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1996-03-09
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Document 0162
DOCN M9650162
TI Helix structure and ends of RNA/DNA hybrids direct the cleavage
specificity of HIV-1 reverse transcriptase RNase H.
DT 9605
AU Palaniappan C; Fuentes GM; Rodriguez-Rodriguez L; Fay PJ; Bambara RA;
Department of Biochemistry, University of Rochester, New York; 14642,
USA.
SO J Biol Chem. 1996 Jan 26;271(4):2063-70. Unique Identifier : AIDSLINE
MED/96147182
AB RNA/DNA hybrids in human immunodeficiency virus (HIV) replication are
cleaved by HIV-1 reverse transcriptase (RT) H in locations determined by
hybrid structure. Minus strand DNA synthesis is accompanied by cleavage
of template viral RNA directed by RT positioned at the growing 3' DNA
end. Some RNA remains as oligomers annealed to the new DNA strand and is
cut by RTs positioned at the 5' RNA ends. We constructed substrates to
the test the hypothesis that internal helix structure, rather than
strand end structure, drives the RT to position at 3' DNA and 5' RNA
ends. On substrates with an RNA primer recessed on a DNA template, the
5' end of the RNA had a dominant role in the determination of RNase H
cleavage positions. If the 5' end region of the RNA could not anneal,
cleavage would not occur. Nevertheless, we obtained evidence that helix
structure promotes the binding of RT to the end of the helical region
closest to the 5' RNA/3' DNA end. When a DNA primer recessed on an RNA
template had a 3' unannealed region, cleavage occurred, with RT
positioned solely by helical structure at the 5' RNA/3' DNA end of the
annealed region of the hybrid. Using substrates having RNA primers
annealed to circular DNA templates, we showed that cleavage can be
independent of the presence of a DNA 3'end and is directed by the 5' RNA
end. Overall, the results suggest that the RT initially binds an
internal region of the hybrid and then is driven in the direction to
encounter a 3' DNA or 5' RNA end, where it is positioned for catalysts
by the strand end. The requirement for two modes of RNA cleavage in
viral replication and the unexpected requirement for the 5' RNA end
structure are discussed.
DE Base Sequence DNA Primers/CHEMISTRY DNA, Single-Stranded/METABOLISM
DNA, Viral/METABOLISM Kinetics Molecular Sequence Data Nucleic Acid
Hybridization Recombinant Proteins Ribonuclease H, Calf
Thymus/CHEMISTRY/*METABOLISM RNA-Directed DNA
Polymerase/CHEMISTRY/*METABOLISM RNA, Viral/METABOLISM
Structure-Activity Relationship Substrate Specificity 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).