8ODT

Structure of TolQR complex from E.coli

Summary for 8ODT

• Entry DOI: 10.2210/pdb8odt/pdb
• EMDB information: 16816
• Descriptor: Tol-Pal system protein TolQ, Tol-Pal system protein TolR (2 entities in total)
• Functional Keywords: tolq, tolr, tol-pal, complex, inner membrane, membrane protein
• Biological source: Escherichia coli K-12; More
• Total number of polymer chains: 7
• Total formula weight: 169319.04

Authors

Webby, M.N.,Kleanthous, C.,Press, C.E. (deposition date: 2023-03-09, release date: 2023-11-01, Last modification date: 2023-11-29)

Primary citation

Williams-Jones, D.P.,Webby, M.N.,Press, C.E.,Gradon, J.M.,Armstrong, S.R.,Szczepaniak, J.,Kleanthous, C.
Tunable force transduction through the Escherichia coli cell envelope.
Proc.Natl.Acad.Sci.USA, 120:e2306707120-e2306707120, 2023

PubMed Abstract: The outer membrane (OM) of Gram-negative bacteria is not energised and so processes requiring a driving force must connect to energy-transduction systems in the inner membrane (IM). Tol (Tol-Pal) and Ton are related, proton motive force- (PMF-) coupled assemblies that stabilise the OM and import essential nutrients, respectively. Both rely on proton-harvesting IM motor (stator) complexes, which are homologues of the flagellar stator unit Mot, to transduce force to the OM through elongated IM force transducer proteins, TolA and TonB, respectively. How PMF-driven motors in the IM generate mechanical work at the OM via force transducers is unknown. Here, using cryoelectron microscopy, we report the 4.3Å structure of the TolQR motor complex. The structure reaffirms the 5:2 stoichiometry seen in Ton and Mot and, with motor subunits related to each other by 10 to 16° rotation, supports rotary motion as the default for these complexes. We probed the mechanism of force transduction to the OM through in vivo assays of chimeric TolA/TonB proteins where sections of their structurally divergent, periplasm-spanning domains were swapped or replaced by an intrinsically disordered sequence. We find that TolA mutants exhibit a spectrum of force output, which is reflected in their respective abilities to both stabilise the OM and import cytotoxic colicins across the OM. Our studies demonstrate that structural rigidity of force transducer proteins, rather than any particular structural form, drives the efficient conversion of PMF-driven rotary motions of 5:2 motor complexes into physiologically relevant force at the OM.

PubMed: 37972066
DOI: 10.1073/pnas.2306707120

Experimental method

ELECTRON MICROSCOPY (4.2 Å)