Avid interactions underlie the Lys63-linked polyubiquitin binding specificities observed for UBA domains

TitleAvid interactions underlie the Lys63-linked polyubiquitin binding specificities observed for UBA domains
Publication TypeJournal Articles
Year of Publication2009
AuthorsSims JJ, Haririnia A, Dickinson BC, Fushman D, Cohen RE
JournalNature Structural & Molecular Biology
Pagination883 - 889
Date Published2009///
ISBN Number1545-9993
Keywordsapoptosis, basic cellular processes, Biochemistry, biophysics, cell biology, cell cycle, cell surface proteins, cell-cell interactions, checkpoints, chromatin, chromatin remodeling, chromatin structure, content, DNA recombination, DNA repair, DNA replication, Gene expression, Genetics, intracellular signaling, journal, macromolecules, mechanism, membrane processes, molecular, molecular basis of disease, molecular biology, molecular interactions, multi-component complexes, nature publishing group, nature structural molecular biology, nucleic acids, protein degradation, protein folding, protein processing, Proteins, regulation of transcription, regulation of translation, RNA, RNA processing, RNAi, signal transduction, single molecule studies, structure and function of proteins, transcription, translation

Ubiquitin (denoted Ub) receptor proteins as a group must contain a diverse set of binding specificities to distinguish the many forms of polyubiquitin (polyUb) signals. Previous studies suggested that the large class of ubiquitin-associated (UBA) domains contains members with intrinsic specificity for Lys63-linked polyUb or Lys48-linked polyUb, thus explaining how UBA-containing proteins can mediate diverse signaling events. Here we show that previously observed Lys63-polyUb selectivity in UBA domains is the result of an artifact in which the dimeric fusion partner, glutathione S-transferase (GST), positions two UBAs for higher affinity, avid interactions with Lys63-polyUb, but not with Lys48-polyUb. Freed from GST, these UBAs are either nonselective or prefer Lys48-polyUb. Accordingly, NMR experiments reveal no Lys63-polyUb–specific binding epitopes for these UBAs. We reexamine previous conclusions based on GST-UBAs and present an alternative model for how UBAs achieve a diverse range of linkage specificities.