Distinct regulation of Ubc13 functions by the two ubiquitin-conjugating enzyme variants Mms2 and Uev1A.
Ubc13, a ubiquitin-conjugating enzyme (Ubc), requires the presence of a Ubc variant (Uev) for polyubiquitination. Uevs, although resembling Ubc in sequence and structure, lack the active site cysteine residue and are catalytically inactive. The yeast Uev (Mms2) incites noncanonical Lys63-linked polyubiquitination by Ubc13, whereas the increased diversity of Uevs in higher eukaryotes suggests an unexpected complication in ubiquitination. In this study, we demonstrate that divergent activities of mammalian Ubc13 rely on its pairing with either of two Uevs, Uev1A or Mms2. Structurally, we demonstrate that Mms2 and Uev1A differentially modulate the length of Ubc13-mediated Lys63-linked polyubiquitin chains. Functionally, we describe that Ubc13-Mms2 is required for DNA damage repair but not nuclear factor kappaB (NF-kappaB) activation, whereas Ubc13-Uev1A is involved in NF-kappaB activation but not DNA repair. Our finding suggests a novel regulatory mechanism in which different Uevs direct Ubcs to diverse cellular processes through physical interaction and alternative polyubiquitination.
Pubmed ID: 16129784 RIS Download
Amino Acid Sequence | Animals | Carrier Proteins | Cell Line | Cell Nucleus | DNA Damage | DNA Repair | DNA-Binding Proteins | Humans | I-kappa B Kinase | Ligases | Lipopolysaccharides | Lysine | Macromolecular Substances | Mice | Molecular Sequence Data | NF-kappa B | Polyubiquitin | Rad51 Recombinase | Recombinant Fusion Proteins | Saccharomyces cerevisiae Proteins | Sequence Alignment | TNF Receptor-Associated Factor 2 | TNF Receptor-Associated Factor 6 | Transcription Factors | Two-Hybrid System Techniques | Ubiquitin-Conjugating Enzymes | Ubiquitin-Protein Ligases