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    Aminoacyl-transferases and the N-end rule pathway of prokaryotic/eukaryotic specificity in a human pathogen


    Graciet, Emmanuelle and Hu, Rong-Gui and Piatkov, Konstantin and Rhee, Joon Haeng and Schwarz, Erich M. and Varshavsky, Alexander (2006) Aminoacyl-transferases and the N-end rule pathway of prokaryotic/eukaryotic specificity in a human pathogen. Proceedings of the National Academy of Sciences, 103 (9). pp. 3078-3083. ISSN 1091-6490

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    Abstract

    The N-end rule relates the in vivo half-life of a protein to the identity of its N-terminal residue. Primary destabilizing N-terminal residues (Nd(p)) are recognized directly by the targeting machinery. The recognition of secondary destabilizing N-terminal residues (Nd(s)) is preceded by conjugation of an Nd(p) residue to Nd(s) of a polypeptide substrate. In eukaryotes, ATE1-encoded arginyl-transferases (R(D,E,C*)-transferases) conjugate Arg (R), an Nd(p) residue, to Nd(s) residues Asp (D), Glu (E), or oxidized Cys residue (C*). Ubiquitin ligases recognize the N-terminal Arg of a substrate and target the (ubiquitylated) substrate to the proteasome. In prokaryotes such as Escherichia coli, Nd(p) residues Leu (L) or Phe (F) are conjugated, by the aat-encoded Leu/Phe-transferase (L/F(K,R)-transferase), to N-terminal Arg or Lys, which are Nd(s) in prokaryotes but Nd(p) in eukaryotes. In prokaryotes, substrates bearing the Nd(p) residues Leu, Phe, Trp, or Tyr are degraded by the proteasome-like ClpAP protease. Despite enzymological similarities between eukaryotic R(D,E,C*)-transferases and prokaryotic L/F(K,R)-transferases, there is no significant sequelogy (sequence similarity) between them. We identified an aminoacyl-transferase, termed Bpt, in the human pathogen Vibrio vulnificus. Although it is a sequelog of eukaryotic R(D,E,C*)-transferases, this prokaryotic transferase exhibits a "hybrid" specificity, conjugating Nd(p) Leu to Nd(s) Asp or Glu. Another aminoacyl-transferase, termed ATEL1, of the eukaryotic pathogen Plasmodium falciparum, is a sequelog of prokaryotic L/F(K,R)-transferases (Aat), but has the specificity of eukaryotic R(D,E,C*)-transferases (ATE1). Phylogenetic analysis suggests that the substrate specificity of R-transferases arose by two distinct routes during the evolution of eukaryotes.

    Item Type: Article
    Keywords: proteolysis; ClpAP; ClpS; Aat; bacterial protein transferase;
    Academic Unit: Faculty of Science and Engineering > Biology
    Item ID: 6266
    Depositing User: Emanuelle Graciet
    Date Deposited: 17 Jul 2015 12:01
    Journal or Publication Title: Proceedings of the National Academy of Sciences
    Publisher: National Academy of Sciences
    Refereed: Yes
    URI:

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