Abasic sites from cytosine as termination signals for DNA synthesis.
DNA with abasic sites has been prepared by deamination of cytosine followed by treatment of the product with uracil N-glycosylase. Termination in vitro on such templates does not occur until treatment with uracil N-glycosylase. DNA terminated one base before abasic sites created from C's has been used as a template in "second stage" reactions. With enzymes devoid or deficient in 3' greater than 5' exonuclease activity purines, particularly adenine, are preferentially added opposite the putative abasic site. 2-Aminopurine behaves more like adenine than like guanine in these experiments. Polymerase beta preferentially incorporates A opposite abasic sites produced from T, and G opposite abasic sites produced from C. We have eliminated an obvious artefact (e.g. strand switching) which might account for this observation.
D001483:Base Sequence; D003596:Cytosine / Q000502:physiology*; D045647:DNA Glycosylases; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D009699:N-Glycosyl Hydrolases / Q000378:metabolism; D013447:Sulfites; D013698:Templates, Genetic; D051981:Uracil-DNA Glycosidase
D013447:Sulfites; D003596:Cytosine; D004259:DNA-Directed DNA Polymerase; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; D051981:Uracil-DNA Glycosidase