Cryo-EM structures of the autoinhibited <em>E. coli</em> ATP synthase in three rotational states
- The Victor Chang Cardiac Research Institute, Australia
- Nanyang Technological University, Singapore
- University of Oxford, United Kingdom
Abstract
A molecular model that provides a framework for interpreting the wealth of functional information obtained on the <em>E. coli</em> F-ATP synthase has been generated using cryo-electron microscopy. Three different states that relate to rotation of the enzyme were observed, with the central stalk's ε subunit in an extended autoinhibitory conformation in all three states. The Fo motor comprises of seven transmembrane helices and a decameric c-ring and invaginations on either side of the membrane indicate the entry and exit channels for protons. The proton translocating subunit contains near parallel helices inclined by ~30º to the membrane, a feature now synonymous with rotary ATPases. For the first time in this rotary ATPase subtype, the peripheral stalk is resolved over its entire length of the complex, revealing the F1 attachment points and a coiled-coil that bifurcates towards the membrane with its helices separating to embrace subunit a from two sides.
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Author details
Alastair G Stewart
Funding
National Health and Medical Research Council (1004620)
- Daniela Stock
National Health and Medical Research Council (1109961)
- Daniela Stock
National Health and Medical Research Council (1090408)
- Alastair G Stewart
National Health and Medical Research Council (1022143)
- Daniela Stock
National Health and Medical Research Council (1047004)
- Daniela Stock
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2016, Sobti et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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Cryo-EM structures of the autoinhibited <em>E. coli</em> ATP synthase in three rotational states
eLife 5:e21598.
https://doi.org/10.7554/eLife.21598
Further reading
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- Biochemistry and Chemical Biology
- Structural Biology and Molecular Biophysics
The two identical motor domains (heads) of dimeric kinesin-1 move in a hand-over-hand process along a microtubule, coordinating their ATPase cycles such that each ATP hydrolysis is tightly coupled to a step and enabling the motor to take many steps without dissociating. The neck linker, a structural element that connects the two heads, has been shown to be essential for head–head coordination; however, which kinetic step(s) in the chemomechanical cycle is ‘gated’ by the neck linker remains unresolved. Here, we employed pre-steady-state kinetics and single-molecule assays to investigate how the neck-linker conformation affects kinesin’s motility cycle. We show that the backward-pointing configuration of the neck linker in the front kinesin head confers higher affinity for microtubule, but does not change ATP binding and dissociation rates. In contrast, the forward-pointing configuration of the neck linker in the rear kinesin head decreases the ATP dissociation rate but has little effect on microtubule dissociation. In combination, these conformation-specific effects of the neck linker favor ATP hydrolysis and dissociation of the rear head prior to microtubule detachment of the front head, thereby providing a kinetic explanation for the coordinated walking mechanism of dimeric kinesin.
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- Structural Biology and Molecular Biophysics
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