3mi0
From Proteopedia
Crystal Structure of Mycobacterium Tuberculosis Proteasome at 2.2 A
Structural highlights
FunctionPSA_MYCTU Component of the proteasome core, a large protease complex with broad specificity involved in protein degradation. The M.tuberculosis proteasome is able to cleave oligopeptides not only after hydrophobic but also after basic, acidic and small neutral residues. Among the identified substrates of the M.tuberculosis proteasome are the pupylated FabD, PanB and Mpa proteins. One function of the proteasome is to contribute to M.tuberculosis ability to resist killing by host macrophages, since the core proteasome is essential for persistence of the pathogen during the chronic phase of infection in mice. The mechanism of protection against bactericidal chemistries of the host's immune response probably involves the degradation of proteins that are irreversibly oxidized, nitrated, or nitrosated.[1] [2] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMycobacterium tuberculosis (Mtb) possesses a proteasome system analogous to the eukaryotic ubiquitin-proteasome pathway. Mtb requires the proteasome to resist killing by the host immune system. The detailed assembly process and the gating mechanism of Mtb proteasome have remained unknown. Using cryo-electron microscopy and X-ray crystallography, we have obtained structures of three Mtb proteasome assembly intermediates, showing conformational changes during assembly, and explaining why the beta-subunit propeptide inhibits rather than promotes assembly. Although the eukaryotic proteasome core particles close their protein substrate entrance gates with different amino terminal peptides of the seven alpha-subunits, it has been unknown how a prokaryotic proteasome might close the gate at the symmetry axis with seven identical peptides. We found in the new Mtb proteasome crystal structure that the gate is tightly sealed by the seven identical peptides taking on three distinct conformations. Our work provides the structural bases for assembly and gating mechanisms of the Mtb proteasome. Structural basis for the assembly and gate closure mechanisms of the Mycobacterium tuberculosis 20S proteasome.,Li D, Li H, Wang T, Pan H, Lin G, Li H EMBO J. 2010 Jun 16;29(12):2037-47. Epub 2010 May 11. PMID:20461058[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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