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MutM, a protein that prevents G.C----T.A transversions, is formamidopyrimidine-DNA glycosylase

M L Michaels1, L Pham, C Cruz

  • 1Molecular Biology Institute, University of California, Los Angeles 90024.

Nucleic Acids Research
|July 11, 1991
PubMed

Insights

MutM is identified as formamidopyrimidine-DNA glycosylase (Fapy-DNA glycosylase), an enzyme crucial for DNA repair. This discovery explains the specific G.C to T.A mutations observed in mutM strains, linking DNA repair to mutagenesis.

Area of Science:

  • Molecular Biology
  • Genetics
  • DNA Repair Mechanisms

Background:

  • The mutM strain exhibits specific G.C to T.A transversions, indicating a defect in DNA repair.
  • Formamidopyrimidine-DNA glycosylase (Fapy-DNA glycosylase) is known to repair oxidative DNA damage.

Purpose of the Study:

  • To identify the gene product responsible for the mutM mutator phenotype.
  • To elucidate the role of Fapy-DNA glycosylase in DNA repair and mutagenesis.

Main Methods:

  • Cloning and sequencing of chromosomal DNA flanking an insertional mutation in mutM.
  • Complementation analysis using an overproducing clone of Fapy-DNA glycosylase.
  • Correlation of in vivo mutational data with the known functions of Fapy-DNA glycosylase.

Main Results:

  • The insert inactivating mutM was located between the promoter and the structural gene for Fapy-DNA glycosylase.
  • An overproducing Fapy-DNA glycosylase clone complemented the mutM strain.
  • The mutator phenotype of mutM correlates with the repair of 8-oxo-7,8-dihydro-2'-deoxyguanine (8-OxodG) by Fapy-DNA glycosylase.

Conclusions:

  • MutM is functionally identical to Fapy-DNA glycosylase.
  • Fapy-DNA glycosylase plays a critical role in preventing G.C to T.A transversions, likely through the repair of 8-OxodG lesions.

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