蛋白质是生命功能的执行者.生命体中某些关键蛋白的功能异常往往是导致疾病发生的根本原因.这些疾病相关蛋白极有可能成为药物靶点,为新药研发和疾病治疗提供重要线索.PICK1蛋白(protein interacting with Cαkinase1)结合能力广泛、功能多样以及在多种重要疾病(如:癌症、精神分裂症、疼痛、帕金森综合症等)的发生发展过程中发挥潜在的作用,使其成为一个可能的药靶蛋白.PICK1与绝大多数配体蛋白的相互作用是通过其PDZ结构域与配体C末端区域的结合介导的,使PICK1的PDZ结构域成为一个潜在的药物靶点.因此,可以利用生物小分子物质特异性地结合PICK1的PDZ结构域,干扰或阻断PICK1与配体蛋白的天然相互作用,最终达到治疗相关疾病的目的.
HtrA2/Omi is a mammalian mitochondrial serine protease, and was found to have dual roles in mam- malian cells, not only acting as an apoptosis-inducing protein but also maintaining mitochondrial ho- meostasis. PDZ domain is one of the most important protein-protein interaction modules and is in- volved in a variety of important cellular functions, such as signal transduction, degradation of proteins, and formation of cytoskeleton. Recently, it was reported that the PDZ domain of HtrA2/Omi might regulate proteolytic activity through its interactions with ligand proteins. In this study, we rapidly characterized the binding properties of HtrA2/Omi PDZ domain by validation screening of the PDZ ligand library with yeast two-hybrid approach. Then, we predicted its novel ligand proteins in human proteome and reconfirmed them in the yeast two-hybrid system. Finally, we analyzed the smallest networks bordered by the shortest path length between the protein pairs of novel interactions to evaluate the confidence of the identified interactions. The results revealed some novel binding proper- ties of HtrA2/Omi PDZ domain. Besides the reported Class II PDZ motif, it also binds to Class I and Class III motifs, and exhibits restricted variability at P?3, which means that the P?3 residue is selected according to the composition of the last three residues. Seven novel ligand proteins of HtrA2/Omi PDZ domain were discovered, providing significant clues for further clarifying the roles of HtrA2/Omi. Moreover, this study proves the high efficiency and practicability of the newly developed validation screening of candidate ligand library method for binding property characterization of peptide-binding domains.
