title: Identification of the phosphorylated residues in TveIF5A by mass spectrometry.
abstract: The initiation factor eIF5A in Trichomonas vaginalis (TveIF5A) is previously shown to undergo hypusination, phosphorylation and glycosylation. Three different pI isoforms of TveIF5A have been reported. The most acidic isoform (pI 5.2) corresponds to the precursor TveIF5A, whereas the mature TveIF5A appears to be the most basic isoform (pI 5.5). In addition, the intermediary isoform (pI 5.3) is found only under polyamine-depleted conditions and restored with exogenous putrescine. We propose that differences in PI are due to phosphorylation of the TveIF5A isoforms. Here, we have identified phosphorylation sites using mass spectrometry. The mature TveIF5A contains four phosphorylated residues (S3, T55, T78 and T82). Phosphorylation at S3 and T82 is also identified in the intermediary TveIF5A, while no phosphorylated residues are found in the precursor TveIF5A. It has been demonstrated that eIF5A proteins from plants and yeast are phosphorylated by a casein kinase 2 (CK2). Interestingly, a gene encoding a protein highly similar to CK2 (TvCK2) is found in T. vaginalis, which might be involved in the phosphorylation of TveIF5A in T. vaginalis.
authors.affiliation: Genomic Sciences Postgraduate, Autonomous University of Mexico City (UACM), CP 03100 Mexico City, Mexico.
authors.forename: Laura Itzel
authors.initials: LI
authors.lastname: Quintas-Granados
authors.affiliation: Genomic Sciences Postgraduate, Autonomous University of Mexico City (UACM), CP 03100 Mexico City, Mexico.
authors.forename: César
authors.initials: C
authors.lastname: López-Camarillo
authors.affiliation: Genomic Sciences Postgraduate, Autonomous University of Mexico City (UACM), CP 03100 Mexico City, Mexico.
authors.forename: Jesús
authors.initials: J
authors.lastname: Fandiño Armas
authors.affiliation: Department of Biochemistry, Faculty of Medicine, National Autonomous University of Mexico, CP 04510 Mexico City, Mexico.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mendoza Hernandez
authors.affiliation: Genomic Sciences Postgraduate, Autonomous University of Mexico City (UACM), CP 03100 Mexico City, Mexico. Electronic address: maria.alvarez@uacm.edu.mx.
authors.forename: María Elizbeth
authors.initials: ME
authors.lastname: Alvarez-Sánchez
mesh_terms: D000595:Amino Acid Sequence; D013058:Mass Spectrometry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010448:Peptide Initiation Factors / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016601:RNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D014246:Trichomonas vaginalis / Q000737:chemistry* / Q000378:metabolism; D000097574:Eukaryotic Translation Initiation Factor 5A
chemical_list: D010448:Peptide Initiation Factors; D020033:Protein Isoforms; D016601:RNA-Binding Proteins; D000097574:Eukaryotic Translation Initiation Factor 5A
keywords: Casein kinase 2; Initiation factor eIF5A; Phosphorylation; Trichomonas vaginalis