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Lookup NU author(s): Dr Agata Starosta
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Under stress conditions, such as nutrient starvation, deacylated tRNAs bound within the ribosomal A-site are recognized by the stringent factor RelA, which converts ATP and GTP/GDP to (p)ppGpp. The signaling molecules (p) ppGpp globally rewire the cellular transcriptional program and general metabolism, leading to stress adaptation. Despite the additional importance of the stringent response for regulation of bacterial virulence, antibiotic resistance and persistence, structural insight into how the ribosome and deacylated-tRNA stimulate RelA-mediated (p)ppGpp has been lacking. Here, we present a cryo-EM structure of RelA in complex with the Escherichia coli 70S ribosome with an average resolution of 3.7 angstrom and local resolution of 4 to > 10 angstrom for RelA. The structure reveals that RelA adopts a unique 'open' conformation, where the C-terminal domain (CTD) is intertwined around an A/T-like tRNA within the intersubunit cavity of the ribosome and the N-terminal domain (NTD) extends into the solvent. We propose that the open conformation of RelA on the ribosome relieves the autoinhibitory effect of the CTD on the NTD, thus leading to stimulation of (p)ppGpp synthesis by RelA.
Author(s): Arenz S, Abdelshahid M, Sohmen D, Payoe R, Starosta AL, Berninghausen O, Hauryliuk V, Beckmann R, Wilson DN
Publication type: Article
Publication status: Published
Journal: Nucleic Acids Research
Year: 2016
Volume: 44
Issue: 13
Pages: 6471-6481
Print publication date: 27/07/2016
Online publication date: 25/05/2016
Acceptance date: 12/05/2016
Date deposited: 10/11/2016
ISSN (print): 0305-1048
ISSN (electronic): 1362-4962
Publisher: Oxford University Press
URL: http://dx.doi.org/10.1093/nar/gkw470
DOI: 10.1093/nar/gkw470
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