The Formation of a Stable Sliding Clamp Discriminates MSH2-MSH3 and MSH2-MSH6 Mismatch Interaction
Year: 2021
Type: preprint
Abstract: ABSTRACT MutS homologs (MSH) are highly conserved core components of DNA mismatch repair (MMR). Mismatch recognition provokes ATP-binding by MSH proteins that drives a conformational transition from a short-lived lesion-searching clamp to an extremely stable sliding clamp on the DNA. Once on DNA the MSH sliding clamps provide a platform for the assembly of MMR strand-specific excision components beginning with the highly conserved MutL homologs (MLH/PMS). Previous studies with short mismatch-containing oligonucleotides revealed an MSH ATP hydrolysis (ATPase) cycle that included mismatch recognition, the formation of an ATP-bound sliding clamp and dissociation from the end of a mismatched DNA that ultimately recovers the mismatch binding conformation. We found that ATP-bound MSH complexes on blocked-end or very long DNA are extremely stable under a range of ionic conditions. These observations underpinned the development of a high-throughput fluorescence resonance energy transfer (FRET) system capable of clearly distinguishing between HsMSH2-HsMSH3 and HsMSH2-HsMSH6 activities that is suitable for chemical inhibitor screens.
Authors: Brooke M. Britton, James A. London, Juana Martin-Lopez, Nathan D. Jones, Jiaquan Liu, Jong-Bong Lee, Richard Fishel
Language: English
Topic: DNA Repair Mechanisms
Subfield: Molecular Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W3207495161