An α helix to β barrel domain switch transforms the transcription factor RfaH into a translation factor

Titelangaben

Burmann, Björn M. ; Knauer, Stefan H. ; Sevostyanova, Anastasia ; Schweimer, Kristian ; Mooney, Rachel A. ; Landick, Robert ; Artsimovitch, Irina ; Rösch, Paul:
An α helix to β barrel domain switch transforms the transcription factor RfaH into a translation factor.
In: Cell. Bd. 150 (2012) Heft 2 . - S. 291-303.
ISSN 1097-4172
DOI: https://doi.org/10.1016/j.cell.2012.05.042

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Abstract

NusG homologs regulate transcription and coupled processes in all living organisms. The Escherichia coli (E. coli) two-domain paralogs NusG and RfaH have conformationally identical N-terminal domains (NTDs) but dramatically different carboxy-terminal domains (CTDs), a β barrel in NusG and an α hairpin in RfaH. Both NTDs interact with elongating RNA polymerase (RNAP) to reduce pausing. In NusG, NTD and CTD are completely independent, and NusG-CTD interacts with termination factor Rho or ribosomal protein S10. In contrast, RfaH-CTD makes extensive contacts with RfaH-NTD to mask an RNAP-binding site therein. Upon RfaH interaction with its DNA target, the operon polarity suppressor (ops) DNA, RfaH-CTD is released, allowing RfaH-NTD to bind to RNAP. Here, we show that the released RfaH-CTD completely refolds from an all-α to an all-β conformation identical to that of NusG-CTD. As a consequence, RfaH-CTD binding to S10 is enabled and translation of RfaH-controlled operons is strongly potentiated.