A novel RNA polymerase II-containing complex potentiates Tat-enhanced HIV-1 transcription.
The HIV-1-encoded Tat protein controls transcription elongation by increasing processivity of RNA polymerase II (Pol II). Here, we have identified a Tat stimulatory activity (Tat-SF) as a novel RNA Pol II-containing complex. Remarkably, Tat-SF contains the previously identified Tat cofactors Tat-SF1, P-TEFb and hSPT5/Tat-CT1, in addition to RNA Pol II and other unidentified polypeptides, but none of the SRB/MED proteins or other factors found associated with the previously described RNA Pol II holoenzyme complex. Tat-SF supports basal, Sp1-activated and Tat-activated transcription in a reconstituted system, and a Tat-SF-derived fraction lacking RNA Pol II can complement non-responsive RNA Pol II complexes for Tat-enhanced HIV-1 transcription, indicating that Tat-SF contains factors that are critical for Tat function. Both Tat-SF and RNA Pol II holoenzyme are present in HeLa nuclear extracts and each can be recruited to the HIV-1 promoter. Our results indicate that Tat-SF is a Tat cofactor-containing RNA Pol II complex whose recruitment to the promoter provides elongation factors important for Tat-enhanced HIV-1 transcription following TAR RNA synthesis.
Laboratory of Biochemistry and Molecular Biology, The Rockefeller University, New York, NY 10021, USA.
C A
CA
Parada
R G
RG
Roeder
D002467:Cell Nucleus / Q000201:enzymology / Q000378:metabolism; D002853:Chromatography, Liquid; D015967:Gene Expression Regulation, Viral; D015696:Gene Products, tat / Q000378:metabolism*; D005816:Genetic Complementation Test; D015497:HIV-1 / Q000235:genetics*; D006367:HeLa Cells; D020035:Holoenzymes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D012319:RNA Polymerase II / Q000302:isolation & purification / Q000378:metabolism*; D016329:Sp1 Transcription Factor / Q000502:physiology; D015534:Trans-Activators / Q000302:isolation & purification / Q000378:metabolism; D019473:Transcription Factors, TFII / Q000302:isolation & purification / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics*; D054322:tat Gene Products, Human Immunodeficiency Virus
D015696:Gene Products, tat; C101819:HTATSF1 protein, human; D020035:Holoenzymes; D009097:Multienzyme Complexes; D016329:Sp1 Transcription Factor; D015534:Trans-Activators; D019473:Transcription Factors, TFII; D054322:tat Gene Products, Human Immunodeficiency Virus; D012319:RNA Polymerase II