GSBS Student Publications

Title

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

UMMS Affiliation

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

Date

1-26-2002

Document Type

Article

Medical Subject Headings

*Adenosine Triphosphatases; Amino Acid Substitution; Aspartic Acid; Bacterial Proteins; Base Sequence; Binding Sites; Catalysis; DNA; *DNA Repair Enzymes; DNA-Binding Proteins; Electrophoretic Mobility Shift Assay; Endodeoxyribonucleases; Escherichia coli; Escherichia coli Proteins; Genetic Complementation Test; Glutamic Acid; Lysine; Models, Molecular; Mutation; Protein Binding; Protein Conformation; Recombinant Fusion Proteins; Structure-Activity Relationship; Thermodynamics

Disciplines

Life Sciences | Medicine and Health Sciences

Abstract

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.

Rights and Permissions

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

Related Resources

Link to Article in PubMed

Journal Title

Nucleic acids research

PubMed ID

11809896