PMID:12799430
| Citation |
Li, L and Lu, AL (2003) The C-terminal domain of Escherichia coli MutY is involved in DNA binding and glycosylase activities. Nucleic Acids Res. 31:3038-49 |
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| Abstract |
Escherichia coli MutY is an adenine and a weak guanine DNA glycosylase involved in reducing mutagenic effects of 7,8-dihydro-8-oxo-guanine (8-oxoG). The C-terminal domain of MutY is required for 8-oxoG recognition and is critical for mutation avoidance of oxidative damage. To determine which residues of this domain are involved in 8-oxoG recognition, we constructed four MutY mutants based on similarities to MutT, which hydrolyzes specifically 8-oxo-dGTP to 8-oxo-dGMP. F294A-MutY has a slightly reduced binding affinity to A/G mismatch but has a severe defect in A/8-oxoG binding at 20 degrees C. The catalytic activity of F294A-MutY is much weaker than that of the wild-type MutY. The DNA binding activity of R249A-MutY is comparable to that of the wild-type enzyme but the catalytic activity is reduced with both A/G and A/8-oxoG mismatches. The biochemical activities of F261A-MutY are nearly similar to those of the wild-type enzyme. The solubility of P262A-MutY was improved as a fusion protein containing streptococcal protein G (GB1 domain) at its N-terminus. The binding of GB1-P262A-MutY with both A/G and A/8-oxoG mismatches are slightly weaker than those of the wild-type protein. The catalytic activity of GB1-P262A-MutY is weaker than that of the wild-type enzyme at lower enzyme concentrations. Importantly, all four mutants can complement mutY mutants in vivo when expressed at high levels; however, F294A, R249A and P262A, but not F261A, are partially defective in vivo when they are expressed at low levels. These results strongly support that the C-terminal domain of MutY is involved not only in 8-oxoG recognition, but also affects the binding and catalytic activities toward A/G mismatches. |
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| Keywords |
Amino Acid Sequence; Binding Sites; DNA/metabolism; DNA Glycosylases; Escherichia coli Proteins/chemistry; Escherichia coli Proteins/genetics; Escherichia coli Proteins/metabolism; Genetic Complementation Test; Models, Molecular; Molecular Sequence Data; Mutation; N-Glycosyl Hydrolases/chemistry; N-Glycosyl Hydrolases/genetics; N-Glycosyl Hydrolases/metabolism; Protein Structure, Tertiary; Sequence Alignment |
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