Eg. Bridges et al., INFLUENCE OF TEMPLATE PRIMARY STRUCTURE ON 3'-AZIDO-3'-DEOXYTHYMIDINETRIPHOSPHATE INCORPORATION INTO DNA, Antiviral research, 21(2), 1993, pp. 93-102
In the present study, templates containing a specific segment of the G
gamma-globin gene were constructed and incorporation of 3'-azido-3'-de
oxythymidine 5'-triphosphate (AZT-TP) or 2',3'-dideoxythymidine 5'-tri
phosphate (ddTTP) into these templates was compared to that observed i
n M13 bacteriophage DNA. Investigations on the intrinsic fidelity of T
7 DNA polymerase in reactions with AZT-TP and without deoxythymidine 5
'-triphosphate, resulted in DNA synthesis beyond the first T site, sug
gesting that other normal deoxynucleotides misincorporated at these T
sites. Modified T7 DNA polymerase incorporated AZT-TP into T sites of
elongating DNA strands. Chain termination at noncomplementary sites wa
s also observed with AZT-TP when a genomic DNA template was used and i
nterestingly, this phenomenon was not detected in the presence of a M1
3 DNA template. These DNA template-dependent effects were not detected
with either ddTTP, 2',3'-dideoxycytidine 5'-triphosphate, or 2',3'-di
dehydro-2',3'-dideoxythymidine 5'-triphosphate (D4T-TP). A variation i
n the extent of chain termination at T sites was observed with D4T-TP
suggesting that each 2',3'-dideoxynucleoside may exhibit unique chain
termination patterns along with the template sequence.