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-Structure paper
Title | Structure of a AAA+ unfoldase in the process of unfolding substrate. |
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Journal, issue, pages | Elife, Vol. 6, Year 2017 |
Publish date | Apr 8, 2017 |
Authors | Zev A Ripstein / Rui Huang / Rafal Augustyniak / Lewis E Kay / John L Rubinstein / |
PubMed Abstract | AAA+ unfoldases are thought to unfold substrate through the central pore of their hexameric structures, but how this process occurs is not known. VAT, the homologue of eukaryotic CDC48/p97, works in ...AAA+ unfoldases are thought to unfold substrate through the central pore of their hexameric structures, but how this process occurs is not known. VAT, the homologue of eukaryotic CDC48/p97, works in conjunction with the proteasome to degrade misfolded or damaged proteins. We show that in the presence of ATP, VAT with its regulatory N-terminal domains removed unfolds other VAT complexes as substrate. We captured images of this transient process by electron cryomicroscopy (cryo-EM) to reveal the structure of the substrate-bound intermediate. Substrate binding breaks the six-fold symmetry of the complex, allowing five of the six VAT subunits to constrict into a tight helix that grips an ~80 Å stretch of unfolded protein. The structure suggests a processive hand-over-hand unfolding mechanism, where each VAT subunit releases the substrate in turn before re-engaging further along the target protein, thereby unfolding it. |
External links | Elife / PubMed:28390173 / PubMed Central |
Methods | EM (single particle) |
Resolution | 3.9 - 4.8 Å |
Structure data | |
Chemicals | ChemComp-ATP: |
Source |
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Keywords | HYDROLASE / AAA+ / ATPase / unfoldase / Complex |