Premium
Effects of DNA strand breaks on transcription by RNA polymerase III: insights into the role of TFIIIB and the polarity of promoter opening
Author(s) -
Kassavetis George A.,
Grove Anne,
Geiduschek E.Peter
Publication year - 2002
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/cdf533
Subject(s) - rna polymerase iii , general transcription factor , transcription (linguistics) , promoter , genetics , rna polymerase ii , transcription factor ii d , transcription bubble , biology , dna , microbiology and biotechnology , polymerase , gene , rna dependent rna polymerase , gene expression , linguistics , philosophy
Certain deletion mutants of the Brf1 and Bdp1 subunits of transcription factor (TF) IIIB retain the ability to recruit RNA polymerase (pol) III to its promoters, but fail to support promoter opening: deletions within an internal Bdp1 segment interfere with initiation of DNA strand separation, and an N‐terminal Brf1 deletion blocks propagation of promoter opening past the transcriptional start site. The ability of DNA strand breaks to restore pol III transcription activity to these defective TFIIIB assemblies has been analyzed using U6 snRNA gene constructs. Breaks in a 21 bp segment spanning the transcriptional start rescue transcription in DNA strand‐specific and subunit/mutation‐specific patterns. A cluster of Bdp1 internal deletions also reverses the inactivation of transcription with wild‐type TFIIIB generated by certain transcribed (template) strand breaks near the transcriptional start site. A structure‐based model and topological considerations interpret these observations, explain how Bdp1 and Brf1 help to enforce the general upstream→ downstream polarity of promoter opening and specify requirements for polarity reversal.