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The beta Subunit Gate Loop Is Required for RNA Polymerase Modification by RfaH and NusG
Tekijät: Anastasia Sevostyanova, Georgiy A Belogurov, Rachel A Mooney, Robert Landick, Irina Artsimovitch
Julkaisuvuosi: 2011
Journal: Molecular Cell
Tietokannassa oleva lehden nimi: Mol Cell
Numero sarjassa: 2
Vuosikerta: 43
Numero: 2
Aloitussivu: 253
Lopetussivu: 262
Sivujen määrä: 10
ISSN: 1097-2765
DOI: https://doi.org/10.1016/j.molcel.2011.05.026
Tiivistelmä
In all organisms, RNA polymerase (RNAP) relies on accessory factors to complete synthesis of long RNAs. These factors increase RNAP processivity by reducing pausing and termination, but their molecular mechanisms remain incompletely understood. We identify the beta gate loop as an RNAP element required for antipausing activity of a bacterial virulence factor RfaH, a member of the universally conserved NusG family. Interactions with the gate loop are necessary for suppression of pausing and termination by RfaH, but are dispensable for RfaH binding to RNAP mediated by the beta' clamp helices. We hypothesize that upon binding to the clamp helices and the gate loop RfaH bridges the gap across the DNA channel, stabilizing RNAP contacts with nucleic acid and disfavoring isomerization into a paused state. We show that contacts with the gate loop are also required for antipausing by NusG and propose that most NusG homologs use similar mechanisms to increase RNAP processivity.
In all organisms, RNA polymerase (RNAP) relies on accessory factors to complete synthesis of long RNAs. These factors increase RNAP processivity by reducing pausing and termination, but their molecular mechanisms remain incompletely understood. We identify the beta gate loop as an RNAP element required for antipausing activity of a bacterial virulence factor RfaH, a member of the universally conserved NusG family. Interactions with the gate loop are necessary for suppression of pausing and termination by RfaH, but are dispensable for RfaH binding to RNAP mediated by the beta' clamp helices. We hypothesize that upon binding to the clamp helices and the gate loop RfaH bridges the gap across the DNA channel, stabilizing RNAP contacts with nucleic acid and disfavoring isomerization into a paused state. We show that contacts with the gate loop are also required for antipausing by NusG and propose that most NusG homologs use similar mechanisms to increase RNAP processivity.
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