The ubiquitin-conjugating enzyme (E2) Ube2w ubiquitinates the N terminus of substrates.

Published

Journal Article

Attachment of ubiquitin to substrate is typically thought to occur via formation of an isopeptide bond between the C-terminal glycine residue of ubiquitin and a lysine residue in the substrate. In vitro, Ube2w is nonreactive with free lysine yet readily ubiquitinates substrate. Ube2w also contains novel residues within its active site that are important for its ability to ubiquitinate substrate. To identify the site of modification, we analyzed ubiquitinated substrates by mass spectrometry and found the N-terminal -NH2 group as the site of conjugation. To confirm N-terminal ubiquitination, we generated lysine-less and N-terminally blocked versions of one substrate, the polyglutamine disease protein ataxin-3, and showed that Ube2w can ubiquitinate a lysine-less, but not N-terminally blocked, ataxin-3. This was confirmed with a second substrate, the neurodegenerative disease protein Tau. Finally, we directly sequenced the N terminus of unmodified and ubiquitinated ataxin-3, demonstrating that Ube2w attaches ubiquitin to the N terminus of its substrates. Together these data demonstrate that Ube2w has novel enzymatic properties that direct ubiquitination of the N terminus of substrates.

Full Text

Duke Authors

Cited Authors

  • Scaglione, KM; Basrur, V; Ashraf, NS; Konen, JR; Elenitoba-Johnson, KSJ; Todi, SV; Paulson, HL

Published Date

  • June 2013

Published In

Volume / Issue

  • 288 / 26

Start / End Page

  • 18784 - 18788

PubMed ID

  • 23696636

Pubmed Central ID

  • 23696636

Electronic International Standard Serial Number (EISSN)

  • 1083-351X

International Standard Serial Number (ISSN)

  • 0021-9258

Digital Object Identifier (DOI)

  • 10.1074/jbc.C113.477596

Language

  • eng