Structural Studies of SUMO Protein Modification

SUMO蛋白修饰的结构研究

• 批准号: 6895661
• 负责人: CHRISTOPHER D. LIMA
• 金额: $ 30.83万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6895661
• 关键词: chemical conjugate; enzyme model; enzyme substrate complex; genetic models; posttranslational modifications; protein localization; protein structure function; structural biology; ubiquitin

DESCRIPTION (provided by applicant): Modification of cellular proteins by the small Ubiquitin-like Modifier SUMO is essential for eukaryotic nuclear processes and cell cycle progression in yeast. Unlike ubiquitin conjugation, which generally targets proteins for degradation by the proteasome, SUMO modification targets proteins for changes in activity and localization. SUMO conjugation is catalyzed by at least three enzymes, E1, the SUMO activating enzyme, E2, the SUMO conjugation enzyme, and Ulps, SUMO proteolytic processing and deconjugation enzymes. SUMO is translated as a precursor, requiring C-terminal Ulp proteolysis to generate the mature form. SUMO is activated via C-terminal adenylation by E1 and subsequently transferred to an intramolecular cysteine, forming a thioester bond between SUMO and E1. The E1-SUMO thioester is then transferred to an E2 cysteine forming a thioester bond between E2 and SUMO. The E2-SUMO complex is competent to transfer SUMO to lysine receptors on the protein target, forming a stable isopeptide linkage. SUMO modification is reversible, and its removal from lysine is catalyzed by U1p proteases. Pathways modulated by SUMO conjugation include activation of mammalian RanGAP1, p53 transcriptional regulation, MDM2 ubiquitin ligase regulation, I-kappa-B-alpha protection from ubiquitination, PML, PML-RAR, and SP100 nuclear localization, centromere segregation, and septin ring formation, indicating SUMO conjugation as a central regulator in cellular processes involved in nuclear metabolism and cell cycle control.Since few molecular details are known about the SUMO conjugation pathway, structural, biochemical and genetic techniques will be utilized to establish physical models for the sumoylation process by characterizing E1 activation of SUMO, E2 mediated SUMO conjugation, E2-target protein complexes, and complexes between sumoylated proteins, conjugating, and deconjugating enzymes. Genetic and biochemical models will be established for sumoylation through identification of novel SUMO modified proteins. A thorough structure-function analysis of the SUMO pathway will yield insights into its underlying biology.

描述（由申请人提供）：小的泛素样修饰剂SUMO修饰细胞蛋白对酵母真核过程和细胞周期进程至关重要。与泛素偶联不同，泛素偶联通常针对蛋白质进行蛋白酶体降解，而SUMO修饰针对蛋白质的活性和定位变化。SUMO偶联至少由三种酶催化，E1， SUMO活化酶，E2， SUMO偶联酶，Ulps， SUMO蛋白水解加工和解偶联酶。SUMO作为前体被翻译，需要c端Ulp蛋白水解才能产生成熟的形式。SUMO通过E1的c端腺苷化激活，随后转移到分子内半胱氨酸上，在SUMO和E1之间形成硫酯键。然后，E1-SUMO硫酯转移到E2半胱氨酸上，在E2和SUMO之间形成硫酯键。E2-SUMO复合物能够将SUMO转移到蛋白质靶上的赖氨酸受体上，形成稳定的异肽连接。SUMO修饰是可逆的，其从赖氨酸中去除是由U1p蛋白酶催化的。SUMO偶联调节的途径包括哺乳动物RanGAP1的激活、p53转录调控、MDM2泛素连接酶调控、i -kappa- b - α对泛素化的保护、PML、PML- rar和SP100核定位、着丝粒分离和septin环的形成，表明SUMO偶联在参与核代谢和细胞周期控制的细胞过程中起中心调节作用。由于对SUMO偶联途径的分子细节知之甚少，因此将利用结构、生化和遗传技术，通过表征SUMO的E1活化、E2介导的SUMO偶联、E2靶蛋白复合物以及SUMO偶联蛋白、偶联酶和去偶联酶之间的复合物，建立SUMO过程的物理模型。通过鉴定新的SUMO修饰蛋白，将建立SUMO化的遗传和生化模型。对SUMO通路进行彻底的结构-功能分析将有助于深入了解其潜在的生物学。