Tran T, Claes F, Dujardin J C, Buscher P
Institute of Tropical Medicine, Department of Parasitology, Nationalestraat 155, B-2000 Antwerp, Belgium.
Parasitology. 2006 Nov;133(Pt 5):613-21. doi: 10.1017/S0031182006000953. Epub 2006 Sep 4.
In Trypanosoma brucei brucei, an invariant surface glycoprotein of molecular weight 75 kDa (ISG75) is uniformly distributed over the surface of a trypanosome and is specific for bloodstream-form parasites. For the other taxa of the Trypanozoon subgenus no data about this surface molecule are available. Therefore, we investigated the ISG75 in the genomes of several pathogenic Trypanozoon by Southern blot, PCR and RT-PCR and sequence analysis. This study reveals that (i) all members of the Trypanozoon subgenus, i.e. T. b. brucei, T. b. gambiense, T. b. rhodesiense, T. evansi and T. equiperdum, harbour ISG75 as multiple gene copies with at least 4-16 copies per genome; (ii) ISG75 gDNA and cDNA sequences are distributed in 2 groups that share at least 75% and 77% identity respectively; (iii) sequences from both groups are transcribed in all species and subspecies of the Trypanozoon subgenus; (iv) the main differences between group I and group II are located in the variable region at the amino-terminus of the putative proteins; (v) however, all the sequences in both groups have some well-conserved features, such as the cysteine residues, an amino-terminal cleavable signal peptide, a single alpha-helix transmembrane domain and a cytoplasmic domain at the carboxy-terminus.
在布氏布氏锥虫中，一种分子量为75 kDa的不变表面糖蛋白（ISG75）均匀分布在锥虫表面，且是血液型寄生虫所特有的。对于锥虫亚属的其他分类群，尚无关于这种表面分子的可用数据。因此，我们通过Southern印迹、PCR、RT-PCR和序列分析，对几种致病性锥虫基因组中的ISG75进行了研究。本研究表明：（i）锥虫亚属的所有成员，即布氏布氏锥虫、布氏冈比亚锥虫、布氏罗德西亚锥虫、伊氏锥虫和马媾疫锥虫，均含有多个ISG75基因拷贝，每个基因组至少有4 - 16个拷贝；（ii）ISG75的gDNA和cDNA序列分为两组，分别具有至少75%和77%的同一性；（iii）两组序列在锥虫亚属的所有物种和亚种中均有转录；（iv）I组和II组之间的主要差异位于假定蛋白质氨基末端的可变区；（v）然而，两组中的所有序列都有一些保守特征，如半胱氨酸残基、氨基末端可裂解信号肽、单个α-螺旋跨膜结构域和羧基末端的细胞质结构域。
