1q5r
From Proteopedia
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The Rhodococcus 20S proteasome with unprocessed pro-peptides
Overview
To understand the role of the pro-peptide in proteasome assembly, we have determined structures of the Rhodococcus proteasome and a mutant form that prevents the autocatalytic removal of its pro-peptides. The structures reveal that the pro-peptide acts as an assembly-promoting factor by linking its own beta-subunit to two adjacent alpha-subunits, thereby providing a molecular explanation for the observed kinetics of proteasome assembly. The Rhodococcus proteasome has been found to have a substantially smaller contact region between alpha-subunits compared to those regions in the proteasomes of Thermoplasma, yeast, and mammalian cells, suggesting that a smaller contact area between alpha-subunits is likely the structural basis for the Rhodococcus alpha-subunits not assembling into alpha-rings when expressed alone. Analysis of all available beta-subunit structures shows that the contact area between beta-subunits within a beta-ring is not sufficient for beta-ring self-assembly without the additional contact provided by the alpha-ring. This appears to be a fail-safe mechanism ensuring that the active sites on the beta-subunits are activated only after proteasome assembly is complete.
About this Structure
1Q5R is a Protein complex structure of sequences from Rhodococcus erythropolis. Active as Proteasome endopeptidase complex, with EC number 3.4.25.1 Full crystallographic information is available from OCA.
Reference
Crystal structures of the Rhodococcus proteasome with and without its pro-peptides: implications for the role of the pro-peptide in proteasome assembly., Kwon YD, Nagy I, Adams PD, Baumeister W, Jap BK, J Mol Biol. 2004 Jan 2;335(1):233-45. PMID:14659753
Page seeded by OCA on Thu Feb 21 14:36:08 2008
