ausblenden:
Schlagwörter:
-
Zusammenfassung:
The eukaryotic RNA polymerases Pol I, II, and III use
different promoters to transcribe different classes of
genes. Promoter usage relies on initiation factors,
including TFIIF and TFIIE, in the case of Pol II. Here,
we show that the Pol I-specific subunits A49 and
A34.5 form a subcomplex that binds DNA and is
related to TFIIF and TFIIE. The N-terminal regions
of A49 and A34.5 form a dimerization module
that stimulates polymerase-intrinsic RNA cleavage
and has a fold that resembles the TFIIF core. The
C-terminal region of A49 forms a ‘‘tandem winged
helix’’ (tWH) domain that bindsDNA with a preference
for the upstream promoter nontemplate strand and is
predicted in TFIIE. Similar domains are predicted in
Pol III-specific subunits. Thus, Pol I/III subunits that
have no counterparts in Pol II are evolutionarily
related to Pol II initiation factors and may have
evolved to mediate promoter specificity and transcription
processivity.
