Caenorhabditis elegans UBC-1, a ubiquitin-conjugating enzyme homologous to yeast RAD6/UBC2, contains a novel carboxy-terminal extension that is conserved in nematodes

DNA Cell Biol. 1995 Oct;14(10):883-91. doi: 10.1089/dna.1995.14.883.


The RAD6/UBC2 gene from Saccharomyces cerevisiae encodes a ubiquitin-conjugating enzyme involved in DNA repair, induced mutagenesis, and sporulation. Here we report the isolation and characterization of the Caenorhabditis elegans RAD6 homolog designated ubc-1. Ubc-1 encodes a 21.5-kD protein that shares considerable identity with RAD6 (66%) as well as with other RAD6 homologs, including Schizosaccharomyces pombe rhp6+ (70%), Drosophila melanogaster Dhr6 (83%), and the two human homologs HHR6A and HHR6B (84% and 83%, respectively). However, UBC-1 is distinct in being the only known RAD6 homolog, other than RAD6 itself, with a carboxy-terminal extension. Analysis of UBC-1 homologs from C. briggsae and Ascaris suum show that the presence of the carboxy-terminal extension is conserved in nematodes. When constitutively expressed from the yeast promoter ADH1, ubc-1 complements the DNA repair functions in a S. cerevisiae rad6 delta mutant. Surprisingly, ubc-1 fails to complement the sporulation function of RAD6, despite its possession of an acidic carboxy-terminal tail. C. elegans UBC-1 is capable of forming a thiol-ester bond with ubiquitin, but, unlike RAD6, is unable to transfer ubiquitin to histone H2B in vitro. Both cis and trans splicing are involved in the maturation of the ubc-1 transcript. The presence of the SL2 trans-splice leader in the ubc-1 transcript suggests that ubc-1 may be co-transcribed as part of a polycistronic message.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Ascaris / chemistry
  • Base Sequence
  • Caenorhabditis elegans / genetics
  • Caenorhabditis elegans / metabolism*
  • Caenorhabditis elegans Proteins*
  • Drosophila melanogaster / chemistry
  • Evolution, Molecular
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / physiology
  • Genes, Fungal
  • Genes, Helminth*
  • Genetic Complementation Test
  • Helminth Proteins / chemistry*
  • Helminth Proteins / genetics
  • Helminth Proteins / physiology
  • Humans
  • Ligases / chemistry*
  • Ligases / genetics
  • Ligases / physiology
  • Molecular Sequence Data
  • RNA Splicing
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins*
  • Schizosaccharomyces / chemistry
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Species Specificity
  • Ubiquitin-Conjugating Enzymes
  • Ubiquitins / metabolism


  • Caenorhabditis elegans Proteins
  • Fungal Proteins
  • Helminth Proteins
  • Saccharomyces cerevisiae Proteins
  • Ubiquitins
  • RAD6 protein, S cerevisiae
  • UBC1 protein, S cerevisiae
  • UBE2A protein, human
  • UBE2B protein, human
  • Ubiquitin-Conjugating Enzymes
  • ubc-1 protein, C elegans
  • Ligases

Associated data

  • GENBANK/U08139