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Title | Structural Analysis of the Bacterial Proteasome Activator Bpa in Complex with the 20S Proteasome. |
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Journal, issue, pages | Structure, Vol. 24, Issue 12, Page 2138-2151, Year 2016 |
Publish date | Dec 6, 2016 |
![]() | Marcel Bolten / Cyrille L Delley / Marc Leibundgut / Daniel Boehringer / Nenad Ban / Eilika Weber-Ban / ![]() |
PubMed Abstract | Mycobacterium tuberculosis harbors proteasomes that recruit substrates for degradation through an ubiquitin-like modification pathway. Recently, a non-ATPase activator termed Bpa (bacterial ...Mycobacterium tuberculosis harbors proteasomes that recruit substrates for degradation through an ubiquitin-like modification pathway. Recently, a non-ATPase activator termed Bpa (bacterial proteasome activator) was shown to support an alternate proteasomal degradation pathway. Here, we present the cryo-electron microscopy (cryo-EM) structure of Bpa in complex with the 20S core particle (CP). For docking into the cryo-EM density, we solved the X-ray structure of Bpa, showing that it forms tight four-helix bundles arranged into a 12-membered ring with a 40 Å wide central pore and the C-terminal helix of each protomer protruding from the ring. The Bpa model was fitted into the cryo-EM map of the Bpa-CP complex, revealing its architecture and striking symmetry mismatch. The Bpa-CP interface was resolved to 3.5 Å, showing the interactions between the C-terminal GQYL motif of Bpa and the proteasome α-rings. This docking mode is related to the one observed for eukaryotic activators with features specific to the bacterial complex. |
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Methods | EM (single particle) / X-ray diffraction |
Resolution | 2.6 - 4.6 Å |
Structure data | ![]() EMDB-4127: EMDB-4128, PDB-5lzp: ![]() PDB-5lfj: ![]() PDB-5lfp: ![]() PDB-5lfq: |
Chemicals | ![]() ChemComp-HOH: |
Source |
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