Identification of a Group of Cellular Cofactors That Stimulate the Binding of RNA Polymerase II and TRP-185 to Human Immunodeficiency Virus 1 TAR RNA (∗)

• Published in: The Journal of biological chemistry 1996-02, Vol.271 (8), p.4201-4208
• Main Authors: Wu-Baer, Foon, Lane, William S., Gaynor, Richard B.
• Format: Article
• Language: English
• Subjects: AIDS/HIV; Amino Acid Sequence; Cell Nucleus - metabolism; Chromatography, Gel; Chromatography, Ion Exchange; Cloning, Molecular; Gene Expression Regulation, Viral; HeLa Cells; HIV Long Terminal Repeat; HIV-1 - metabolism; human immunodeficiency virus 1; Humans; Molecular Sequence Data; Nuclear Proteins - biosynthesis; Nuclear Proteins - isolation & purification; Nuclear Proteins - metabolism; Recombinant Proteins - biosynthesis; Recombinant Proteins - metabolism; RNA Polymerase II - metabolism; RNA, Viral - biosynthesis; RNA, Viral - metabolism; RNA-Binding Proteins - biosynthesis; RNA-Binding Proteins - isolation & purification; RNA-Binding Proteins - metabolism; Sequence Homology, Amino Acid; Transcription Factors - biosynthesis; Transcription Factors - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.271.8.4201

A double-stranded RNA structure transcribed from the HIV-1 long terminal repeat known as TAR is critical for increasing gene expression in response to the transactivator protein Tat. Two cellular factors, RNA polymerase II and TRP-185, bind specifically to TAR RNA, but require the presence of cellular proteins known as cofactors which by themselves are unable to bind to TAR RNA. In an attempt to determine the mechanism by which these cofactors stimulate binding to TAR RNA, we purified these factors from HeLa nuclear extract and amino acid microsequence analysis performed. Three proteins were identified in the cofactor fraction including two previously described proteins, elongation factor 1α (EF-1α) and the polypyrimidine tract-binding protein (PTB), and a novel protein designated the stimulator of TAR RNA-binding proteins (SRB). SRB has a high degree of homology with a variety of cellular proteins known as chaperonins. Recombinant EF-1α, PTB, and SRB produced from vaccinia expression vectors stimulated the binding of RNA polymerase II and TRP-185 to TAR RNA in gel retardation analysis. These studies define a group of cellular factors that function in concert to stimulate the binding of TRP-185 and RNA polymerase II to HIV-1 TAR RNA.