Open AccessDomains of the Brf Component of RNA Polymerase III Transcription Factor IIIB (TFIIIB): Functions in Assembly of TFIIIB-DNA Complexes and Recruitment of RNA Polymerase to the Promoter
Author(s) -
George A. Kassavetis,
Carolyne Bardeleben,
Ashok Kumar,
Enrique Ramírez,
E. Peter Geiduschek
Publication year - 1997
Publication title -
molecular and cellular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.14
H-Index - 327
eISSN - 1067-8824
pISSN - 0270-7306
DOI - 10.1128/mcb.17.9.5299
Subject(s) - transcription factor ii a , biology , transcription (linguistics) , rna polymerase iii , transcription factor ii b , tata binding protein , microbiology and biotechnology , tata box binding protein , transcription preinitiation complex , genetics , transcription factor , general transcription factor , dna , polymerase , dna binding protein , promoter , gene , rna dependent rna polymerase , gene expression , linguistics , philosophy
Saccharomyces cerevisiae transcription factor IIIB (TFIIIB) is composed of three subunits: the TATA-binding protein, the TFIIB-related protein Brf, and B". TFIIIB, which is brought to RNA polymerase III-transcribed genes indirectly through interaction with DNA-bound TFIIIC or directly through DNA recognition by the TATA-binding protein, in turn recruits RNA polymerase III to the promoter. N-terminally deleted derivatives of Brf have been examined for their ability to interact with DNA-bound TFIIIC and with the other components of TFIIIB and for participation in transcription. Brf(165-596), lacking 164 N-proximal TFIIB-homologous amino acids, is competent to participate in the assembly of TFIIIB-DNA complexes and in TFIIIC-independent transcription. Even deletion of the entire TFIIB-homologous half of the protein, as in Brf(317-596) and Brf(352-596), allows some interaction with DNA-bound TBP and with the B" component of TFIIIB to be retained. The function of Brf(165-596) in transcription has also been examined in the context of B" with small internal deletions. The ability of Brf with this sizable N-terminal segment deleted to function in TFIIIC-independent transcription requires segments of B" that are individually indispensable although required on an either/or basis, in the context of complete Brf. These findings suggest a functional complementarity and reciprocity between the Brf and B" components of TFIIIB.