we--for the first time--record the structures and locations of individual complexes of MutS, MutL and MutH bound to DNA molecules during the initial stages of mismatch repair. This technique reveals a number of striking and unexpected structures, such as the growth and disassembly of large multimeric complexes at mismatched sites, complexes of MutS and MutL anchoring latent MutH onto hemi-methylated d(GATC) sites or bound themselves at nicks in the DNA, and complexes directly bridging mismatched and hemi-methylated d(GATC) sites by looping the DNA. The observations from these single-molecule studies provide new opportunities to resolve some of the long-standing controversies in the field and underscore the dynamic heterogeneity and versatility of MutSLH complexes in the repair process.

Full Text

Duke Authors

Cited Authors

  • Josephs, EA; Zheng, T; Marszalek, PE

Published Date

  • November 2015

Published In

Volume / Issue

  • 35 /

Start / End Page

  • 71 - 84

PubMed ID

  • 26466357

Electronic International Standard Serial Number (EISSN)

  • 1568-7856

International Standard Serial Number (ISSN)

  • 1568-7864

Digital Object Identifier (DOI)

  • 10.1016/j.dnarep.2015.08.006

Language

  • eng