A human chromosome 12-associated 83-kilodalton cellular protein specifically binds to the loop region of human immunodeficiency virus type 1 trans-activation response element RNA.
trans activation of human immunodeficiency virus type 1 (HIV-1) involves the viral trans-activator protein (Tat) and a cellular factor(s) encoded on human chromosome 12 (HuChr12) that targets the trans-activation response element (TAR) in the viral long terminal repeat. Because nascent TAR RNA is predicted to form a secondary structure that specifically binds cellular proteins, we investigated the composition of the TAR RNA-protein complex for HuChr12-specific proteins. UV cross-linking of TAR RNA-nuclear protein complexes formed in vitro identified an 83-kDa protein in human cells and in a human-hamster hybrid cell containing only HuChr12. The 83-kDa TAR RNA-binding protein was absent in the parental hamster cells. TAR RNA mutations that inhibited binding of the 83-kDa protein in vitro also inhibited HuChr12-dependent Tat trans activation. These TAR mutations changed the native sequence or secondary structure of the TAR loop. The TAR RNA binding activity of the 83-kDa protein also correlated with a HuChr12-dependent increase in steady-state HIV-1 RNA expression during Tat trans activation. Our results suggest that either a species-specific 83-kDa TAR RNA loop-binding protein is directly encoded on HuChr12 or a HuChr12 protein(s) induces the expression of an 83-kDa TAR-binding protein in nonprimate cells.
Hart
C E
CE
Retrovirus Disease Branch, Centers for Disease Control and Prevention, Atlanta, Georgia 30333, USA.
Saltrelli
M J
MJ
Galphin
J C
JC
Schochetman
G
G
D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D015500:Chloramphenicol O-Acetyltransferase / Q000096:biosynthesis; D002881:Chromosomes, Human, Pair 12; D006224:Cricetinae; D015696:Gene Products, tat / Q000378:metabolism*; D016325:HIV Long Terminal Repeat; D015497:HIV-1 / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009687:Nuclear Proteins / Q000302:isolation & purification / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D015533:Transcriptional Activation; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; D009687:Nuclear Proteins; D012367:RNA, Viral; D016601:RNA-Binding Proteins; D011994:Recombinant Proteins; D054322:tat Gene Products, Human Immunodeficiency Virus; D015500:Chloramphenicol O-Acetyltransferase