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EMBO Rep. 2008 Dec;9(12):1237-43. doi: 10.1038/embor.2008.190. Epub 2008 Oct 17.

Blm10 binds to pre-activated proteasome core particles with open gate conformation.

Author information

  • 1Institute of Biochemistry, Charité-Universitätsmedizin Berlin, Monbijoustrasse 2, 10117 Berlin, Germany.

Erratum in

  • EMBO Rep. 2009 Jan;10(1):101.

Abstract

Blm10 is bound to the yeast proteasome core particle, a crucial protease of eukaryotic cells [corrected]. Two gates, at both ends of the CP, control the access of protein substrates to the catalytic cavity of the CP. Normally, substrate access is auto-inhibited by a closed gate conformation unless regulatory complexes are bound to the CP and translocate protein substrates in an ATP-dependent manner. Here, we provide evidence that Blm10 recognizes pre-activated open gate CPs, which are assumed to exist in an equilibrium with inactive closed gate CP. Consequently, single-capped Blm10-CP shows peptide hydrolysis activity. Under conditions of disturbed CP assembly, as well as in open gate mutants, pre-activated CP or constitutively active CP, respectively, prevail. Then, Blm10 sequesters disordered and open gate CP by forming double-capped Blm10(2)-CP in which peptide hydrolysis activity is repressed. We conclude that Blm10 distinguishes between gate conformations and regulates the activation of CP.

PMID:
18927584
[PubMed - indexed for MEDLINE]
PMCID:
PMC2603454
Free PMC Article

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