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

Journal Article · Tue Jul 10 04:00:00 EDT 1984 · J. Biol. Chem.; (United States)

OSTI ID:5751460

Snow, E T; Foote, R S; Mitra, S

The kinetics of incorporation of deoxynucleotide precursors directed by the promutagenic base, O/sup 6/-methylguanine (m/sup 6/Gua), was analyzed in vitro replication of m/sup 6/Gua-containing synthetic polydeoxynucleotides by T4 and T5 phage DNA polymerases and Escherichia coli DNA polymerase I. When poly(dT,m/sup 6/dG) and poly(dC,m/sup 6/dG) with covalently attached primers were replicated, O/sup 6/-methylguanine paired with either thymine or cystosine but with a much higher preference for thymine, dCTP, and dTTP acted as competitive inhibitors of each other during DNA synthesis. O/sup 6/-methylguanine also directed incorporation of dAMP by T5 DNA polymerase. This dAMP incorporation was not inhibited by dTTP. Contrary to theoretical predictions that the m/sup 6/dG.dT pair should be comparable to the dA.dT pair, the presence of m/sup 6/dG in the template inhibited DNA synthesis. Based on K/sub mm//sup app/ values, E. coli DNA polymerase I showed a much higher preference for dTMP incorporation over dCMP opposite m/sup 6/dG in the template than T4 and T5 DNA polymerases. At the same time, there was a higher turnover of dCTP than of dTTP by the E. coli enzyme. However, in all cases, the turnover of deoxynucleotides during replication of m/sup 6/Gua-containing templates was more than that observed with templates without the alkylated base.

• Research Organization: Oak Ridge National Lab., TN
• DOE Contract Number: W-7405-ENG-26
• OSTI ID: 5751460
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 259:13; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

560302* -- Chemicals Metabolism & Toxicology-- Microorganisms-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKYLATING AGENTS
BACTERIA
BACTERIOPHAGES
BIOCHEMICAL REACTION KINETICS
DNA MISMATCH
DNA POLYMERASES
DNA REPLICATION
ENZYME ACTIVITY
ENZYMES
ESCHERICHIA COLI
IN VITRO
INHIBITION
KINETICS
MICROORGANISMS
MUTAGENESIS
NUCLEIC ACID REPLICATION
NUCLEOTIDYLTRANSFERASES
PARASITES
PHOSPHORUS-GROUP TRANSFERASES
POLYMERASES
REACTION KINETICS
TRANSFERASES
VIRUSES