Structural highlights
FunctionRPN1_YEAST Acts as a regulatory subunit of the 26S proteasome which is involved in the ATP-dependent degradation of ubiquitinated proteins.[1] Publication Abstract from PubMedHundreds of pathways for degradation converge at ubiquitin recognition by a proteasome. Here, we found that the five known proteasomal ubiquitin receptors in yeast are collectively nonessential for ubiquitin recognition and identified a sixth receptor, Rpn1. A site ( T1: ) in the Rpn1 toroid recognized ubiquitin and ubiquitin-like ( UBL: ) domains of substrate shuttling factors. T1 structures with monoubiquitin or lysine 48 diubiquitin show three neighboring outer helices engaging two ubiquitins. T1 contributes a distinct substrate-binding pathway with preference for lysine 48-linked chains. Proximal to T1 within the Rpn1 toroid is a second UBL-binding site ( T2: ) that assists in ubiquitin chain disassembly, by binding the UBL of deubiquitinating enzyme Ubp6. Thus, a two-site recognition domain intrinsic to the proteasome uses distinct ubiquitin-fold ligands to assemble substrates, shuttling factors, and a deubiquitinating enzyme. Rpn1 provides adjacent receptor sites for substrate binding and deubiquitination by the proteasome.,Shi Y, Chen X, Elsasser S, Stocks BB, Tian G, Lee BH, Shi Y, Zhang N, de Poot SA, Tuebing F, Sun S, Vannoy J, Tarasov SG, Engen JR, Finley D, Walters KJ Science. 2016 Feb 19;351(6275). pii: aad9421. doi: 10.1126/science.aad9421. PMID:26912900[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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