DOI: 10.1101/463133Nov 5, 2018Paper

The unstructured linker arms of MutL enable GATC site incision beyond roadblocks during initiation of DNA mismatch repair

BioRxiv : the Preprint Server for Biology
Yannicka MardenboroughJoyce H G Lebbink

Abstract

DNA mismatch repair (MMR) maintains genome stability through repair of DNA replication errors. In Escherichia coli, initiation of MMR involves recognition of the mismatch by MutS, recruitment of MutL, activation of endonuclease MutH and DNA strand incision at a hemimethylated GATC site. Here we studied the mechanism of communication that couples mismatch recognition to daughter strand incision. We investigated the effect of catalytically-deficient Cas9 as well as stalled RNA polymerase as roadblocks placed on DNA in between the mismatch and GATC site in ensemble and single molecule nanomanipulation incision assays. The MMR proteins were observed to incise GATC sites beyond a roadblock, albeit with reduced efficiency. This residual incision is completely abolished upon shortening the disordered linker regions of MutL. These results indicate that roadblock bypass can be fully attributed to the long, disordered linker regions in MutL and establish that communication during MMR initiation occurs along the DNA backbone.

Related Concepts

DNA
DNA Repair
Endonuclease
Escherichia coli
Plasmids
DNA-Directed RNA Polymerase
MutS DNA Mismatch-Binding Protein
DNA Sequence
Surgical Incisions
Site

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