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 ...
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-γ-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.
Organizational Affiliation:
Center for Quantitative Biology, Peking University, Beijing, 100871, China. youdong_mao@dfci.harvard.edu.,Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA. youdong_mao@dfci.harvard.edu.,State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Institute of Condensed Matter and Material Physics, School of Physics, Peking University, Beijing, 100871, China.,Department of Systems Biology, Harvard Medical School, Boston, MA, 02115, USA. ying_lu@hms.harvard.edu.,State Key Laboratory for Artificial Microstructures and Mesoscopic Physics, Institute of Condensed Matter and Material Physics, School of Physics, Peking University, Beijing, 100871, China. youdong_mao@dfci.harvard.edu.,Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA. youdong_mao@dfci.harvard.edu.,Department of Cancer Immunology and Virology, Dana-Farber Cancer Institute, Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA, 02115, USA.,Center for Quantitative Biology, Peking University, Beijing, 100871, China.,Intel Parallel Computing Center for Structural Biology, Dana-Farber Cancer Institute, Boston, MA, 02215, USA.
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