The fission yeast TFIIB-related factor limits RNA polymerase III to a TATA-dependent pathway of TBP recruitment.
The RNA polymerase (pol) III-transcribed (e.g. tRNA and 5S rRNA) genes of traditionally studied organisms rely on gene-internal promoters that precisely position the initiation factor, TFIIIB, on the upstream promoter-less DNA. This is accomplished by the ability of the TFIIIB subunit, TFIIB-related factor (Brf1), to make stable protein-protein interactions with TATA-binding protein (TBP) and place it on the promoter-less upstream DNA. Unlike traditional model organisms, Schizosaccharomyces pombe tRNA and 5S rRNA genes contain upstream TATA promoters that are required to program functional pol III initiation complexes. In this study we demonstrate that S.pombe (Sp)Brf does not form stable interactions with TBP in the absence of DNA using approaches that do reveal stable association of TBP and S.cerevisiae (Sc)Brf1. Gel mobility analyses demonstrate that a TBP-TATA DNA complex can recruit SpBrf to a Pol III promoter. Consistent with this, overproduction of SpBrf in S.pombe increases the expression of a TATA-dependent, but not a TATA-less, suppressor tRNA gene. Since previous whole genome analysis also revealed TATA elements upstream of tRNA genes in Arabidopsis, this pathway may be more widespread than appreciated previously.
Huang
Ying
Y
Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2753, USA.
McGillicuddy
Edward
E
Weindel
Michael
M
Dong
Steven
S
Maraia
Richard J
RJ
D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D011485:Protein Binding; D012320:RNA Polymerase III / Q000378:metabolism*; D012362:RNA, Transfer, Ser / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D012568:Schizosaccharomyces / Q000235:genetics* / Q000378:metabolism; D016385:TATA Box / Q000235:genetics*; D035181:TATA-Box Binding Protein / Q000378:metabolism*; D035361:Transcription Factor TFIIIB / Q000235:genetics / Q000378:metabolism*
C090956:BRF1 protein, S cerevisiae; D004271:DNA, Fungal; D012362:RNA, Transfer, Ser; D029701:Saccharomyces cerevisiae Proteins; D035181:TATA-Box Binding Protein; D035361:Transcription Factor TFIIIB; D012320:RNA Polymerase III