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1996-02-27
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Document 0373
DOCN M9630373
TI Use of an oligoribonucleotide containing the polypurine tract sequence
as a primer by HIV reverse transcriptase.
DT 9603
AU Fuentes GM; Rodriguez-Rodriguez L; Fay PJ; Bambara RA; Department of
Microbiology & Immunology, University of Rochester,; School of Medicine
and Dentistry, New York 14642, USA.
SO J Biol Chem. 1995 Nov 24;270(47):28169-76. Unique Identifier : AIDSLINE
MED/96081850
AB A primary site for initiation of plus strand DNA synthesis in human
immunodeficiency virus (HIV) corresponds to a 19-nucleotide-long purine
rich sequence located just upstream of the U3 region, designated the
polypurine tract (PPT). The HIV reverse transcriptase (RT) uses its
RNase H activity to cut the genomic RNA after minus strand DNA
synthesis. A plus strand PPT primer is formed, extended, and then
removed. In vitro, the HIV-RT recognizes this primer specifically, using
it much more efficiently than other RNA primers. However, the PPT still
primes significantly less efficiently than DNA primers. The
19-nucleotide PPT primer is partially resistant to degradation when
compared with other oligoribonucleotides. Prior to initiation of DNA
synthesis, several nucleotides are removed by the RT from the 3' ends of
some of the PPT primers. Cleavage is enhanced in the absence of dNTPs.
We suggest that DNA synthesis suppresses primer degradation, so that
primer extension and cleavage occur in proper sequence. As a result of
3' end degradation, PPT elongation products contain 5'-RNA segments from
16 to 19 nucleotides in length. These shorter segments are also
generated from a longer transcript containing the PPT sequence,
indicating that they are not created as a result of binding of the RT to
the 5' end of the PPT oligoribonucleotide. Full-length and shorter
versions of the PPT primers are cleaved from the extended DNA by RT.
These experiments show that HIV-RT has a specificity to generate a
primer in the region of the PPT but that the ends of the primer are not
well defined.
DE Base Sequence Binding Sites DNA Primers/CHEMISTRY/*METABOLISM DNA,
Viral/BIOSYNTHESIS Human HIV/*ENZYMOLOGY Kinetics Molecular Sequence
Data Nucleic Acid Hybridization Purines RNA-Directed DNA
Polymerase/*METABOLISM Substrate Specificity Support, Non-U.S. Gov't
Support, U.S. Gov't, P.H.S. Templates JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).