DataSheet3_In silico analysis of the HSP90 chaperone system from the African trypanosome, Trypanosoma brucei.docx

African trypanosomiasis is a neglected tropical disease caused by Trypanosoma brucei (T. brucei) and spread by the tsetse fly in sub-Saharan Africa. The trypanosome relies on heat shock proteins for survival in the insect vector and mammalian host. Heat shock protein 90 (HSP90) plays a crucial role in the stress response at the cellular level. Inhibition of its interactions with chaperones and co-chaperones is being explored as a potential therapeutic target for numerous diseases. This study provides an in silico overview of HSP90 and its co-chaperones in both T. brucei brucei and T. brucei gambiense in relation to human and other trypanosomal species, including non-parasitic Bodo saltans and the insect infecting Crithidia fasciculata. A structural analysis of T. brucei HSP90 revealed differences in the orientation of the linker and C-terminal domain in comparison to human HSP90. Phylogenetic analysis displayed the T. brucei HSP90 proteins clustering into three distinct groups based on subcellular localizations, namely, cytosol, mitochondria, and endoplasmic reticulum. Syntenic analysis of cytosolic HSP90 genes revealed that T. b. brucei encoded for 10 tandem copies, while T. b. gambiense encoded for three tandem copies; Leishmania major (L. major) had the highest gene copy number with 17 tandem copies. The updated information on HSP90 from recently published proteomics on T. brucei was examined for different life cycle stages and subcellular localizations. The results show a difference between T. b. brucei and T. b. gambiense with T. b. brucei encoding a total of twelve putative HSP90 genes, while T. b. gambiense encodes five HSP90 genes. Eighteen putative co-chaperones were identified with one notable absence being cell division cycle 37 (Cdc37). These results provide an updated framework on approaching HSP90 and its interactions as drug targets in the African trypanosome.

非洲锥虫病（African trypanosomiasis）是一类由布氏锥虫（Trypanosoma brucei, T. brucei）引发、经采采蝇传播的被忽视热带病，流行于撒哈拉以南非洲区域。锥虫在昆虫媒介与哺乳动物宿主体内生存时，依赖热休克蛋白维持自身功能。热休克蛋白90（Heat shock protein 90, HSP90）在细胞水平的应激反应中发挥关键调控作用。目前学界正探索阻断其与分子伴侣、辅分子伴侣的相互作用，将其作为多种疾病的潜在治疗靶点。
本研究针对布氏锥虫布鲁氏亚种（T. brucei brucei）、布氏锥虫冈比亚亚种（T. brucei gambiense），以及包括非寄生性盐生波多虫（Bodo saltans）、昆虫寄生的簇生短膜虫（Crithidia fasciculata）在内的多种锥虫物种（含人类致病株），开展了HSP90及其辅分子伴侣的计算机模拟分析。对布氏锥虫HSP90的结构解析显示，其连接区域与C端结构域的空间取向与人类HSP90存在显著差异。系统发育分析结果表明，布氏锥虫的HSP90蛋白可根据亚细胞定位分为三类：细胞质基质、线粒体与内质网。
胞质HSP90基因的共线性分析显示，布氏锥虫布鲁氏亚种编码10个串联重复拷贝，布氏锥虫冈比亚亚种仅编码3个串联重复拷贝；硕大利什曼原虫（Leishmania major, L. major）的基因拷贝数最高，达17个串联重复拷贝。本研究还结合近期发表的布氏锥虫蛋白质组学数据，分析了不同生命周期阶段与亚细胞定位下的HSP90表达特征。结果显示布氏锥虫布鲁氏亚种与冈比亚亚种存在明显差异：前者共编码12个推定的HSP90基因，后者仅编码5个。研究团队共鉴定出18个推定的辅分子伴侣，其中一个显著缺失的蛋白为细胞分裂周期蛋白37（cell division cycle 37, Cdc37）。
本研究结果为将HSP90及其相互作用靶点作为非洲锥虫病的药物开发方向提供了更新后的研究框架。