title: An Entamoeba histolytica ADP-ribosyl transferase from the diphtheria toxin family modifies the bacterial elongation factor Tu.
abstract: ADP-ribosyl transferases are enzymes involved in the post-translational modification of proteins; they participate in multiple physiological processes, pathogenesis and host-pathogen interactions. Several reports have characterized the functions of these enzymes in viruses, prokaryotes and higher eukaryotes, but few studies have reported ADP-ribosyl transferases in lower eukaryotes, such as parasites. The locus EHI_155600 from Entamoeba histolytica encodes a hypothetical protein that possesses a domain from the ADP-ribosylation superfamily; this protein belongs to the diphtheria toxin family according to a homology model using poly-ADP-ribosyl polymerase 12 (PARP12 or ARTD12) as a template. The recombinant protein expressed in Escherichia coli exhibited in vitro ADP-ribosylation activity that was dependent on the time and temperature. Unlabeled βNAD(+), but not ADP-ribose, competed in the enzymatic reaction using biotin-βNAD(+) as the ADP-ribose donor. The recombinant enzyme, denominated EhToxin-like, auto-ADP-ribosylated and modified an acceptor from E. coli that was identified by MS/MS as the elongation factor Tu (EF-Tu). To the best of our knowledge, this is the first report to identify an ADP-ribosyl transferase from the diphtheria toxin family in a protozoan parasite. The known toxins from this family (i.e., the diphtheria toxin, the Pseudomonas aeruginosa toxin Exo-A, and Cholix from Vibrio cholerae) modify eukaryotic elongation factor two (eEF-2), whereas the amoeba EhToxin-like modified EF-Tu, which is another elongation factor involved in protein synthesis in bacteria and mitochondria.
authors.affiliation: Departamento de Biologia, DCNE, Universidad de Guanajuato, Colonia Noria Alta, CP 36050 Guanajuato, Mexico. Electronic address: edilia@ugto.mx.
authors.forename: Eva E
authors.initials: EE
authors.lastname: Avila
authors.affiliation: Departamento de Biologia, DCNE, Universidad de Guanajuato, Colonia Noria Alta, CP 36050 Guanajuato, Mexico.
authors.forename: Orlando I
authors.initials: OI
authors.lastname: Rodriguez
authors.affiliation: Departamento de Biologia, DCNE, Universidad de Guanajuato, Colonia Noria Alta, CP 36050 Guanajuato, Mexico.
authors.forename: Jaqueline A
authors.initials: JA
authors.lastname: Marquez
authors.affiliation: Departments of Biochemistry and Microbiology & Immunology, McGill University, Life Sciences Complex, Francesco Bellini Building, 3649 Promenade Sir William Osler, Room 470, Montreal, QC H3G 0B1, Canada.
authors.forename: Albert M
authors.initials: AM
authors.lastname: Berghuis
mesh_terms: D036002:ADP Ribose Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004167:Diphtheria Toxin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004748:Entamoeba histolytica / Q000201:enzymology*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D008958:Models, Molecular; D010444:Peptide Elongation Factor Tu / Q000737:chemistry / Q000378:metabolism*; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D004167:Diphtheria Toxin; D011994:Recombinant Proteins; D036002:ADP Ribose Transferases; D010444:Peptide Elongation Factor Tu
keywords: ADP-ribosylation; Elongation factor; Entamoeba; Posttranslational modification; Protozoan parasites; Toxin