1. Mismatch repair protein hMSH2–hMSH6 recognizes mismatches and forms sliding clamps within a D-loop recombination intermediate
- Author
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Ravindra Amunugama, Maria Spies, Richard Fishel, Shyamal Subramanyam, Masayoshi Honda, Randal J. Soukup, Christopher Cook, Juana Martin-Lopez, Sarah R. Hengel, and Yusuke Okuno
- Subjects
congenital, hereditary, and neonatal diseases and abnormalities ,Base Pair Mismatch ,FLP-FRT recombination ,Biology ,DNA Mismatch Repair ,Genetic recombination ,Adenosine Triphosphate ,Replication Protein A ,Humans ,Biotinylation ,Replication protein A ,Recombination, Genetic ,Genetics ,Multidisciplinary ,Hydrolysis ,DNA ,Mismatch Repair Protein ,digestive system diseases ,Protein Structure, Tertiary ,Cell biology ,Adenosine Diphosphate ,DNA-Binding Proteins ,Non-homologous end joining ,Kinetics ,MutS Homolog 2 Protein ,PNAS Plus ,DNA mismatch repair ,Rad51 Recombinase ,Protein Binding ,Heteroduplex - Abstract
High fidelity homologous DNA recombination depends on mismatch repair (MMR), which antagonizes recombination between divergent sequences by rejecting heteroduplex DNA containing excessive nucleotide mismatches. The hMSH2-hMSH6 heterodimer is the first responder in postreplicative MMR and also plays a prominent role in heteroduplex rejection. Whether a similar molecular mechanism underlies its function in these two processes remains enigmatic. We have determined that hMSH2-hMSH6 efficiently recognizes mismatches within a D-loop recombination initiation intermediate. Mismatch recognition by hMSH2-hMSH6 is not abrogated by human replication protein A (HsRPA) bound to the displaced single-stranded DNA (ssDNA) or by HsRAD51. In addition, ATP-bound hMSH2-hMSH6 sliding clamps that are essential for downstream MMR processes are formed and constrained within the heteroduplex region of the D-loop. Moreover, the hMSH2-hMSH6 sliding clamps are stabilized on the D-loop by HsRPA bound to the displaced ssDNA. Our findings reveal similarities and differences in hMSH2-hMSH6 mismatch recognition and sliding-clamp formation between a D-loop recombination intermediate and linear duplex DNA.
- Published
- 2014