RESUMO
We report here the isolation and characterisation of genomic and cDNA clones encoding a Serine-, Alanine-, and Proline-rich protein (SAP) of Trypanosoma cruzi metacyclic trypomastigotes. The deduced peptides translated from these clones were characterised by a high content of residues of alanine, proline, serine, glycine, valine, and threonine distributed in several repeats: P(2-4), S(2-3), A(2-3), AS, SA, PA, AP, SP, PS, and TP. The repeats are partially homologous to the serine-, alanine-, and proline-containing motifs of Leishmania major and Leishmania mexicana proteophosphoglycans. Genes coding for SAP are part of a polymorphic family whose members are linked to members of gp85/sialidase and mucin-like gene families. This is consistent with the hypothesis that this genetic organisation could be a means by which T. cruzi co-ordinates the expression of major surface proteins.
Assuntos
Genoma de Protozoário , Proteínas de Protozoários/genética , Trypanosoma cruzi/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Clonagem Molecular , DNA Complementar , Dados de Sequência Molecular , Família Multigênica , Proteínas de Protozoários/química , Proteínas de Protozoários/isolamento & purificação , Proteínas de Protozoários/metabolismo , Análise de Sequência de DNA , Trypanosoma cruzi/crescimento & desenvolvimento , Trypanosoma cruzi/metabolismoRESUMO
We have isolated a clone of Trypanosoma cruzi genomic DNA, lambda 3b2-5, which contains sequences that are reiterated in the genome. Northern blot analysis showed that clone 3b2-5 hybridizes to 1,200-5,000 bases different mRNA species. The number of mRNAs species hybridized to clone 3b2-5 exceeds its coding capacity showing that this clone carries sequences that are common to several mRNAs species and conserved in the poly A(+) RNA. These sequences are not homologous to the T. cruzi spliced leader sequence, since clone 3b2-5 does not hybridize to a synthetic 20 nucleotide complementary to the spliced leader sequence. Clone 3b2-5 does not hybridize to DNA and RNA from several genera of Trypanosomatidae and other Trypanosoma species indicating that it carries T. cruzi species-specific sequences.
Assuntos
DNA/genética , RNA Mensageiro/genética , Sequências Repetitivas de Ácido Nucleico , Trypanosoma cruzi/genética , Animais , Northern Blotting , Southern Blotting , Biblioteca Genômica , Família Multigênica , Homologia de Sequência do Ácido Nucleico , Especificidade da EspécieRESUMO
Intact RNAs were isolated from epimastigote forms of different Trypanosoma cruzi strains. Translation of the mRNAs using rabbit reticulocyte lysate and analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed protein profiles comparable to those observed by labeling cells in vivo. No major interstrain differences were observed in the patterns of the polypeptides synthesized in vitro and in vivo, indicating that metabolic proteins are similar among distinct strains. Several T. cruzi polypeptides produced in the rabbit reticulocyte lysate system were immunoprecipitated by specific antisera. The patterns of antigenic polypeptides recognized by antisera raised against epimastigotes from different strains were also very similar.