title: The Ubp6 family of deubiquitinating enzymes contains a ubiquitin-like domain: SUb.
abstract: A sequence motif that is Similar to Ubiquitin (SUb) has been identified in the Saccharomyces cerevisiae ubiquitin-specific protease Ubp6. SUb is conserved in all known Ubp6 homologues from a spectrum of eukaryotic species and is also present in a group of hypothetical proteins of unknown function (Unk1-3) present in sequence databases. An N-terminal deletion mutant of Ubp6 that lacks SUb is still capable of cleaving alpha-linked ubiquitin fusions, suggesting that SUb forms a separate domain to the catalytic core of Ubp6 and demonstrating that it is not required for in vitro cleavage activity. A homology model of the 78 N-terminal amino acids of human Ubp6, based on the known fold of ubiquitin, is presented. In human Ubp6, SUb shares only 20% sequence identity with ubiquitin. Even weaker similarity occurs between S. cerevisiae SUb and ubiquitin. The homology model supports a ubiquitin-like fold for SUb and suggests that two conserved Lys residues, corresponding to Lys48 and Lys63 of ubiquitin, are functionally important.
authors.affiliation: Molecular Genetics Group, John Curtin School of Medical Research, Australian National University, Canberra ACT.
authors.forename: A M
authors.initials: AM
authors.lastname: Wyndham
authors.forename: R T
authors.initials: RT
authors.lastname: Baker
authors.forename: G
authors.initials: G
authors.lastname: Chelvanayagam
mesh_terms: D000595:Amino Acid Sequence; D017124:Conserved Sequence; D010450:Endopeptidases / Q000737:chemistry* / Q000235:genetics; D005091:Exons; D005656:Fungal Proteins / Q000737:chemistry*; D006801:Humans; D007438:Introns; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid; D014452:Ubiquitins / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; D010450:Endopeptidases; C109028:UBP6 protein, S cerevisiae