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Publication Abstract from PubMed

The 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^[2]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.