期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 109, 期 37, 页码 14870-14875出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1213333109
关键词
protein degradation; electron microscopy; deubiquitylating enzyme
资金
- European Union [HEALTH-F4-2008-201648]
- Deutsche Forschungsgemeinschaft [SFB 594, GRK 1721]
- Human Frontier Science Project
The 26S proteasome operates at the executive end of the ubiquitin-proteasome pathway. Here, we present a cryo-EM structure of the Saccharomyces cerevisiae 26S proteasome at a resolution of 7.4 angstrom or 6.7 angstrom ( Fourier-Shell Correlation of 0.5 or 0.3, respectively). We used this map in conjunction with molecular dynamics-based flexible fitting to build a near-atomic resolution model of the holocomplex. The quality of the map allowed us to assign alpha-helices, the predominant secondary structure element of the regulatory particle subunits, throughout the entire map. We were able to determine the architecture of the Rpn8/Rpn11 heterodimer, which had hitherto remained elusive. The MPN domain of Rpn11 is positioned directly above the AAA-ATPase N-ring suggesting that Rpn11 deu-biquitylates substrates immediately following commitment and prior to their unfolding by the AAA-ATPase module. The MPN domain of Rpn11 dimerizes with that of Rpn8 and the C-termini of both subunits form long helices, which are integral parts of a coiled-coil module. Together with the C-terminal helices of the six PCI-domain subunits they form a very large coiled-coil bundle, which appears to serve as a flexible anchoring device for all the lid subunits.
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