C. Harrington et Fw. Perrino, THE EFFECTS OF CYTOSINE-ARABINOSIDE OIL RNA-PRIMED DNA-SYNTHESIS BY DNA-POLYMERASE ALPHA-PRIMASE, The Journal of biological chemistry, 270(44), 1995, pp. 26664-26669
Oligonucleotides containing a specific initiation site for polymerase
alpha-primase (pol alpha-primase) were used to measure the effects of
cytosine arabinoside triphosphate and cytosine arabinoside monophospha
te (araCMP) in DNA on RNA-primed DNA synthesis. Primase inserts araCMP
at the 3' terminus of a full-length RNA primer with a 400-fold prefer
ence over GRIP. The araCMP is elongated efficiently by pol alpha in th
e primase-coupled reaction. Extension from RNA 3'-araCMP is 50-fold le
ss efficient than from CMP, and extension from DNA 3'-araCMP is 1600-f
old less efficient than from dCMP. Using araCMP-containing templates,
primer synthesis is reduced 2-3 fold, and RNA-primed DNA synthesis is
reduced 2-8-fold. The efficiency of polymerization past a template ara
CMP by pol alpha is reduced 180-fold during insertion of dGMP opposite
araCMP and 35-fold during extension from the araCMP:dGMP 3' terminus.
These results show that the pol alpha-primase efficiently incorporate
s araCMP as the border nucleotide between RNA and DNA and suggest that
the inhibitory effects of araC most likely result from slowed elongat
ion of pol a: and less so from inhibition of primer synthesis by prima
se.