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Nucleotide-driven Triple-state Remodeling of the AAA-ATPase Channel in the Activated Human 26S Proteasome
Structural highlights
FunctionPSA6_HUMAN The proteasome is a multicatalytic proteinase complex which is characterized by its ability to cleave peptides with Arg, Phe, Tyr, Leu, and Glu adjacent to the leaving group at neutral or slightly basic pH. The proteasome has an ATP-dependent proteolytic activity. Publication Abstract from PubMedThe proteasome is a sophisticated ATP-dependent molecular machine responsible for protein degradation in all known eukaryotic cells. It remains elusive how conformational changes of the AAA-ATPase unfoldase in the regulatory particle (RP) control the gating of the substrate-translocation channel leading to the proteolytic chamber of the core particle (CP). Here we report three alternative states of the ATP-gamma-S-bound human proteasome, in which the CP gates are asymmetrically open, visualized by cryo-EM at near-atomic resolutions. At least four nucleotides are bound to the AAA-ATPase ring in these open-gate states. Variation in nucleotide binding gives rise to an axial movement of the pore loops narrowing the substrate-translation channel, which exhibit remarkable structural transitions between the spiral-staircase and saddle-shaped-circle topologies. Gate opening in the CP is thus regulated by nucleotide-driven conformational changes of the AAA-ATPase unfoldase. These findings demonstrate an elegant mechanism of allosteric coordination among sub-machines within the human proteasome holoenzyme. Structural mechanism for nucleotide-driven remodeling of the AAA-ATPase unfoldase in the activated human 26S proteasome.,Zhu Y, Wang WL, Yu D, Ouyang Q, Lu Y, Mao Y Nat Commun. 2018 Apr 10;9(1):1360. doi: 10.1038/s41467-018-03785-w. PMID:29636472[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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