Porcel B M, Bontempi E J, Henriksson J, Rydåker M, Aslund L, Segura E L, Pettersson U, Ruiz A M
Instituto Nacional de Chagas, Ministerio de Salud y Acción Social, Buenos Aires, Argentina.
Exp Parasitol. 1996 Dec;84(3):387-99. doi: 10.1006/expr.1996.0127.
Genes encoding a 29-kDa flagellar calcium-binding protein (F29) in Trypanosoma cruzi, strongly homologous to EF-hand calcium-binding protein-encoding genes previously reported in this parasite, were isolated by immunoscreening. F29 is encoded by a number of very similar genes, highly conserved among different T. cruzi isolates. The genes are located on a pair of homologous chromosomes, arranged in one or two clusters of tandem repeats. PCR amplification of Trypanosoma rangeli genomic DNA, using primers derived from the T. cruzi F29 sequence made it possible to isolate the homologous gene in T. rangeli, encoding a 23-kDa protein called TrCaBP. Gene sequence comparisons showed homology to EF-hand calcium-binding proteins from T. cruzi (82.8%), Trypanosoma brucei brucei (60.2%), and Entamoeba histolytica (28.4%). Northern blot analysis revealed that the TrCaBP gene is expressed in T. rangeli as a polyadenylated transcript. The TrCaBP-encoding genes are present in at least 20 copies per cell, organized in tandem arrays, on large T. rangeli chromosomes in some isolates and on two smaller ones in others. This gene, however, seems to be absent from Leishmania.
通过免疫筛选分离出了编码克氏锥虫中一种29 kDa鞭毛钙结合蛋白（F29）的基因，该基因与此前报道的该寄生虫中编码EF手型钙结合蛋白的基因高度同源。F29由多个非常相似的基因编码，在不同的克氏锥虫分离株中高度保守。这些基因位于一对同源染色体上，排列成一个或两个串联重复簇。利用源自克氏锥虫F29序列的引物对兰氏锥虫基因组DNA进行PCR扩增，使得在兰氏锥虫中分离出同源基因成为可能，该基因编码一种名为TrCaBP的23 kDa蛋白。基因序列比较显示，其与克氏锥虫（82.8%）、布氏布氏锥虫（60.2%）和溶组织内阿米巴（28.4%）的EF手型钙结合蛋白具有同源性。Northern印迹分析表明，TrCaBP基因在兰氏锥虫中以多聚腺苷酸化转录本的形式表达。编码TrCaBP的基因在每个细胞中至少有20个拷贝，以串联阵列形式存在，在一些兰氏锥虫分离株中位于大染色体上，在另一些分离株中位于两条较小的染色体上。然而，利什曼原虫中似乎不存在该基因。
