Nucleic Acids Research, Vol 25, Issue 3 545-552, Copyright © 1997 by Oxford University Press
C Isel, C Ehresmann, G Keith, B Ehresmann and R Marquet
Retroviral reverses transcriptases (RTs) are RNA- and DNA-dependent DNA
polymerases that use a tRNA bound at the so-called primer binding site
(PBS) located near the 5'end of the genomic RNA as primer. Thus, RTs must
be able to accommodate both RNA and DNA in the primer strand. To test
whether the natural primer confers some advantages to the priming process,
we compared initiation of reverse transcription of avian and murine
retroviral RNAs, using either their natural tRNA primer, tRNATrp and
tRNAPro, respectively, or synthetic 18mer oligodeoxyribonucleotides (ODNs)
and oligoribonucleotides (ORNs) complementary to their PBS. In both
retroviral systems, the initial extension of ODNs was fast and processive.
The initial extension of ORNs, tRNATrp and tRNAPro was much slower and
distributive, giving rise to the transient accumulation of short pausing
products. Synthesis of (-) strong-stop DNA was delayed when using ORNs and
tRNAs, compared to ODNs. Even though ORNs and tRNAs were initially extended
at the same rate, the short pausing products were more rapidly extended
when using the tRNA primers. As a consequence, synthesis of (-) strong-stop
DNA was much more efficient with tRNA primers, compared to ORNs. Taken
together, these results suggest that the tRNA-primed synthesis of (-)
strong-stop DNA is a two- step process, as already observed for HIV-1. The
initiation mode corresponds to the initial non-processive nucleotide
addition and extension of the short pausing products. It is more efficient
with the natural primers than with ORNs. Initiation is followed by a more
processive and unspecific elongation mode. Elongation is observed when the
primer strand is DNA, i.e. when using the ODNs as primers or when the ORN
and tRNA primers have been extended by a sufficient number (depending on
the retroviral system) of deoxyribonucleotides.
ARTICLES
Two step synthesis of (-) strong-stop DNA by avian and murine reverse transcriptases in vitro
Unite Propre de Recherche 9002 du Centre National de la Recherche Scientifique, Institut de Biologie Moleculaire et Cellulaire, 15 rue R. Descartes, 67084 Strasbourg cedex, France.
![]()
CiteULike
Connotea
Del.icio.us What's this?
This article has been cited by other articles:
![]() |
F. Freund, F. Boulme, S. Litvak, and L. Tarrago-Litvak Initiation of HIV-2 reverse transcription: a secondary structure model of the RNA-tRNALys3 duplex Nucleic Acids Res., July 1, 2001; 29(13): 2757 - 2765. [Abstract] [Full Text] [PDF] |
||||
