Evidence for cooperative and domain-specific binding of the signal transducing adaptor molecule 2 (STAM2) to Lys63-linked diubiquitin

Anja Lange, Carlos Castañeda, Daniela Hoeller, Jean Marc Lancelin, David Fushman, Olivier Walker

Research output: Contribution to journalArticle

17 Scopus citations

Abstract

As the upstream component of the ESCRT (endosomal sorting complexes required for transport) machinery, the ESCRT-0 complex is responsible for directing ubiquitinated membrane proteins to the multivesicular body pathway. ESCRT-0 is formed by two subunits known as Hrs (hepatocyte growth factor-regulated substrate) and STAM (signal transducing adaptor molecule), both of which harbor multiple ubiquitin-binding domains (UBDs). In particular, STAM2 possesses two UBDs, the VHS (Vps27/Hrs/Stam) and UIM (ubiquitin interacting motif) domains, connected by a 20-amino acid flexible linker. In the present study, we report the interactions of the UIM domain and VHS-UIM construct of STAM2 with monoubiquitin (Ub), Lys48- and Lys63-linked diubiquitins. Our results demonstrate that the UIM domain alone binds monoubiquitin, Lys48- and Lys63-linked diubiquitins with thesame affinity and in the same binding mode. Interestingly, binding of VHS-UIM to Lys63-linked diubiquitin is not only avid, but also cooperative. We also show that the distal domain of Lys63-linked diubiquitin stabilizes the helical structure of the UIM domain and that the corresponding complex adopts a specific structural organization responsible for its greater affinity. In contrast, binding of VHS-UIM to Lys48-linked diubiquitin and monoubiquitin is not cooperative and does not show any avidity. These results may explain the better sorting efficiency of some cargoes polyubiquitinated with Lys63-linked chains over monoubiquitinated cargoes or those tagged with Lys48-linked chains.

Original languageEnglish (US)
Pages (from-to)18687-18699
Number of pages13
JournalJournal of Biological Chemistry
Volume287
Issue number22
DOIs
StatePublished - May 25 2012

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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