Mutagenic properties of O/sup 6/-methylguanine in DNA in vivo and in vitro

Conference · Sat Jan 01 04:00:00 EST 1983

OSTI ID:5347568

Snow, E T; Foote, R S; Dodson, L A; Masker, W; Mitra, S

Among the many basic alkylated sites produced in DNA by simple alkylating mutagens, O/sup 6/-alkylguanine is believed to be the major promutagenic lesion. Using O/sup 6/-methyl dGTP as a substrate during in vitro synthesis of biologically active T7 DNA we have shown that the incorporation of the alkylated nucleotide leads to increased reversion of an amber mutation in the phage DNA. We have shown that O/sup 6/-methylguanine has a strong preference for pairing with thymine over cytosine during in vitro replication of synthetic DNA templates with T4 and T5 phage DNA polymerases and E. coli DNA polymerase I. The degree of preference depends not only on the DNA polymerase used but possibly on other factors as well, including the divalent metal ion cofactors. The alkylated base in the template DNA also inhibits chain elongation of the product strand. While O/sup 6/-methyl dGTP can act as a substrate for DNA polymerases, as an analog of dATP, the alkylated nucleotide is incorporated only infrequently and inhibits overall DNA synthesis at the same time. A much higher turnover of the alkylated nucleotide than that of the normal nucleotides suggests that O/sup 6/-methylguanine is not recognized as a normal base by the DNA polymerases in spite of the fact that it is predicted to form a stable base pair with thymine.

• Research Organization: Oak Ridge National Lab., TN (USA); Tennessee Univ., Oak Ridge (USA). Graduate School of Biomedical Sciences
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5347568
• Report Number(s): CONF-831258-2; ON: DE84004576
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ADDUCTS
ALKYLATION
AMINES
AROMATICS
AZAARENES
BACTERIOPHAGES
BIOCHEMICAL REACTION KINETICS
BIOLOGICAL FUNCTIONS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
DNA
DNA ADDUCTS
DNA POLYMERASES
ENZYMES
FUNCTIONS
GUANINE
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
KINETICS
MICROORGANISMS
MUTATIONS
NUCLEIC ACIDS
NUCLEOTIDES
NUCLEOTIDYLTRANSFERASES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARASITES
PHOSPHORUS-GROUP TRANSFERASES
POLYMERASES
PURINES
REACTION KINETICS
RECOVERY
REPAIR
TRANSFERASES
VIRUSES