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-Structure paper
タイトル | Tunable force transduction through the cell envelope. |
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ジャーナル・号・ページ | Proc Natl Acad Sci U S A, Vol. 120, Issue 47, Page e2306707120, Year 2023 |
掲載日 | 2023年11月21日 |
著者 | Daniel P Williams-Jones / Melissa N Webby / Cara E Press / Jan M Gradon / Sophie R Armstrong / Joanna Szczepaniak / Colin Kleanthous / |
PubMed 要旨 | 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 ...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. |
リンク | Proc Natl Acad Sci U S A / PubMed:37972066 / PubMed Central |
手法 | EM (単粒子) |
解像度 | 4.2 Å |
構造データ | EMDB-16816, PDB-8odt: |
由来 |
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キーワード | MEMBRANE PROTEIN / TolQ / TolR / Tol-Pal / complex / inner membrane |