7DR7

bovine 20S immunoproteasome

Summary for 7DR7

• Entry DOI: 10.2210/pdb7dr7/pdb
• EMDB information: 30825
• Descriptor: Proteasome subunit alpha type-7, Proteasome subunit beta type-1, Proteasome subunit beta type-4, ... (14 entities in total)
• Functional Keywords: proteasome, immunoproteasome, bovine spleen, hydrolase
• Biological source: Bos taurus (Bovine); More
• Total number of polymer chains: 28
• Total formula weight: 758873.97

Authors

Xu, C.,Cong, Y. (deposition date: 2020-12-26, release date: 2021-01-20, Last modification date: 2024-03-27)

Primary citation

Chen, J.,Wang, Y.,Xu, C.,Chen, K.,Zhao, Q.,Wang, S.,Yin, Y.,Peng, C.,Ding, Z.,Cong, Y.
Cryo-EM of mammalian PA28 alpha beta-iCP immunoproteasome reveals a distinct mechanism of proteasome activation by PA28 alpha beta.
Nat Commun, 12:739-739, 2021

PubMed Abstract: The proteasome activator PA28αβ affects MHC class I antigen presentation by associating with immunoproteasome core particles (iCPs). However, due to the lack of a mammalian PA28αβ-iCP structure, how PA28αβ regulates proteasome remains elusive. Here we present the complete architectures of the mammalian PA28αβ-iCP immunoproteasome and free iCP at near atomic-resolution by cryo-EM, and determine the spatial arrangement between PA28αβ and iCP through XL-MS. Our structures reveal a slight leaning of PA28αβ towards the α3-α4 side of iCP, disturbing the allosteric network of the gatekeeper α2/3/4 subunits, resulting in a partial open iCP gate. We find that the binding and activation mechanism of iCP by PA28αβ is distinct from those of constitutive CP by the homoheptameric TbPA26 or PfPA28. Our study sheds lights on the mechanism of enzymatic activity stimulation of immunoproteasome and suggests that PA28αβ-iCP has experienced profound remodeling during evolution to achieve its current level of function in immune response.

PubMed: 33531497
DOI: 10.1038/s41467-021-21028-3

Experimental method

ELECTRON MICROSCOPY (3.3 Å)