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M9550116.TXT
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1995-03-04
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Document 0116
DOCN M9550116
TI A novel LBP-1-mediated restriction of HIV-1 transcription at the level
of elongation in vitro.
DT 9505
AU Parada CA; Yoon JB; Roeder RG; Laboratory of Biochemistry and Molecular
Biology, Rockefeller; University, New York, New York 10021.
SO J Biol Chem. 1995 Feb 3;270(5):2274-83. Unique Identifier : AIDSLINE
MED/95138199
AB The cellular factor, LBP-1, can repress HIV-1 transcription by
preventing the binding of TFIID to the promoter. Here we have analyzed
the effect of recombinant LBP-1 on HIV-1 transcription in vitro by using
a pulse-chase assay. LBP-1 had no effect on initiation from a preformed
preinitiation complex and elongation to position +13 (pulse). However,
addition of LBP-1 after RNA polymerase was stalled at +13 strongly
inhibited further elongation (chase) by reducing RNA polymerase
processivity. Severe mutations of the high affinity LBP-1 binding sites
between 4 and +21 did not relieve the LBP-1-dependent block. However,
LBP-1 could bind independently to upstream low affinity sites (-80 to
-4), suggesting that these sites mediate the effect of LBP-1 on
elongation. These results demonstrate a novel function of LBP-1,
restricting HIV-1 transcription at the level of elongation. In addition,
Tat was found to suppress the antiprocessivity effect of LBP-1 on HIV-1
transcription in nuclear extracts. These findings strongly suggest that
LBP-1 may provide a natural mechanism for restricting the elongation of
HIV-1 transcripts and that this may be a target for the action of Tat in
enhancing transcription.
DE Base Sequence DNA-Binding Proteins/*PHYSIOLOGY Gene Expression
Regulation, Viral Gene Products, tat/METABOLISM Hela Cells Human
HIV-1/*GENETICS In Vitro Molecular Sequence Data Mutagenesis,
Site-Directed Promoter Regions (Genetics) Recombinant Proteins
Repressor Proteins/*PHYSIOLOGY RNA Polymerases/*METABOLISM RNA,
Viral/*BIOSYNTHESIS Structure-Activity Relationship Support, Non-U.S.
Gov't Support, U.S. Gov't, P.H.S. Transcription, Genetic TATA Box
JOURNAL ARTICLE
SOURCE: National Library of Medicine. NOTICE: This material may be
protected by Copyright Law (Title 17, U.S.Code).