title: SUMOylation and deimination of proteins: two epigenetic modifications involved in Giardia encystation.
abstract: SUMOylation, a posttranslational modification of proteins, has been recently described as vital in eukaryotic cells. In a previous work, we analyzed the role of SUMO protein and the genes encoding the putative enzymes of the SUMOylation pathway in the parasite Giardia lamblia. Although we observed several SUMOylated proteins, only the enzyme Arginine Deiminase (ADI) was confirmed as a SUMOylated substrate. ADI is involved in the survival of the parasite and, besides its role in ATP production, it also catalyzes the modification of arginine residues to citrulline in the cytoplasmic tail of surface proteins. During encystation, however, ADI translocates to the nuclei and downregulates the expression of the Cyst Wall Protein 2 (CWP2). In this work, we made site-specific mutation of the ADI SUMOylation site (Lys101) and observed that transgenic trophozoites did not translocate to the nuclei at the first steps of encystation but shuttled in the nuclei late during this process through classic nuclear localization signals. Inside the nuclei, ADI acts as a peptidyl arginine deiminase, being probably involved in the downregulation of CWPs expression and cyst wall formation. Our results strongly indicate that ADI plays a regulatory role during encystation in which posttranslational modifications of proteins are key players.
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina.
authors.forename: Cecilia V
authors.initials: CV
authors.lastname: Vranych
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina.
authors.forename: María R
authors.initials: MR
authors.lastname: Rivero
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Merino
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina.
authors.forename: Gonzalo F
authors.initials: GF
authors.lastname: Mayol
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina.
authors.forename: Nahuel
authors.initials: N
authors.lastname: Zamponi
authors.affiliation: Departamento de Bioquímica Clínica, CIBICI-CONICET, Facultad de Ciencias Químicas, Haya de la Torre y Medina Allende, UNC, 5000 Córdoba, Argentina.
authors.forename: Belkys A
authors.initials: BA
authors.lastname: Maletto
authors.affiliation: Departamento de Bioquímica Clínica, CIBICI-CONICET, Facultad de Ciencias Químicas, Haya de la Torre y Medina Allende, UNC, 5000 Córdoba, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Pistoresi-Palencia
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina.
authors.forename: María C
authors.initials: MC
authors.lastname: Touz
authors.affiliation: Laboratorio de Microbiología e Inmunología, Instituto de Investigación Médica Mercedes y Martín Ferreyra, INIMEC-CONICET, Universidad Nacional de Córdoba, Friuli 2434, 5000 Córdoba, Argentina. Electronic address: aropolo@immf.uncor.edu.
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Rópolo
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology; D003198:Computer Simulation; D015536:Down-Regulation; D044127:Epigenesis, Genetic; D016829:Giardia lamblia / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism*; D006867:Hydrolases / Q000737:chemistry / Q000378:metabolism; D007097:Imines / Q000378:metabolism*; D008239:Lysine / Q000378:metabolism; D008954:Models, Biological; D008969:Molecular Sequence Data; D019913:Nuclear Localization Signals; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D000076342:Protein-Arginine Deiminases; D015800:Protozoan Proteins / Q000378:metabolism*; D033761:Spores, Protozoan / Q000378:metabolism*; D058207:Sumoylation
chemical_list: D007097:Imines; D019913:Nuclear Localization Signals; D015800:Protozoan Proteins; D006867:Hydrolases; D000076342:Protein-Arginine Deiminases; C019723:arginine deiminase; D008239:Lysine
keywords: Arginine deiminase; Encystation; Nuclear localization; Parasites; SUMOylation