去泛素水解酶Usp25和Usp28的结构与功能研究

发布时间：2018-05-09 10:00

  本文选题：去泛素水解酶 + NMR　； 参考：《中国科学院上海药物研究所》2016年博士论文

【摘要】：泛素化是蛋白质翻译后修饰方式之一,其修饰和去修饰过程分别由泛素化酶组(E1、E2和E3)和去泛素化水解酶(DUB)催化完成。去泛素化蛋白水解酶分为六个亚家族,共有近100个家族成员,他们保证了体内蛋白质泛素化和去泛素化的动态平衡,以实现对细胞生命活动如细胞的代谢、分化、增殖等过程的精确调控。其中USP亚家族最为庞大,成员数量占去泛素化水解酶总量50%以上。近年来的研究报道发现,部分USP家族成员的表达异常和功能紊乱与癌症的发生发展密切相关。由上可知,从结构生物学角度阐明USP的功能调控机制具有重要的科学意义。此外,USP相关的结构生物学研究成果,还可以进一步指导我们理性的设计具有抗癌活性的USP抑制剂,从而为癌症的治疗做出贡献。本论文的研究目标Usp25和Usp28均为USP家族成员,且具有重要的生理功能。Usp25参与肌生成、内质网蛋白质降解、免疫信号调节等多种重要的生理过程,而Usp28的异常表达与癌症的发生、发展密切相关。Usp25与Usp28具有较高的序列同源性,它们都是由一个N端泛素结合结构区域UBR(包含UBA、UIM结构域)和一个核心的催化结构域USP构成。泛素结合结构区域UBR通过参与对泛素底物的识别而在Usp25和Usp28的催化功能展示过程中发挥重要调控作用。此外,需要指出的是,在Usp25和Usp28的泛素结合结构区域中还包含一个和类泛素蛋白SUMO相互作用的区域(SIM),这一事实提示我们SUMO分子有可能参与对Usp25和Usp28酶活功能展示的调控。在本论文中,我们主要采用液体核磁共振以及生化实验等手段研究Usp25和Usp28的N端UBR结构区域在它们的酶活展示过程中所发挥的作用。研究结果显示,UBR结构区域能够特异性的结合泛素以及SUMO2。SUMO2与UBR结构域SIM区的非共价结合,会竞争性的屏蔽UBR结构域与泛素底物之间的相互作用,从而下调Usp25和Usp28的去泛素水解能力。最终,基于已获得的实验结果,我们提出了UBR结构区域调控Usp25和Usp28酶活功能的分子机制模型。
[Abstract]:Ubiquidization is one of the post-translational modification methods of proteins. The process of modification and de-modification is catalyzed by Ubiquitin group E _ (1) E _ 2 and E _ 3) and desuginization hydrolase (DUB) respectively. The diubiquitin hydrolase is divided into six subfamilies of nearly 100 family members. They maintain a dynamic balance between ubiquitization and deubiquification in the body, in order to achieve cell life activities such as cell metabolism and differentiation. Precise regulation of processes such as proliferation. The USP subfamily is the largest, and the number of members accounts for more than 50% of the total ubiquitin hydrolase. Recent studies have found that abnormal expression and dysfunction of some members of USP family are closely related to the occurrence and development of cancer. From the above, it is of great scientific significance to elucidate the functional regulation mechanism of USP from the point of view of structural biology. In addition, the research results of USP-related structural biology can further guide us in the rational design of USP inhibitors with anticancer activity, thus contributing to the treatment of cancer. The objective of this study is that Usp25 and Usp28 are members of USP family, and have important physiological functions. Usp25 is involved in many important physiological processes, such as myogenesis, endoplasmic reticulum protein degradation, immune signal regulation, and the abnormal expression of Usp28 and carcinogenesis. The development of Usp25 is closely related to the sequence homology of Usp28, which consists of a N-terminal ubiquitin binding domain (UBR) and a core catalytic domain (USP). Ubiquitin binding structure region (UBR) plays an important regulatory role in the display of catalytic functions of Usp25 and Usp28 by participating in the recognition of ubiquitin substrates. In addition, it should be pointed out that the region of ubiquitin binding structure of Usp25 and Usp28 also contains a region interacting with ubiquitin protein SUMO, which suggests that the SUMO molecule may be involved in the regulation of Usp25 and Usp28 enzyme activity. In this thesis, we mainly use liquid nuclear magnetic resonance (LNMR) and biochemical experiments to study the role of N-terminal UBR region of Usp25 and Usp28 in the process of enzyme activity display. The results showed that the UBR domain could specifically bind ubiquitin and the noncovalent binding of SIM region of SUMO2.SUMO2 and UBR domain, which would be able to screen the interaction between UBR domain and ubiquitin substrate competitively. Thus, the deoxyuridine hydrolysis ability of Usp25 and Usp28 was down-regulated. Finally, based on the obtained experimental results, we proposed a molecular model for the regulation of Usp25 and Usp28 activity by UBR structural regions.
【学位授予单位】：中国科学院上海药物研究所
【学位级别】：博士
【学位授予年份】：2016
【分类号】：R914

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