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J. Virol., 08 1997, 6113-6127, Vol 71, No. 8
C Van Lint, CA Amella, S Emiliani, M John, T Jie and E Verdin
When transcriptionally active, the human immunodeficiency virus (HIV)
promoter contains a nucleosome-free region encompassing both the
promoter/enhancer region and a large region (255 nucleotides [nt])
downstream of the transcription start site. We have previously identified
new binding sites for transcription factors downstream of the transcription
start site (nt 465 to 720): three AP-1 sites (I, II, and III), an AP3-like
motif (AP3-L), a downstream binding factor (DBF) site, and juxtaposed Sp1
sites. Here, we show that the DBF site is an interferon-responsive factor
(IRF) binding site and that the AP3-L motif binds the T-cell-specific
factor NF-AT. Mutations that abolish the binding of each factor to its
cognate site are introduced in an infectious HIV-1 molecular clone to study
their effect on HIV-1 transcription and replication. Individual mutation of
the DBF or AP3-L site as well as the double mutation AP-1(III)/AP3-L did
not affect HIV- 1 replication compared to that of the wild-type virus. In
contrast, proviruses carrying mutations in the Sp1 sites were totally
defective in terms of replication. Virus production occurred with slightly
delayed kinetics for viruses containing combined mutations in the AP-
1(III), AP3-L, and DBF sites and in the AP3-L and DBF-sites, whereas
viruses mutated in the AP-1(I,II,III) and AP3-L sites and in the AP-
1(I,II,III), AP3-L, and DBF sites exhibited a severely defective
replicative phenotype. No RNA-packaging defect could be measured for any of
the mutant viruses as determined by quantification of their HIV genomic
RNA. Measurement of the transcriptional activity of the HIV-1 promoter
after transient transfection of the HIV-1 provirus DNA or of long terminal
repeat-luciferase constructs showed a positive correlation between the
transcriptional and the replication defects for most mutants.
Copyright © 1997, American Society for Microbiology
Transcription factor binding sites downstream of the human immunodeficiency virus type 1 transcription start site are important for virus infectivity
The Picower Institute for Medical Research, Manhasset, New York 11030, USA.
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