Title: Noncanonical MMS2-encoded ubiquitin-conjugating enzyme functions in assembly of novel polyubiquitin chains for DNA repair.

Authors: Hofmann, R M; Pickart, C M

Published In Cell, (1999 Mar 05)

Abstract: Ubiquitin-conjugating enzyme variant (UEV) proteins resemble ubiquitin-conjugating enzymes (E2s) but lack the defining E2 active-site residue. The MMS2-encoded UEV protein has been genetically implicated in error-free postreplicative DNA repair in Saccharomyces cerevisiae. We show that Mms2p forms a specific heteromeric complex with the UBC13-encoded E2 and is required for the Ubc13p-dependent assembly of polyubiquitin chains linked through lysine 63. A ubc13 yeast strain is UV sensitive, and single, double, and triple mutants of the UBC13, MMS2, and ubiquitin (ubiK63R) genes display a comparable phenotype. These findings support a model in which an Mms2p/Ubc13p complex assembles novel polyubiquitin chains for signaling in DNA repair, and they suggest that UEV proteins may act to increase diversity and selectivity in ubiquitin conjugation.

PubMed ID: 10089880

MeSH Terms: Amino Acid Sequence; Animals; Biopolymers/metabolism; Cattle; DNA Repair/physiology*; Fungal Proteins/physiology*; Humans; Ligases/physiology*; Macromolecular Substances; Molecular Sequence Data; Multigene Family; Recombinant Fusion Proteins/physiology; Saccharomyces cerevisiae Proteins*; Saccharomyces cerevisiae/genetics; Saccharomyces cerevisiae/physiology*; Species Specificity; Ubiquitin-Conjugating Enzymes; Ubiquitin-Protein Ligases; Ubiquitins/metabolism*