Disruption of protein-protein interaction hotspots in the C-terminal domain of MLH1 confers mismatch repair deficiency.

ABSTRACT: MutLα, a heterodimer of MLH1 and PMS2, plays a key role in DNA mismatch repair (MMR), which maintains genomic stability by correcting replication errors. Loss of MLH1 function causes MMR deficiency (MMRd), leading to elevated mutation rates and increased cancer susceptibility. However, MMRd can offer a therapeutic advantage, as high tumour mutational burden enhances the efficacy of immune checkpoint inhibition. MMR also drives somatic expansion of CAG repeats linked to Huntington's disease (HD) pathogenesis. The C-terminal domain (CTD) of MLH1 contains at least two distinct protein-protein interaction (PPI) sites. The S1 site supports heterodimerization with the PMS2 endonuclease, whereas the S2 site interacts with MIP-boxes present in MMR-associated factors (EXO1, MSH3) and in the DNA rep

SUBMITTER: Fishwick KM 

PROVIDER: S-EPMC12754775 | biostudies-literature | 2025 Dec

REPOSITORIES: biostudies-literature