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The RNA polymerase III transcription initiation factor TFIIIB participates in two steps of promoter opening
Author(s) -
Kassavetis George A.,
Letts Garth A.,
Geiduschek E.Peter
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.11.2823
Subject(s) - transcription factor ii d , transcription factor ii f , biology , rna polymerase ii , rna polymerase ii holoenzyme , general transcription factor , transcription factor ii e , transcription (linguistics) , microbiology and biotechnology , rna polymerase iii , promoter , rna polymerase , transcription factor ii a , genetics , rna , gene , gene expression , linguistics , philosophy
Evidence for post‐recruitment functions of yeast transcription factor (TF)IIIB in initiation of transcription was first provided by the properties of TFIIIB–RNA polymerase III–promoter complexes assembled with deletion mutants of its Brf and B″ subunits that are transcriptionally inactive because they fail to open the promoter. The experiments presented here show that these defects can be repaired by unpairing short (3 or 5 bp) DNA segments spanning the transcription bubble of the open promoter complex. Analysis of this suppression phenomenon indicates that TFIIIB participates in two steps of promoter opening by RNA polymerase III that are comparable to the successive steps of promoter opening by bacterial RNA polymerase holoenzyme. B″ deletions between amino acids 355 and 421 interfere with the initiating step of DNA strand separation at the upstream end of the transcription bubble. Removing an N‐terminal domain of Brf interferes with downstream propagation of the transcription bubble to and beyond the transcriptional start site.