Abstract
DNA mismatch repair ensures genomic stability by correcting biosynthetic errors and by blocking homologous recombination. MutS-like and MutL-like proteins play important roles in these processes. In Escherichia coli and yeast these two types of proteins form a repair initiation complex that binds to mismatched DNA. However, whether human MutS and MutL homologs interact to form a complex has not been elucidated. Using immunoprecipitation and Western blot analysis we show here that human MSH2, MLH1, PMS2 and proliferating cell nuclear antigen (PCNA) can be co-immunoprecipitated, suggesting formation of a repair initiation complex among these proteins. Formation of the initiation complex is dependent on ATP hydrolysis and at least functional MSH2 and MLH1 proteins, because the complex could not be detected in tumor cells that produce truncated MLH1 or MSH2 protein. We also demonstrate that PCNA is required in human mismatch repair not only at the step of repair initiation, but also at the step of repair DNA re-synthesis.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Adaptor Proteins, Signal Transducing
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Adenosine Triphosphatases*
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Adenosine Triphosphate / metabolism*
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Base Sequence
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Carrier Proteins
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Cell Line
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DNA / biosynthesis
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DNA / genetics
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DNA Repair / genetics
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DNA Repair / physiology*
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DNA Repair Enzymes*
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DNA-Binding Proteins*
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HeLa Cells
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Humans
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Hydrolysis
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Mismatch Repair Endonuclease PMS2
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MutL Protein Homolog 1
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MutS Homolog 2 Protein
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Neoplasm Proteins / isolation & purification
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Neoplasm Proteins / metabolism
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Nuclear Proteins
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Oligonucleotide Probes / genetics
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Precipitin Tests
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Proliferating Cell Nuclear Antigen / isolation & purification
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Proliferating Cell Nuclear Antigen / metabolism*
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Proteins / isolation & purification
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Proteins / metabolism
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Proto-Oncogene Proteins / isolation & purification
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Proto-Oncogene Proteins / metabolism
Substances
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Adaptor Proteins, Signal Transducing
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Carrier Proteins
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DNA-Binding Proteins
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MLH1 protein, human
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Neoplasm Proteins
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Nuclear Proteins
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Oligonucleotide Probes
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Proliferating Cell Nuclear Antigen
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Proteins
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Proto-Oncogene Proteins
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Adenosine Triphosphate
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DNA
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Adenosine Triphosphatases
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PMS2 protein, human
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MSH2 protein, human
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Mismatch Repair Endonuclease PMS2
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MutL Protein Homolog 1
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MutS Homolog 2 Protein
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DNA Repair Enzymes