The single-stranded DNA binding protein, Pur-alpha, binds HIV-1 TAR RNA and activates HIV-1 transcription.
Previous studies indicate that the bulge and loop domains of TAR, the HIV-1 RNA regulatory element, bind viral and cellular factors that are critical for efficient transcription of the HIV-1 genome. In this report, we demonstrate that the cellular protein, Pur-alpha, a previously characterized sequence specific, single-stranded DNA binding protein, binds to HIV-1 TAR RNA in a specific manner as demonstrated by competition analysis. Pur-alpha binds to the greatest extent to wild-type TAR RNA, and it appears the primary sequence, as well as the secondary structure and its overall stability contribute to this binding. Results from gel shift analysis using mutant Pur-alpha proteins indicate that amino acids 55-85, which contain the first of three basic aromatic repeats, are important for its binding to TAR RNA. Overexpression of Pur-alpha in a glial cell line increased transcription of HIV-1 LTR by a TAR dependent mechanism. The potential contribution by Pur-alpha to HIV-1 expression in relation to basal transcription by cellular factors is discussed.
Chepenik
L G
LG
Center for NeuroVirology, NeuroOncology, Allegheny University of the Health Sciences, Philadelphia, PA 19102, USA.
Tretiakova
A P
AP
Krachmarov
C P
CP
Johnson
E M
EM
Khalili
K
K
D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein; D004277:DNA, Single-Stranded / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D015967:Gene Expression Regulation, Viral / Q000235:genetics; D016325:HIV Long Terminal Repeat / Q000235:genetics*; D015497:HIV-1 / Q000235:genetics*; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D012367:RNA, Viral / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000235:genetics; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics; D015533:Transcriptional Activation / Q000235:genetics*; D014162:Transfection / Q000235:genetics
D017362:Cyclic AMP Response Element-Binding Protein; D004277:DNA, Single-Stranded; D004268:DNA-Binding Proteins; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D014157:Transcription Factors