A TBP complex essential for transcription from TATA-less but not TATA-containing RNA polymerase III promoters is part of the TFIIIB fraction.
The TATA box-binding protein TBP directs transcription by all three eukaryotic RNA polymerases. In mammalian cells, TBP is found in at least three different complexes: SL1, D-TFIID, and B-TFIID. While SL1 and D-TFIID are involved in RNA polymerase I and II transcription, respectively, no unique function has been assigned to the B-TFIID complex. Here we show that the TFIIIB fraction required for RNA polymerase III transcription contains two separable components, one of which is a TBP-containing complex that may correspond to B-TFIID. For transcription of TATA-less RNA polymerase III genes such as the VAI, 5S, and 7SL genes, this complex cannot be replaced by either TBP alone or the D-TFIID complex. In contrast, TBP alone is active for basal transcription from the TATA-containing U6 promoter. This indicates different requirements for recruiting TBP to TATA-less and TATA-containing RNA polymerase III promoters.
Lobo
S M
SM
Cold Spring Harbor Laboratory, New York 11724.
Tanaka
M
M
Sullivan
M L
ML
Hernandez
N
N
D001483:Base Sequence; D004258:DNA Polymerase III; D004268:DNA-Binding Proteins / Q000737:chemistry*; D012321:DNA-Directed RNA Polymerases / Q000235:genetics; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry; D011401:Promoter Regions, Genetic; D035181:TATA-Box Binding Protein; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors / Q000737:chemistry*; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D009097:Multienzyme Complexes; D035181:TATA-Box Binding Protein; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; D004258:DNA Polymerase III