Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates

© 2020, eLife Sciences Publications Ltd. All rights reserved. When ribosomes fail to complete normal translation, all cells have mechanisms to ensure degradation of the resulting partial proteins to safeguard proteome integrity. In E. coli and other eubacteria, the tmRNA system rescues stalled ribos...

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Main Authors: Fei, Xue, Bell, Tristan A, Barkow, Sarah R, Baker, Tania A, Sauer, Robert T
Format: Article
Language:English
Published: eLife Sciences Publications, Ltd 2021
Online Access:https://hdl.handle.net/1721.1/135281
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author Fei, Xue
Bell, Tristan A
Barkow, Sarah R
Baker, Tania A
Sauer, Robert T
author_facet Fei, Xue
Bell, Tristan A
Barkow, Sarah R
Baker, Tania A
Sauer, Robert T
author_sort Fei, Xue
collection MIT
description © 2020, eLife Sciences Publications Ltd. All rights reserved. When ribosomes fail to complete normal translation, all cells have mechanisms to ensure degradation of the resulting partial proteins to safeguard proteome integrity. In E. coli and other eubacteria, the tmRNA system rescues stalled ribosomes and adds an ssrA tag or degron to the C-terminus of the incomplete protein, which directs degradation by the AAA+ ClpXP protease. Here, we present cryo-EM structures of ClpXP bound to the ssrA degron. C-terminal residues of the ssrA degron initially bind in the top of an otherwise closed ClpX axial channel and subsequently move deeper into an open channel. For short-degron protein substrates, we show that unfolding can occur directly from the initial closed-channel complex. For longer-degron substrates, our studies illuminate how ClpXP transitions from specific recognition into a nonspecific unfolding and translocation machine. Many AAA+ proteases and protein-remodeling motors are likely to employ similar multistep recognition and engagement strategies.
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spelling mit-1721.1/1352812021-10-28T05:03:37Z Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates Fei, Xue Bell, Tristan A Barkow, Sarah R Baker, Tania A Sauer, Robert T © 2020, eLife Sciences Publications Ltd. All rights reserved. When ribosomes fail to complete normal translation, all cells have mechanisms to ensure degradation of the resulting partial proteins to safeguard proteome integrity. In E. coli and other eubacteria, the tmRNA system rescues stalled ribosomes and adds an ssrA tag or degron to the C-terminus of the incomplete protein, which directs degradation by the AAA+ ClpXP protease. Here, we present cryo-EM structures of ClpXP bound to the ssrA degron. C-terminal residues of the ssrA degron initially bind in the top of an otherwise closed ClpX axial channel and subsequently move deeper into an open channel. For short-degron protein substrates, we show that unfolding can occur directly from the initial closed-channel complex. For longer-degron substrates, our studies illuminate how ClpXP transitions from specific recognition into a nonspecific unfolding and translocation machine. Many AAA+ proteases and protein-remodeling motors are likely to employ similar multistep recognition and engagement strategies. 2021-10-27T20:22:46Z 2021-10-27T20:22:46Z 2020 2021-07-14T12:48:18Z Article http://purl.org/eprint/type/JournalArticle https://hdl.handle.net/1721.1/135281 en 10.7554/ELIFE.61496 eLife Creative Commons Attribution 4.0 International license https://creativecommons.org/licenses/by/4.0/ application/pdf eLife Sciences Publications, Ltd eLife
spellingShingle Fei, Xue
Bell, Tristan A
Barkow, Sarah R
Baker, Tania A
Sauer, Robert T
Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates
title Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates
title_full Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates
title_fullStr Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates
title_full_unstemmed Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates
title_short Structural basis of ClpXP recognition and unfolding of ssrA-tagged substrates
title_sort structural basis of clpxp recognition and unfolding of ssra tagged substrates
url https://hdl.handle.net/1721.1/135281
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