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TBP domain symmetry in basal and activated archaeal transcription
Author(s) -
Ouhammouch Mohamed,
Hausner Winfried,
Geiduschek E. Peter
Publication year - 2009
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/j.1365-2958.2008.06512.x
Subject(s) - biology , transcription preinitiation complex , transcription (linguistics) , transcription factor ii a , general transcription factor , transcription factor ii b , microbiology and biotechnology , genetics , gene , promoter , rna polymerase , rna , gene expression , linguistics , philosophy
Summary The TATA box binding protein (TBP) is the platform for assembly of archaeal and eukaryotic transcription preinitiation complexes. Ancestral gene duplication and fusion events have produced the saddle‐shaped TBP molecule, with its two direct‐repeat subdomains and pseudo‐two‐fold symmetry. Collectively, eukaryotic TBPs have diverged from their present‐day archaeal counterparts, which remain highly symmetrical. The similarity of the N‐ and C‐halves of archaeal TBPs is especially pronounced in the Methanococcales and Thermoplasmatales, including complete conservation of their N‐ and C‐terminal stirrups; along with helix H′1, the C‐terminal stirrup of TBP forms the main interface with TFB/TFIIB. Here, we show that, in stark contrast to its eukaryotic counterparts, multiple substitutions in the C‐terminal stirrup of Methanocaldococcus jannaschii (Mja) TBP do not completely abrogate basal transcription. Using DNA affinity cleavage, we show that, by assembling TFB through its conserved N‐terminal stirrup, Mja TBP is in effect ambidextrous with regard to basal transcription. In contrast, substitutions in either its N‐ or the C‐terminal stirrup abrogate activated transcription in response to the Lrp‐family transcriptional activator Ptr2.