1q5r
From Proteopedia
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. 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 Sat May 3 05:53:51 2008
