Instituto de Investigação Cientifica Tropical, CIISA, Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Av. da Universidade Técnica, 1300-477 Lisboa, Portugal.
Exp Parasitol. 2011 Oct;129(2):164-74. doi: 10.1016/j.exppara.2011.06.012. Epub 2011 Jul 3.
Besnoitia besnoiti is an apicomplexan parasite responsible for bovine besnoitiosis, a disease with a high prevalence in tropical and subtropical regions and re-emerging in Europe. Despite the great economical losses associated with besnoitiosis, this disease has been underestimated and poorly studied, and neither an effective therapy nor an efficacious vaccine is available. Protein disulfide isomerase (PDI) is an essential enzyme for the acquisition of the correct three-dimensional structure of proteins. Current evidence suggests that in Neosporacaninum and Toxoplasmagondii, which are closely related to B. besnoiti, PDI play an important role in host cell invasion, is a relevant target for the host immune response, and represents a promising drug target and/or vaccine candidate. In this work, we present the nucleotide sequence of the B. besnoiti PDI gene. BbPDI belongs to the thioredoxin-like superfamily (cluster 00388) and is included in the PDI_a family (cluster defined cd02961) and the PDI_a_PDI_a'_c subfamily (cd02995). A 3D theoretical model was built by comparative homology using Swiss-Model server, using as a template the crystallographic deduced model of Tapasin-ERp57 (PDB code 3F8U chain C). Analysis of the phylogenetic tree for PDI within the phylum apicomplexa reinforces the close relationship among B. besnoiti, N. caninum and T. gondii. When subjected to a PDI-assay based on the polymerisation of reduced insulin, recombinant BbPDI expressed in E. coli exhibited enzymatic activity, which was inhibited by bacitracin. Antiserum directed against recombinant BbPDI reacted with PDI in Western blots and by immunofluorescence with B. besnoiti tachyzoites and bradyzoites.
贝氏巴贝斯虫是一种顶复门的寄生虫，可引起牛贝氏巴贝斯虫病，这种疾病在热带和亚热带地区流行率很高，并在欧洲重新出现。尽管与贝氏巴贝斯虫病相关的经济损失巨大，但该疾病被低估且研究不足，既没有有效的治疗方法，也没有有效的疫苗。蛋白二硫键异构酶（PDI）是一种对于蛋白质获得正确三维结构至关重要的酶。目前的证据表明，在与贝氏巴贝斯虫密切相关的新孢子虫和刚地弓形虫中，PDI 在宿主细胞入侵中发挥重要作用，是宿主免疫反应的一个重要靶点，并代表了一个有前途的药物靶点和/或疫苗候选物。在这项工作中，我们展示了贝氏巴贝斯虫 PDI 基因的核苷酸序列。BbPDI 属于硫氧还蛋白样超家族（簇 00388），包含在 PDI_a 家族（簇定义 cd02961）和 PDI_a_PDI_a'_c 亚家族（cd02995）中。使用 Swiss-Model 服务器通过比较同源性构建了一个 3D 理论模型，该模型使用 Tapasin-ERp57 的晶体学推导模型（PDB 代码 3F8U 链 C）作为模板。在顶复门内进行的 PDI 系统发育分析加强了贝氏巴贝斯虫、新孢子虫和刚地弓形虫之间的密切关系。当在基于还原胰岛素聚合的 PDI 测定中时，在大肠杆菌中表达的重组 BbPDI 表现出酶活性，该酶活性被杆菌肽抑制。针对重组 BbPDI 的抗血清在 Western blot 中与 PDI 反应，并在免疫荧光中与贝氏巴贝斯虫速殖子和缓殖子反应。
