Base-pairing properties of O/sup 6/-methylguanine during DNA replication in vitro

Technical Report · Wed Dec 01 04:00:00 EST 1982

OSTI ID:5411433

Snow, E T

O/sup 6/-methylguanine (m/sup 6/G), because of its ability to ''mispair'' with thymine during replication, is an important premutagenic lesion produced in DNA by simple alkylating carcinogens. The kinetics of incorporation of nucleotide precursors opposite m/sup 6/G were analyzed during replication of synthetic deoxynucleotide polymers containing m/sup 6/dG as the only modified base by T5 phage-induced DNA polymerase. Incorporation of dTMP opposite m/sup 6/dG is preferred nearly ten-fold over incorporation of dCMP opposite m/sup 6/dG. dTTP and dCTP are linear competitive inhibitors for incorporation opposite m/sup 6/dG. dAMP is also incorporated opposite m/sup 6/dG but does not compete with dTMP incorporation. It is proposed that dA base-pairs with m/sup 6/dG in the dA/sub anti/:m/sup 6/dG/sub syn/ configuration. Different DNA polymerases vary in their ability to discriminate between dT:m/sup 6/dG and dC:m/sup 6/dG base-pairs. The relative number of mutations produced during replication of DNA containing m/sup 6/dG will depend on the DNA polymerase, DNA precursor pool concentrations, DNA sequence, and possibly other factors. Alkylated nucleotides in the DNA precursor pool may also contribute to mutagenesis induced by simple alkylating agents. m/sup 6/dGMP can be incorporated into DNA by several different DNA polymerases using both natural and synthetic template-primers. The rate of incorporation of m/sup 6/dGMP is significantly less than the rate of incorporation of normal dNTP substrates. Incorporation of m/sup 6/dGMP from the nucleotide pool will depend on the DNA polymerase, deoxynucleotide pool concentrations, and other possible factors. Mutagenesis due to m/sup 6/dGMP incorporation during DNA replication in vivo will be insignificant compared mutagenesis due to the m/sup 6/dG produced in DNA directly by simple alkylating carcinogens. 117 refs., 29 figs., 7 tabs.

• Research Organization: Oak Ridge Associated Universities, Inc., TN (USA)
• DOE Contract Number: AC05-76OR00033
• OSTI ID: 5411433
• Report Number(s): DOE/OR/00033-T103; ON: DE85015018
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALKYLATING AGENTS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CARCINOGENESIS
CHEMISTRY
CHROMATOGRAPHY
DAYS LIVING RADIOISOTOPES
DNA MISMATCH
DNA POLYMERASES
DNA REPAIR
ENZYMES
ISOTOPE APPLICATIONS
ISOTOPES
KINETICS
LABELLED COMPOUNDS
LIGHT NUCLEI
LIQUID COLUMN CHROMATOGRAPHY
MUTATION FREQUENCY
NUCLEI
NUCLEOTIDYLTRANSFERASES
ODD-ODD NUCLEI
PATHOGENESIS
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
POLYMERASES
RADIOISOTOPES
REACTION KINETICS
RECOVERY
REPAIR
SEPARATION PROCESSES
TRACER TECHNIQUES
TRANSFERASES
TRITIUM COMPOUNDS