title: Characterization of a RAB5 homologue in Trypanosoma cruzi.
abstract: RAB proteins are small GTPases involved in exocytic and endocytic pathways of eukaryotic cells, controlling vesicle docking and fusion. RABs show a remarkable specificity in subcellular localization, so they can be used as molecular markers for studying protein trafficking in Trypanosoma cruzi, the causal agent of Chagas' disease. RAB5 is a component of early endosomes. It has been identified in kinetoplastids such as Trypanosoma brucei and Leishmania donovani. In this work, we describe the characterization of the complete coding sequence of a RAB5 gene homologue in T. cruzi (TcRAB5, GenBank Accession No. AY730667). It is present as a single copy gene, located at chromosomal bands XIII and XIV. TcRAB5 shares the highest degrees of similarity (71%) and identity (63%) with Trypanosoma brucei rhodesiense RAB5a and contains all five characteristic RAB motifs. TcRAB5 is transcribed as a single 1.5kb mRNA in epimastigotes. Its transcript was also detected in the other two forms of the parasite, metacyclic trypomastigotes and spheromastigotes. The recombinant TcRAB5 protein was able to bind and hydrolyze GTP. The identification of proteins involved in T. cruzi endo- and exocytic pathways may generate cellular compartment markers, an invaluable tool to better understand the vesicular transport in this parasite.
authors.affiliation: Laboratório de Metabolismo Macromolecular Firmino Torres de Castro, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal do Rio de Janeiro, CCS, Cidade Universitária, Rio de Janeiro 21949-900, Brazil.
authors.forename: Júlia Rolão
authors.initials: JR
authors.lastname: Araripe
authors.forename: Fabiane Pereira
authors.initials: FP
authors.lastname: Ramos
authors.forename: Narcisa Leal
authors.initials: NL
authors.lastname: Cunha e Silva
authors.forename: Turán Péter
authors.initials: TP
authors.lastname: Urményi
authors.forename: Rosane
authors.initials: R
authors.lastname: Silva
authors.forename: Carlos Frederico
authors.initials: CF
authors.lastname: Leite Fontes
authors.forename: José Franco
authors.initials: JF
authors.lastname: da Silveira
authors.forename: Edson
authors.initials: E
authors.lastname: Rondinelli
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004789:Enzyme Activation; D006160:Guanosine Triphosphate / Q000737:chemistry*; D006868:Hydrolysis; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014349:Trypanosoma cruzi / Q000201:enzymology* / Q000235:genetics; D020696:rab5 GTP-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D011994:Recombinant Proteins; D006160:Guanosine Triphosphate; D020696:rab5 GTP-Binding Proteins