National Key Laboratory of Medical Molecular Biology, Dept, of Physiology and Pathophysiology, School of Basic Medicine, Peking Union Medical College, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, P,R, China.
Parasit Vectors. 2012 Oct 10;5:227. doi: 10.1186/1756-3305-5-227.
Schistosomiasis is a serious global health problem that afflicts more than 230 million people in 77 countries. Long-term mass treatments with the only available drug, praziquantel, have caused growing concerns about drug resistance. PSD-95/Dlg/ZO-1 (PDZ) domain-containing proteins are recognized as potential targets for the next generation of drug development. However, the PDZ domain-containing protein family in parasites has largely been unexplored.
We present the molecular characteristics of a PDZ domain-containing protein, GIPC3, from Schistosoma japonicum (SjGIPC3) according to bioinformatics analysis and experimental approaches. The ligand binding specificity of the PDZ domain of SjGIPC3 was confirmed by screening an arbitrary peptide library in yeast two-hybrid (Y2H) assays. The native ligand candidates were predicted by Tailfit software based on the C-terminal binding specificity, and further validated by Y2H assays.
SjGIPC3 is a single PDZ domain-containing protein comprised of 328 amino acid residues. Structural prediction revealed that a conserved PDZ domain was presented in the middle region of the protein. Phylogenetic analysis revealed that SjGIPC3 and other trematode orthologues clustered into a well-defined cluster but were distinguishable from those of other phyla. Transcriptional analysis by quantitative RT-PCR revealed that the SjGIPC3 gene was relatively highly expressed in the stages within the host, especially in male adult worms. By using Y2H assays to screen an arbitrary peptide library, we confirmed the C-terminal binding specificity of the SjGIPC3-PDZ domain, which could be deduced as a consensus sequence, -[SDEC]-[STIL]-[HSNQDE]-[VIL]*. Furthermore, six proteins were predicted to be native ligand candidates of SjGIPC3 based on the C-terminal binding properties and other biological information; four of these were confirmed to be potential ligands using the Y2H system.
In this study, we first characterized a PDZ domain-containing protein GIPC3 in S. japonicum. The SjGIPC3-PDZ domain is able to bind both type I and II ligand C-terminal motifs. The identification of native ligand will help reveal the potential biological function of SjGIPC3. These data will facilitate the identification of novel drug targets against S. japonicum infections.
血吸虫病是一种严重的全球健康问题，影响着 77 个国家的 2.3 亿多人。长期使用唯一可用的药物吡喹酮进行大规模治疗，引起了人们对耐药性的日益关注。PDZ 结构域包含蛋白被认为是下一代药物开发的潜在靶点。然而，寄生虫中的 PDZ 结构域包含蛋白家族在很大程度上尚未得到探索。
我们根据生物信息学分析和实验方法，介绍了日本血吸虫 PDZ 结构域包含蛋白 GIPC3 的分子特征。通过酵母双杂交（Y2H）试验筛选任意肽文库，证实了 SjGIPC3 PDZ 结构域的配体结合特异性。Tailfit 软件根据 C 末端结合特异性预测了天然配体候选物，并通过 Y2H 试验进一步验证。
SjGIPC3 是一种由 328 个氨基酸残基组成的单一 PDZ 结构域包含蛋白。结构预测表明，该蛋白的中部区域存在一个保守的 PDZ 结构域。系统发育分析表明，SjGIPC3 和其他吸虫的同源物聚类成一个明确的簇，但与其他门的同源物不同。通过定量 RT-PCR 转录分析，发现 SjGIPC3 基因在宿主内的各个阶段都有相对较高的表达，尤其是在雄性成虫中。通过 Y2H 试验筛选任意肽文库，我们证实了 SjGIPC3-PDZ 结构域的 C 末端结合特异性，可以推断为一个共有序列，-[SDEC]-[STIL]-[HSNQDE]-[VIL]*。此外，根据 C 末端结合特性和其他生物学信息，预测了 SjGIPC3 的 6 个天然配体候选物；其中 4 个使用 Y2H 系统被证实为潜在的配体。
本研究首次对日本血吸虫 PDZ 结构域包含蛋白 GIPC3 进行了特征描述。SjGIPC3-PDZ 结构域能够结合 I 型和 II 型配体的 C 末端基序。鉴定天然配体将有助于揭示 SjGIPC3 的潜在生物学功能。这些数据将有助于识别针对日本血吸虫感染的新型药物靶点。
