The function of Asp70, Glu77 and Lys79 in the Escherichia coli MutH protein

Academic Program

Not applicable

UMMS Affiliation

Graduate School of Biomedical Sciences; Department of Biochemistry and Molecular Pharmacology

Publication Date


Document Type



Life Sciences | Medicine and Health Sciences


The MutH protein, which is part of the Dam-directed mismatch repair system of Escherichia coli, introduces nicks in the unmethylated strand of a hemi-methylated DNA duplex. The latent endonuclease activity of MutH is activated by interaction with MutL, another member of the repair system. The crystal structure of MutH suggested that the active site residues include Asp70, Glu77 and Lys79, which are located at the bottom of a cleft where DNA binding probably occurs. We mutated these residues to alanines and found that the mutant proteins were unable to complement a chromosomal mutH deletion. The purified mutant proteins were able to bind to DNA with a hemi-methylated GATC sequence but had no detectable endonuclease activity with or without MutL. Although the data are consistent with the prediction of a catalytic role for Asp70, Glu77 and Lys79, it cannot be excluded that they are also involved in binding to MutL.

DOI of Published Version



Nucleic Acids Res. 2002 Feb 1;30(3):818-22.

Journal/Book/Conference Title

Nucleic acids research

Related Resources

Link to Article in PubMed

PubMed ID