Solution structure of Vps27 UIM-ubiquitin complex important for endosomal sorting and receptor downregulation

Kurt A. Swanson, Richard S. Kang, Svetoslava D. Stamenova, Linda Hicke, Ishwar Radhakrishnan*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

171 Scopus citations

Abstract

Monoubiquitylation is a well-characterized signal for the internalization and sorting of integral membrane proteins to distinct cellular organelles. Recognition and transmission of monoubiquitin signals is mediated by a variety of ubiquitin-binding motifs such as UIM, UBA, UEV, VHS and CUE in endocytic proteins. The yeast Vps27 protein requires two UIMs for efficient interactions with ubiquitin and for sorting cargo into multivesicular bodies. Here we show that the individual UIMs of Vps27 exist as autonomously folded α-helices that bind ubiquitin independently, non-cooperatively and with modest affinity. The Vps27 N-terminal UIM engages the Leu8-Ile44-Val70 hydrophobic patch of ubiquitin through a helical surface conserved in UIMs of diverse proteins, including that of the S5a proteasomal regulatory subunit. The Leu8-Ile44-Val70 ubiquitin surface is also the site of interaction for CUE and UBA domains in endocytic proteins, consistent with the view that ubiquitin-binding endocytic proteins act serially on the same monoubiquitylated cargo during transport from cell surface to the lysosome.

Original languageEnglish (US)
Pages (from-to)4597-4606
Number of pages10
JournalEMBO Journal
Volume22
Issue number18
DOIs
StatePublished - Sep 15 2003

Keywords

  • Endocytosis
  • Monoubiquitin signaling
  • Protein sorting
  • UIM
  • Ubiquitin-binding motif

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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