Inhibition of the Arg/N-end rule pathway-mediated proteolysis by dipeptide-mimetic molecules.
Ubr11 in the fission yeast Schizosaccharomyces pombe is an evolutionarily conserved ubiquitin ligase functioning in the Arg/N-end rule pathway, which promotes degradation of substrate proteins via the proteasome. Ubr11 recognizes the N-degron sequence in substrates. The primary N-degron contains a destabilization-inducing N-terminal amino acid, which is either a basic (type 1) or bulky hydrophobic (type 2) residue. Dipeptides are known to inhibit proteolytic degradation via the Arg/N-end rule pathway. Here, I examined the potency of some amino acid- or dipeptide-related molecules in their inhibition of Ubr11/N-end rule-mediated degradation. An amide form of L-arginine and L-tryptophan had weak inhibitory activity for type 1 and type 2 substrates, respectively, although the unmodified amino acid monomer and its carboxymethylated ester were ineffective. Among the naturally occurring dipeptides tested, Lys-Leu and Tyr-Leu showed potent inhibitory activity, but their effect was transient, especially at submillimolar concentrations. L-arginine-β-naphthylamide (Arg-βNA) showed stronger activity than several dipeptides for type 1 substrates, but all Lys-Leu, Tyr-Leu, and Arg-βNA caused growth retardation. The inhibitory activity of the L-phenylalanine carbobenzoxy-hydrazide for type 2 substrates was not very strong, but it prolonged the action of Tyr-Leu at low concentrations and, importantly, did not interfere with cell growth. Apart from their utility, these dipeptidomimetics provide a clue for understanding the determinants of recognition by Ubr ubiquitin ligase and further designing novel inhibitors of the Arg/N-end rule pathway.
Center for Gene Science, Hiroshima University, 1-4-2 Kagamiyama, Higashi-Hiroshima, 739-8527, Japan. kkita@hiroshima-u.ac.jp.
Kenji
K
Kitamura
D020816:Amino Acid Motifs; D004151:Dipeptides / Q000737:chemistry / Q000494:pharmacology*; D059748:Proteolysis / Q000187:drug effects*; D012568:Schizosaccharomyces / Q000187:drug effects / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D004151:Dipeptides; D029702:Schizosaccharomyces pombe Proteins; D044767:Ubiquitin-Protein Ligases; C582094:Ubr11 protein, S pombe
Dipeptidomimetic; N-End rule pathway; S. pombe; Ubiquitin ligase; Ubr protein