1q5r: Difference between revisions

[[Image:1q5r.gif|left|200px]]<br /><applet load="1q5r" size="350" color="white" frame="true" align="right" spinBox="true"  

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.

1Q5R is a [http://en.wikipedia.org/wiki/Protein_complex Protein complex] structure of sequences from [http://en.wikipedia.org/wiki/Rhodococcus_erythropolis Rhodococcus erythropolis]. Active as [http://en.wikipedia.org/wiki/Proteasome_endopeptidase_complex Proteasome endopeptidase complex], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.4.25.1 3.4.25.1] Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1Q5R OCA].  

[[Category: Adams, P D.]]

[[Category: Jap, B K.]]

[[Category: Kwon, Y D.]]

''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 14:36:08 2008''