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#MutS

2 public questions tagged with this topic.

Repair Pathway

Mismatch repair in eukaryotes lacks

Eukaryotic mismatch repair retains conserved MutS homologs MSH2/MSH6 for mismatch recognition and MutL homologs MLH1/PMS2 for coordination, but lacks MutH ortholog entirely. Strand discrimination does not depend on Dam methylation, absent in eukaryotes. Instead, naturally occurring nicks associated with lagging strand Okazaki fragment termini, leading strand replication discontinuities, or PCNA-bound MutL endonuclease activity create entry points for EXO1 exonuclease. MutLα itself displays latent endonuclease regulated by PCNA and ATP. Therefore, eukaryotic system achieves directionality witho

Ref: NCBI Bookshelf DNA Mismatch Repair in Eukaryotes No MutH; Lodish Molecular Cell Biology 9th ed. Chapter 11 Eukaryotic MMR differences

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Repair Pathway

Which protein recognizes mismatch in E. coli?

MutS functions as initial mismatch sensor in E. coli mismatch repair pathway. Homodimeric ATPase encircles DNA, conducting diffusive scanning and interrogating duplex for wobble pairing or small insertion-deletion loops that distort helix geometry. Upon encountering mismatch, MutS undergoes ATP-dependent conformational change, kinking DNA about 60 degrees and forming transient sliding clamp. This activated form recruits MutL connector protein, coordinating downstream cleavage and excision steps. Without MutS recognition, proofreading escape errors persist. Homologs MSH2-MSH6 perform analogous

Ref: Lodish et al., Molecular Cell Biology, 9th ed., Chapter 11: MutS mismatch recognition and ATPase; Nature Commun. 2021 MutS clamp loader model

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