RESUMO
We have cloned and characterized the homologue of cyclophilin A (CypA) from Trypanosoma brucei brucei, Trypanosoma congolense, Trypanosoma evansi and Trypanosoma vivax. The 1-kilobase African trypanosome CypA complementary DNA contains an open reading frame of 531 base pairs, corresponding to 177 amino acids with a calculated molecular weight of 18,700. The CypA gene is present at one copy/haploid genome in T. brucei, T. congolense and T. vivax and is located on large chromosomes (>3 Mb) in T. brucei. CypA is differentially transcribed in African trypanosomes and is localized in the cytosol as well as in the flagellum. It is also detected in the supernatant of in vitro cultivated parasites. The African trypanosome CypA is unique due to a ten amino acid residue N-terminus extension and a block that includes a three amino acid insertion around position 100 that might result in a differently structured surface. Wild-type recombinant CypA and several mutants were over-expressed in Escherichia coli and purified to >98% homogeneity. Antisera from cattle immunized with a trypanosome fraction containing immunosuppressive activity react strongly against CypA. These data indicate that trypanosome CypA might play an important role in the establishment and maintenance of infections in susceptible animals.
Assuntos
Ciclofilina A/genética , Trypanosoma/genética , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/imunologia , Northern Blotting , Western Blotting , Meios de Cultivo Condicionados/química , Ciclofilina A/imunologia , Ciclofilina A/metabolismo , DNA Complementar/química , DNA Complementar/genética , Escherichia coli/genética , Regulação da Expressão Gênica no Desenvolvimento , Microscopia de Fluorescência , Dados de Sequência Molecular , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes/isolamento & purificação , Proteínas Recombinantes/metabolismo , Alinhamento de Sequência , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Trypanosoma/crescimento & desenvolvimento , Trypanosoma brucei brucei/genética , Trypanosoma brucei brucei/crescimento & desenvolvimento , Trypanosoma congolense/genética , Trypanosoma congolense/crescimento & desenvolvimento , Trypanosoma vivax/genética , Trypanosoma vivax/crescimento & desenvolvimentoRESUMO
We report the genome sequence of Theileria parva, an apicomplexan pathogen causing economic losses to smallholder farmers in Africa. The parasite chromosomes exhibit limited conservation of gene synteny with Plasmodium falciparum, and its plastid-like genome represents the first example where all apicoplast genes are encoded on one DNA strand. We tentatively identify proteins that facilitate parasite segregation during host cell cytokinesis and contribute to persistent infection of transformed host cells. Several biosynthetic pathways are incomplete or absent, suggesting substantial metabolic dependence on the host cell. One protein family that may generate parasite antigenic diversity is not telomere-associated.
Assuntos
Genoma de Protozoário , Linfócitos/parasitologia , Proteínas de Protozoários/genética , Theileria parva/genética , Algoritmos , Animais , Antígenos de Protozoários/genética , Bovinos , Proliferação de Células , Cromossomos/genética , Sequência Conservada , Enzimas/genética , Enzimas/metabolismo , Genes de Protozoários , Linfócitos/citologia , Mitocôndrias/metabolismo , Dados de Sequência Molecular , Organelas/genética , Organelas/fisiologia , Plasmodium falciparum/genética , Estrutura Terciária de Proteína , Proteínas de Protozoários/química , Proteínas de Protozoários/metabolismo , Análise de Sequência de DNA , Sintenia , Telômero/genética , Theileria parva/crescimento & desenvolvimento , Theileria parva/patogenicidade , Theileria parva/fisiologiaRESUMO
At present, there is little information on the phylogenetic diversity of microbial species that inhabit the gastrointestinal tracts of wildlife. To increase understanding in this area, we initiated a characterization of the bacterial diversity in the digestive tracts of three wild African ruminant species namely eland (Taurotragus oryx), Thompson's gazelle (Gazella rufifrons) and Grant's gazelle (Gazella granti), together with a domesticated ruminant species, zebu cattle (Bos indicus), and a non-ruminant species, zebra (Equus quagga). Bacterial diversity was analysed by PCR amplification, sequencing and phylogenetic analysis of 16S ribosomal DNA (rDNA) sequences. A total of 252 full-length 16S rDNA sequences averaging 1,500 base pairs (bp) in length, and an additional 27 partial sequences were obtained and subject to phylogenetic analysis. Using a 98% criterion for similarity, all except for one of the sequences were derived from distinct phylotypes. At least 24 distinct operational taxonomic units (OTU's) could be identified, with the majority of these sequences representing hitherto uncharacterized species and genera. The sequences were generally affiliated with four major bacterial phyla, the majority being members of the Firmicutes (low G+C Gram-positives) related to the genera Clostridium and Ruminococcus. By contrast, with earlier studies using 16S rDNA sequences to assess biodiversity in Bos taurus dairy cattle, Gram-negative bacteria in the Bacteroidales (Prevotella-Bacteroides group) were poorly represented. The lack of redundancy in the 16S rDNA dataset from the five African ungulate species, and the presence of novel sequences not previously described from the gastrointestinal tract of any animal species, highlights the level of diversity that exists in these ecosystems and raises the question as to the functional role of these species in the gastrointestinal tract.