Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
Kinetics of deoxyribonucleotide insertion and extension at abasic template lesions in different sequence contexts using HIV-1 reverse transcriptase.
J Biol Chem. 1993 Nov 5;268(31):23567-72. Unique Identifier : AIDSLINE MED/94043158 Cai H; Bloom LB; Eritja R; Goodman MF; Department of Biological Sciences, University of Southern; California, Los Angeles 90089-1340.
Abstract:
Deoxyribonucleotide insertion efficiencies were measured opposite site-directed abasic template lesions using human immunodeficiency virus 1 reverse transcriptase (HIV-1RT), and the efficiencies to continue primer synthesis beyond the lesion, by addition of the next correct deoxynucleotide, were measured as a function of sequence context. Insertion of purines was favored over pyrimidines, A > G > T approximately C. Primer extension past the lesion occurred by two distinct mechanisms, either by direct or by misalignment extension. An A-rule appeared to hold for the case of direct extension, where the abasic template moiety is intrahelical, aligned opposite the primer 3'-terminus. In misalignment extension, the primer terminus is realigned from a site directly opposite the lesion to a new position opposite a neighboring template base 5' to the lesion. Direct extension efficiencies were measured in 16 different configurations, by varying 4 bases at the primer 3'-termini and 4 at the 5'-side (downstream) of the lesion. The predominant order of direct extension was A > G > T approximately C, similar to that observed for insertion. Reduced primer extension rates were not caused by a reduction in HIV-1 RT-DNA binding. Primers terminating in C showed inefficient direct extension, but were readily extended via misaligned configurations. The ratios of direct-to-misalignment extension efficiencies were 27:1, 2.5:1, and 1:25 for A, G, and C opposite the lesion, respectively. For the case of primers terminating in T, misalignment extension was not observed. A striking result was that while primers were extended past an abasic lesion by HIV-1 RT in both direct and misalignment modes, avian myeloblastosis virus RT failed to catalyze significant extension by either mode.
Keywords: Animal Drosophila melanogaster/ENZYMOLOGY DNA Damage DNA Polymerase II/METABOLISM DNA Repair Kinetics Myeloblastosis Virus, Avian/ENZYMOLOGY RNA-Directed DNA Polymerase/*METABOLISM Substrate Specificity Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Templates JOURNAL ARTICLE 940228
M9420025
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Important note: Information in this article was accurate in 1994. The state of the art may have changed since the publication date.
