The structure of the 26S proteasome subunit Rpn2 reveals its PC repeat domain as a closed toroid of two concentric α-helical rings

Jun He, Kiran Kulkarni, Paula C.A. Da Fonseca, Dasha Krutauz, Michael H. Glickman, David Barford, Edward P. Morris

Research output: Contribution to journalArticlepeer-review

Abstract

The 26S proteasome proteolyses ubiquitylated proteins and is assembled from a 20S proteolytic core and two 19S regulatory particles (19S-RP). The 19S-RP scaffolding subunits Rpn1 and Rpn2 function to engage ubiquitin receptors. Rpn1 and Rpn2 are characterized by eleven tandem copies of a 35-40 amino acid repeat motif termed the proteasome/cyclosome (PC) repeat. Here, we reveal that the eleven PC repeats of Rpn2 form a closed toroidal structure incorporating two concentric rings of α helices encircling two axial α helices. A rod-like N-terminal domain consisting of 17 stacked α helices and a globular C-terminal domain emerge from one face of the toroid. Rpn13, an ubiquitin receptor, binds to the C-terminal 20 residues of Rpn2. Rpn1 adopts a similar conformation to Rpn2 but differs in the orientation of its rod-like N-terminal domain. These findings have implications for understanding how 19S-RPs recognize, unfold, and deliver ubiquitylated substrates to the 20S core.

Original languageEnglish
Pages (from-to)513-521
Number of pages9
JournalStructure
Volume20
Issue number3
DOIs
StatePublished - 7 Mar 2012

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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