National Institutes of Health/National Institute of Mental Health (NIH/NIMH)
R01-GM144542
米国
National Institutes of Health/National Institute of General Medical Sciences (NIH/NIGMS)
R35-GM141517
米国
National Science Foundation (NSF, United States)
2046778
米国
引用
ジャーナル: Nat Commun / 年: 2024 タイトル: A proteolytic AAA+ machine poised to unfold protein substrates. 著者: Alireza Ghanbarpour / Robert T Sauer / Joseph H Davis / 要旨: AAA+ proteolytic machines unfold proteins before degrading them. Here, we present cryoEM structures of ClpXP-substrate complexes that reveal a postulated but heretofore unseen intermediate in ...AAA+ proteolytic machines unfold proteins before degrading them. Here, we present cryoEM structures of ClpXP-substrate complexes that reveal a postulated but heretofore unseen intermediate in substrate unfolding/degradation. A ClpX hexamer draws natively folded substrates tightly against its axial channel via interactions with a fused C-terminal degron tail and ClpX-RKH loops that flexibly conform to the globular substrate. The specific ClpX-substrate contacts observed vary depending on the substrate degron and affinity tags, helping to explain ClpXP's ability to unfold/degrade a wide array of different cellular substrates. Some ClpX contacts with native substrates are enabled by upward movement of the seam subunit in the AAA+ spiral, a motion coupled to a rearrangement of contacts between the ClpX unfoldase and ClpP peptidase. Our structures additionally highlight ClpX's ability to translocate a diverse array of substrate topologies, including the co-translocation of two polypeptide chains.