2h6j
From Proteopedia
Crystal Structure of the Beta F145A Rhodococcus Proteasome
Structural highlights
Function[PSA1_RHOER] Component of the proteasome core, a large protease complex with broad specificity involved in protein degradation. The R.erythropolis proteasomes are able to cleave oligopeptides after Tyr, Phe and Leu, very poorly after Arg but not after Glu. Thus, displays chymotrypsin-like activity, low trypsin-like activity but no caspase-like activity.[HAMAP-Rule:MF_00289][1] [2] [PSB1_RHOER] Component of the proteasome core, a large protease complex with broad specificity involved in protein degradation. The R.erythropolis proteasomes are able to cleave oligopeptides after Tyr, Phe and Leu, very poorly after Arg but not after Glu. Thus, displays chymotrypsin-like activity, low trypsin-like activity but no caspase-like activity.[HAMAP-Rule:MF_02113][3] [4] 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 PubMedThe processing of propeptides and the maturation of 20S proteasomes require the association of beta rings from two half proteasomes. We propose an assembly-dependent activation model in which interactions between helix (H3 and H4) residues of the opposing half proteasomes are prerequisite for appropriate positioning of the S2-S3 loop; such positioning enables correct coordination of the active-site residue needed for propeptide cleavage. Mutations of H3 or H4 residues that participate in the association of two half proteasomes inhibit activation and prevent, in nearly all cases, the formation of full proteasomes. In contrast, mutations affecting interactions with residues of the S2-S3 loop allow the assembly of full, but activity impacted, proteasomes. The crystal structure of the inactive H3 mutant, Phe145Ala, shows that the S2-S3 loop is displaced from the position observed in wild-type proteasomes. These data support the proposed assembly-dependent activation model in which the S2-S3 loop acts as an activation switch. Proteasome assembly triggers a switch required for active-site maturation.,Witt S, Kwon YD, Sharon M, Felderer K, Beuttler M, Robinson CV, Baumeister W, Jap BK Structure. 2006 Jul;14(7):1179-88. PMID:16843899[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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