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NLM AIDSLINE

Binding of host-cell factors to DNA sequences in the long terminal repeat of human T-cell leukemia virus type I: implications for viral gene expression.




 

Proc Natl Acad Sci U S A. 1988 Mar;85(5):1457-61. Unique Identifier :

Efficient expression of human T-cell leukemia virus type I (HTLV-I) genes requires both host and viral proteins and is dependent on DNA sequences in the proviral long terminal repeats (LTRs). We have used DNase I-protection assays (footprinting) to construct a map of protein-DNA interactions over a 250-nucleotide region of the LTR upstream of the start site for viral RNA synthesis. We find that a host factor (host expression factor 1, or HEF-1) binds to the imperfect 21-nucleotide repeats that have previously been implicated in HTLV-I gene expression. HEF-1 binding activity is present in preparations from both lymphoid and nonlymphoid cell lines. However, the boundaries of the protected regions and the presence of a flanking DNase-hypersensitive site vary with cell type. Several regions of binding are detected in addition to the HEF-1 sites, including a complex group of sites 40-90 nucleotides upstream of the RNA start site. A comparison of HTLV-I-transformed T lymphocytes that do and do not express the viral trans-activating protein p40xI shows that none of the observed features of the DNase I footprint pattern correlate directly with the presence of this protein in the extract. These results suggest (i) that the primary recognition of promoter elements in the HTLV-I LTR involves specific interactions with host-cell proteins and (ii) that p40xI influences the activity of one or more of these proteins, rather than interacting directly with the DNA.

Binding Sites Cell Line Deoxyribonuclease I/DIAGNOSTIC USE DNA-Binding Proteins/*PHYSIOLOGY DNA, Viral/*METABOLISM Gene Expression Regulation Human HTLV-BLV Viruses/*GENETICS *Repetitive Sequences, Nucleic Acid Support, Non-U.S. Gov't Support, U.S. Gov't, P.H.S. Transcription, Genetic JOURNAL ARTICLE



 




Information in this article was accurate in June 30, 1988. The state of the art may have changed since the publication date. This material is designed to support, not replace, the relationship that exists between you and your doctor. Always discuss treatment options with a doctor who specializes in treating HIV.