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MPI für Biochemie  

Molecular Structural Biology
Wolfgang Baumeister

The Proteasome

 

Members

 

Alumni:

Dr. Stephan Nickell

Dr. Eri Sakata

Dr. Susanne Witt

Dr. Sarah Breuer


Overview

12-04-02-web-klein

 

The 26S proteasome is a large molecular machine with a central role in intracellular protein degradation in eukaryotes.

The 2.5 MDa complex, which is built from two copies each of more than 30 different subunits, is labile and prone to dissociation into subcomplexes. Hence it is difficult if not impossible, to obtain structurally homogeneous preparations and, as a consequence, it is very cumbersome to obtain large numbers of images of the holocomplex. Therefore we have used an automated procedure for the acquisition of large data sets of cryoelectron micrographs. The application of this procedure to the 26S proteasome from Drosophila has allowed us to determine the three-dimensional structure of the complex to a resolution of 2.9 nm and the prospects for further improvements are good.

 

In the recent years, we have investigated the translocation of substrate molecules into the 20S proteasome by means of force spectroscopy, the structure of the host-guest complex and the reaction mechanism of proteolysis with the help of cryoelectron microscopy, mutant studies and X-ray crystallography.

Subunit arrangement in the 26S Proteasome Regulatory Particle

This movie shows the arrangement of proteasomal subunits in the 19S regulatory particle of the 26S holocomplex (Lasker et al., Sakata et al., Pathare et al.). Whereas this movie gives a good impression of the spatial arrangement of proteins within this macromolecular complex, it does not serve the purpose of explaining its assembly or disassembly pathways. Used for segmentation was the Schizosaccharomyces pombe cryoEM density at a nominal resolution of 8.4 Å at FSC = 0.5 (EMDB code 2035).

 

26S_assembly_MPI_watermarked_2012

 

Publications

  1. Lasker K, Förster F, Bohn S, Walzthoeni T, Villa E, Unverdorben P, Beck F, Aebersold R, Sali A, Baumeister W, Molecular architecture of the 26S proteasome holocomplex determined by an integrative approach. Proc. Natl. Acad. Sci. USA. 109:1380-7 (2012)
  2. Sakata E, Bohn S, Mihalache O, Kiss P, Beck F, Nagy I, Nickell S, Tanaka K, Saeki Y, Förster F, Baumeister W, Localization of the proteasomal ubiquitin receptors Rpn10 and Rpn13 by electron cryomicroscopy. Proc. Natl. Acad. Sci. USA. 109:1479-84 (2012)
  3. Pathare GR, Nagy I, Bohn S, Unverdorben P, Hubert A, Körner R, Nickell S, Lasker K, Sali A, Tamura T, Nishioka T, Förster F, Baumeister W, Bracher A, The proteasomal subunit Rpn6 is a molecular clamp holding the core and regulatory subcomplexes together. Proc. Natl. Acad. Sci. USA. 109(1):149-54 (2012)
  4. Bohn S, Beck F, Sakata E, Walzthoeni T, Beck M, Aebersold R, Förster F, Baumeister W, Nickell S, Structure of the 26S proteasome from Schizosaccharomyces pombe at sub-nanometer resolution. Proc. Natl. Acad. Sci. USA 107:20992-7 (2010)
  5. Classen M, Breuer S, Baumeister W, Guckenberger R, Witt S. Force spectroscopy of substrate molecules en route to the proteasome´s active sites. Biophys. J. 100:489-497 (2011)
  6. Ruschak AM, Tomasz, LR, Breuer S, Witt S, Kay, LE. The proteasome antechamber maintains substrates in an unfolded state. Nature 467:868-873 (2010)
  7. Nickell S, Beck F, Scheres SH, Korinek A, Förster F, Lasker K, Mihalache O, Sun N, Nagy I, Sali A, Plitzko JM, Carazo JM, Mann M, Baumeister W. Insights into the molecular architecture of the 26S proteasome. Proc Natl Acad Sci U S A. 2009 Jul 21;106(29):11943-7. Epub 2009 Jul 6.
  8. Nickell S, Mihalache O, Beck F, Hegerl R, Korinek A, Baumeister W. Structural analysis of the 26S proteasome by cryoelectron tomography. Biochem Biophys Res Commun., 2007. 353(1): p. 115-20.
  9. Nickell S, Beck F, Korinek A, Mihalache O, Baumeister W, Plitzko JM. Automated cryoelectron microscopy of "single particles" applied to the 26S proteasome.FEBS Lett., 2007. 581(15): p. 2751-6.
  10. Sharon M, Witt S, Felderer K, Rockel B, Baumeister W, Robinson CV. 20S proteasome keeps substrates in store for continual degradation. J. Biol. Chem. 281:9569-9575 (2006)