title: An early ancestor in the evolution of splicing: a Trypanosoma cruzi serine-arginine-rich protein (TcSR) is functional in cis-splicing.
abstract: A novel serine-arginine-rich protein designated TcSR was identified in Trypanosoma cruzi. The deduced amino acid sequence reveals that TcSR is a member of the SR protein family of splicing factors that contains two RNA-binding domains at the N-terminal side and several serine-arginine repeats at the COOH-terminus. Over expression of either TcSR or the human SR-protein associated splicing factor/splicing factor 2 (ASF/SF2) in wild-type Schizosaccharomyces pombe, provoked an elongated phenotype similar to that of fission yeast over expressing the SR-containing splicing factor Prp2, a U2AF(65) orthologue. When a double mutant strain lacking two SR protein-specific protein kinases was used, expression of TcSR or human SR ASF/SF2 splicing factor reverted the mutant to a wild-type phenotype. Transient expression of TcSR in HeLa cells stimulated the inclusion of the EDI exon of human fibronectin in an in vivo functional alternative cis-splicing assay. Inclusion was dependent on a splicing enhancer sequence present in the EDI exon. In addition, TcSR and peptides carrying TcSR-RS domain sequences were phosphorylated by a human SR protein kinase. These results indicate that TcSR is a member of the SR splicing network and that some components common to the trans- and cis-splicing machineries evolved from the early origins of the eukaryotic lineage.
authors.affiliation: Facultad de Ciencias Exactas y Naturales, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Consejo Nacional de Investigaciones Científicas y Técnicas, Universidad de Buenos Aires, Buenos Aires, Argentina.
authors.forename: Daniel
authors.initials: D
authors.lastname: Portal
authors.forename: Joaquín M
authors.initials: JM
authors.lastname: Espinosa
authors.forename: Guillermo S
authors.initials: GS
authors.lastname: Lobo
authors.forename: Sebastián
authors.initials: S
authors.lastname: Kadener
authors.forename: Claudio A
authors.initials: CA
authors.lastname: Pereira
authors.forename: Manuel
authors.initials: M
authors.lastname: De La Mata
authors.forename: Zhaohua
authors.initials: Z
authors.lastname: Tang
authors.forename: Ren-Jang
authors.initials: RJ
authors.lastname: Lin
authors.forename: Alberto R
authors.initials: AR
authors.lastname: Kornblihtt
authors.forename: Francisco E
authors.initials: FE
authors.lastname: Baralle
authors.forename: Mirtha M
authors.initials: MM
authors.lastname: Flawiá
authors.forename: Héctor N
authors.initials: HN
authors.lastname: Torres
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000032:analysis*; D019143:Evolution, Molecular; D006367:HeLa Cells; D006801:Humans; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D012326:RNA Splicing; D012568:Schizosaccharomyces / Q000235:genetics; D016415:Sequence Alignment; D012694:Serine / Q000032:analysis*; D014349:Trypanosoma cruzi / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology
chemical_list: D015800:Protozoan Proteins; D012694:Serine; D001120:Arginine