Isolation and structural characterization of a cDNA clone encoding the human DNA repair protein for O sup 6 -alkylguanine

Journal Article · Mon Jan 01 00:00:00 EST 1990 · Proceedings of the National Academy of Sciences of the United States of America; (USA)

DOI:https://doi.org/10.1073/pnas.87.2.686· OSTI ID:6719542

Tano, K; Shiota, S; Collier, J; Foote, R S; Mitra, S ^[1]

---

1. Oak Ridge National Lab., TN (USA)

O{sup 6}-Methylguanine-DNA methyltransferase a unique DNA repair protein present in most organisms, removes the carcinogenic and mutagenic adduct O{sup 6}-alkylguanine from DNA by stoichiometrically accepting the alkyl group on a cysteine residue in a suicide reaction. The mammalian protein is highly regulated in both somatic and germ-like cells. In addition, the toxicity of certain alkylating drugs in tumor and normal cells is inversely related to the levels of this protein. The cDNA of the human gene, henceforth named MGMT, has been cloned in an expression vector on the basis of its rescue of a methyltransferase-deficient (ada{sup {minus}}) Escherichia coli host. A 22-kDa active methyltransferase encoded entirely by the cDNA contains an amino acid sequence of 61 residues that bears 60-65% similarity with segments of E. coli methyltransferase which encompass the alkyl-acceptor residues. The human cDNA has no sequence similarity with the ada and ogt genes, due in part to differences in codon usage, and shows no detectable homology with E. coli genomic DNA. However, it hybridizes with distinct restriction fragments of human, mouse, and rat DNAs. The lack of methyltransferase observed in many human cell lines is due to the absence of the MGNT gene or to lack of synthesis and/or stability of its 0.95-kilobase poly(A){sup +} RNA transcript.

• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6719542
• Journal Information: Proceedings of the National Academy of Sciences of the United States of America; (USA), Vol. 87:2; ISSN 0027-8424
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
ALKYLATING AGENTS
GENETIC EFFECTS
METHYL TRANSFERASES
GENE REGULATION
RECOMBINANT DNA
DNA-CLONING
AMINO ACID SEQUENCE
BIOLOGICAL EVOLUTION
DNA ADDUCTS
DNA HYBRIDIZATION
DNA REPAIR
ESCHERICHIA COLI
HELA CELLS
MAN
MICE
PHOSPHORUS 32
RATS
ADDUCTS
ANIMALS
BACTERIA
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CLONING
DAYS LIVING RADIOISOTOPES
DNA
ENZYMES
HYBRIDIZATION
ISOTOPES
LIGHT NUCLEI
MAMMALS
MICROORGANISMS
MOLECULAR STRUCTURE
NUCLEI
NUCLEIC ACIDS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
PRIMATES
RADIOISOTOPES
RECOVERY
REPAIR
RODENTS
TRANSFERASES
VERTEBRATES
550201* - Biochemistry- Tracer Techniques