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Tunable force transduction through the Escherichia coli cell envelope

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 ess...

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Autores principales: Williams-Jones, Daniel P., Webby, Melissa N., Press, Cara E., Gradon, Jan M., Armstrong, Sophie R., Szczepaniak, Joanna, Kleanthous, Colin
Formato: Online Artículo Texto
Lenguaje:English
Publicado: National Academy of Sciences 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10666116/
https://www.ncbi.nlm.nih.gov/pubmed/37972066
http://dx.doi.org/10.1073/pnas.2306707120
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author Williams-Jones, Daniel P.
Webby, Melissa N.
Press, Cara E.
Gradon, Jan M.
Armstrong, Sophie R.
Szczepaniak, Joanna
Kleanthous, Colin
author_facet Williams-Jones, Daniel P.
Webby, Melissa N.
Press, Cara E.
Gradon, Jan M.
Armstrong, Sophie R.
Szczepaniak, Joanna
Kleanthous, Colin
author_sort Williams-Jones, Daniel P.
collection PubMed
description 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 Escherichia coli 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.
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spelling pubmed-106661162023-11-16 Tunable force transduction through the Escherichia coli cell envelope Williams-Jones, Daniel P. Webby, Melissa N. Press, Cara E. Gradon, Jan M. Armstrong, Sophie R. Szczepaniak, Joanna Kleanthous, Colin Proc Natl Acad Sci U S A Biological Sciences 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 Escherichia coli 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. National Academy of Sciences 2023-11-16 2023-11-21 /pmc/articles/PMC10666116/ /pubmed/37972066 http://dx.doi.org/10.1073/pnas.2306707120 Text en Copyright © 2023 the Author(s). Published by PNAS. https://creativecommons.org/licenses/by/4.0/This open access article is distributed under Creative Commons Attribution License 4.0 (CC BY) (https://creativecommons.org/licenses/by/4.0/) .
spellingShingle Biological Sciences
Williams-Jones, Daniel P.
Webby, Melissa N.
Press, Cara E.
Gradon, Jan M.
Armstrong, Sophie R.
Szczepaniak, Joanna
Kleanthous, Colin
Tunable force transduction through the Escherichia coli cell envelope
title Tunable force transduction through the Escherichia coli cell envelope
title_full Tunable force transduction through the Escherichia coli cell envelope
title_fullStr Tunable force transduction through the Escherichia coli cell envelope
title_full_unstemmed Tunable force transduction through the Escherichia coli cell envelope
title_short Tunable force transduction through the Escherichia coli cell envelope
title_sort tunable force transduction through the escherichia coli cell envelope
topic Biological Sciences
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10666116/
https://www.ncbi.nlm.nih.gov/pubmed/37972066
http://dx.doi.org/10.1073/pnas.2306707120
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