PMID:10871405
| Citation |
Nakahara, T, Zhang, QM, Hashiguchi, K and Yonei, S (2000) Identification of proteins of Escherichia coli and Saccharomyces cerevisiae that specifically bind to C/C mismatches in DNA. Nucleic Acids Res. 28:2551-6 |
|---|---|
| Abstract |
The pathways leading to G:C-->C:G transversions and their repair mechanisms remain uncertain. C/C and G/G mismatches arising during DNA replication are a potential source of G:C-->C:G transversions. The Escherichia coli mutHLS mismatch repair pathway efficiently corrects G/G mismatches, whereas C/C mismatches are a poor substrate. Escherichia coli must have a more specific repair pathway to correct C/C mismatches. In this study, we performed gel-shift assays to identify C/C mismatch-binding proteins in cell extracts of E. COLI: By testing heteroduplex DNA (34mers) containing C/C mismatches, two specific band shifts were generated in the gels. The band shifts were due to mismatch-specific binding of proteins present in the extracts. Cell extracts of a mutant strain defective in MutM protein did not produce a low-mobility complex. Purified MutM protein bound efficiently to the C/C mismatch-containing heteroduplex to produce the low-mobility complex. The second protein, which produced a high-mobility complex with the C/C mismatches, was purified to homogeneity, and the amino acid sequence revealed that this protein was the FabA protein of E.COLI: The high-mobility complex was not formed in cell extracts of a fabA mutant. From these results it is possible that MutM and FabA proteins are components of repair pathways for C/C mismatches in E.COLI: Furthermore, we found that Saccharomyces cerevisiae OGG1 protein, a functional homolog of E.COLI: MutM protein, could specifically bind to the C/C mismatches in DNA. |
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| Keywords |
Adenosine Triphosphatases; Bacterial Proteins/genetics; Bacterial Proteins/metabolism; Base Pair Mismatch/genetics; Binding Sites; Cytosine/metabolism; DNA/chemistry; DNA/genetics; DNA/metabolism; DNA-Binding Proteins/chemistry; DNA-Binding Proteins/genetics; DNA-Binding Proteins/isolation & purification; DNA-Binding Proteins/metabolism; DNA-Formamidopyrimidine Glycosylase; Escherichia coli/cytology; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins; Fatty Acid Synthetase Complex, Type II; Hydro-Lyases/genetics; Hydro-Lyases/isolation & purification; Hydro-Lyases/metabolism; Molecular Weight; MutS DNA Mismatch-Binding Protein; Mutation/genetics; N-Glycosyl Hydrolases/genetics; N-Glycosyl Hydrolases/isolation & purification; N-Glycosyl Hydrolases/metabolism; Nucleic Acid Heteroduplexes/chemistry; Nucleic Acid Heteroduplexes/genetics; Nucleic Acid Heteroduplexes/metabolism; Saccharomyces cerevisiae/enzymology; Saccharomyces cerevisiae/genetics; Sequence Homology, Amino Acid; Substrate Specificity |
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