The 26S Proteasome Utilizes a Kinetic Gateway to Prioritize Substrate Degradation.

Autor:	Bard JAM; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA., Bashore C; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA., Dong KC; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA., Martin A; Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California at Berkeley, Berkeley, CA 94720, USA; Howard Hughes Medical Institute, University of California at Berkeley, Berkeley, CA 94720, USA. Electronic address: a.martin@berkeley.edu.
Jazyk:	angličtina
Zdroj:	Cell [Cell] 2019 Apr 04; Vol. 177 (2), pp. 286-298.e15. Date of Electronic Publication: 2019 Mar 28.
DOI:	10.1016/j.cell.2019.02.031
Abstrakt:	The 26S proteasome is the principal macromolecular machine responsible for protein degradation in eukaryotes. However, little is known about the detailed kinetics and coordination of the underlying substrate-processing steps of the proteasome, and their correlation with observed conformational states. Here, we used reconstituted 26S proteasomes with unnatural amino-acid-attached fluorophores in a series of FRET- and anisotropy-based assays to probe substrate-proteasome interactions, the individual steps of the processing pathway, and the conformational state of the proteasome itself. We develop a complete kinetic picture of proteasomal degradation, which reveals that the engagement steps prior to substrate commitment are fast relative to subsequent deubiquitination, translocation, and unfolding. Furthermore, we find that non-ideal substrates are rapidly rejected by the proteasome, which thus employs a kinetic proofreading mechanism to ensure degradation fidelity and substrate prioritization. (Copyright © 2019 Elsevier Inc. All rights reserved.)
Databáze:	MEDLINE
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