title: PRT1 of Arabidopsis is a ubiquitin protein ligase of the plant N-end rule pathway with specificity for aromatic amino-terminal residues.
abstract: The gene PRT1 of Arabidopsis, encoding a 45-kD protein with two RING finger domains, is essential for the degradation of F-dihydrofolate reductase, a model substrate of the N-end rule pathway of protein degradation. We have determined the function of PRT1 by expression in yeast (Saccharomyces cerevisiae). PRT1 can act as a ubiquitin protein ligase in the heterologous host. The identified substrates of PRT1 have an aromatic residue at their amino-terminus, indicating that PRT1 mediates degradation of N-end rule substrates with aromatic termini but not of those with aliphatic or basic amino-termini. Expression of model substrates in mutant and wild-type plants confirmed this substrate specificity. A ligase activity exclusively devoted to aromatic amino-termini of the N-end rule pathway is apparently unique to plants. The results presented also imply that other known substrates of the plant N-end rule pathway are ubiquitylated by one or more different ubiquitin protein ligases.
authors.affiliation: Institute of Botany, University of Vienna, Rennweg 14, A-1030 Vienna, Austria.
authors.forename: Susanne
authors.initials: S
authors.lastname: Stary
authors.forename: Xiao-jun
authors.initials: XJ
authors.lastname: Yin
authors.forename: Thomas
authors.initials: T
authors.lastname: Potuschak
authors.forename: Peter
authors.initials: P
authors.lastname: Schlögelhofer
authors.forename: Victoria
authors.initials: V
authors.lastname: Nizhynska
authors.forename: Andreas
authors.initials: A
authors.lastname: Bachmair
mesh_terms: D024322:Amino Acids, Aromatic / Q000378:metabolism*; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics; D029681:Arabidopsis Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013762:Tetrahydrofolate Dehydrogenase / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D024322:Amino Acids, Aromatic; D029681:Arabidopsis Proteins; D004268:DNA-Binding Proteins; D004791:Enzyme Inhibitors; D013762:Tetrahydrofolate Dehydrogenase; C113475:PRT1 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases