Base-pairing properties of O6-methylguanine in template DNA during in vitro DNA replication.
J Biol Chem
; 259(13): 8095-100, 1984 Jul 10.
Article
em En
| MEDLINE
| ID: mdl-6376499
ABSTRACT
The kinetics of incorporation of deoxynucleotide precursors directed by the promutagenic base, O6-methylguanine (m6Gua), was analyzed during in vitro replication of m6Gua-containing synthetic polydeoxynucleotides by T4 and T5 phage DNA polymerases and Escherichia coli DNA polymerase I. When poly(dT,m6dG) and poly(dC,m6dG) with covalently attached primers were replicated, O6-methylguanine paired with either thymine or cytosine but with a much higher preference for thymine. dCTP and dTTP acted as competitive inhibitors of each other during DNA synthesis. O6-Methylguanine also directed incorporation of dAMP by T5 DNA polymerase. This dAMP incorporation was not inhibited by dTTP. Contrary to theoretical predictions that the m6dG X dT pair should be comparable to the dA X dT pair, the presence of m6dG in the template inhibited DNA synthesis. Based on Kappm values, E. coli DNA polymerase I showed a much higher preference for dTMP incorporation over dCMP opposite m6dG 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 m6Gua-containing templates was more than that observed with templates without the alkylated base.
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Base de dados:
MEDLINE
Assunto principal:
Fagos T
/
DNA Polimerase I
/
DNA Polimerase Dirigida por DNA
/
Replicação do DNA
/
Escherichia coli
/
Guanina
Limite:
Animals
Idioma:
En
Revista:
J Biol Chem
Ano de publicação:
1984
Tipo de documento:
Article