Multiple roles of the tau131 subunit of yeast transcription factor IIIC (TFIIIC) in TFIIIB assembly.
Yeast transcription factor IIIC (TFIIIC) plays a key role in assembling the transcription initiation factor TFIIIB on class III genes after TFIIIC-DNA binding. The second largest subunit of TFIIIC, tau131, is thought to initiate TFIIIB assembly by interacting with Brf1/TFIIIB70. In this work, we have analyzed a TFIIIC mutant (tau131-DeltaTPR2) harboring a deletion in tau131 removing the second of its 11 tetratricopeptide repeats. Remarkably, this thermosensitive mutation was selectively suppressed in vivo by overexpression of B"/TFIIIB90, but not Brf1 or TATA-binding protein. In vitro, the mutant factor preincubated at restrictive temperature bound DNA efficiently but lost transcription factor activity. The in vitro transcription defect was abolished at high concentrations of B" but not Brf1. Copurification experiments of baculovirus-expressed proteins confirmed a direct physical interaction between tau131 and B". tau131, therefore, appears to be involved in the recruitment of both Brf1 and B".
Dumay-Odelot
Hélène
H
Service de Biochimie et de Génétique Moléculaire, CEA/Saclay, F-91191 Gif-sur-Yvette Cedex, France.
Acker
Joël
J
Arrebola
Rosalia
R
Sentenac
André
A
Marck
Christian
C
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D017930:Genes, Reporter; D006493:Heparin / Q000494:pharmacology; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D035381:TATA-Binding Protein Associated Factors; D013696:Temperature; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019474:Transcription Factors, TFIII / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000098832:Transcription Factor TFIIIC
C090956:BRF1 protein, S cerevisiae; C441028:BRF1 protein, human; D004268:DNA-Binding Proteins; D021122:Protein Subunits; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D035381:TATA-Binding Protein Associated Factors; D035361:Transcription Factor TFIIIB; D014157:Transcription Factors; D019474:Transcription Factors, TFIII; D000098832:Transcription Factor TFIIIC; D006493:Heparin