STRUCTURE-FUNCTION RELATIONSHIP OF ISOFLAVONOID O-METHYLTRANSFERASES

异黄酮O-甲基转移酶的结构-功能关系

• 批准号: 7602330
• 负责人: CHANG-JUN LIU
• 金额: $ 0.31万
• 依托单位: BROOKHAVEN SCIENCE ASSOC-BROOKHAVEN LAB
• 依托单位国家: 美国
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-07-01 至 2008-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7602330
• 关键词: Anabolism; Biochemical; Biochemical Genetics; Complex; Computer Retrieval of Information on Scientific Projects Database; Disease; Enzymes; Fabaceae; Family; Family member; Flavonoids; Funding; Grant; Habits; Insecta; Institution; Lead; Mediating; Medicago truncatula; Metabolic; Metabolism; Methylation; Methyltransferase; Molecular; Mutagenesis; Pathway interactions; Plant Model; Plants; Play; Process; Property; Proteins; Research; Research Personnel; Resistance; Resources; Rhizobium; Roentgen Rays; Role; Signal Transduction; Source; Stress; Structure; Structure-Activity Relationship; United States National Institutes of Health; base; in vivo; pathogen; positional cloning; sample fixation; ultraviolet irradiation

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Due to their sessile habit, plants have evolved a complex set of secondary metabolites to protect them from diseases, herbivory and many other environmental stresses. We are employing a combined protein crystallographic/biochemical-genetics approach to understand the details of structures and functions of the key biosynthetic enzymes that underlie the diversity of secondary metabolism. Our current focus involves a group of S-adenosylmethionine (SAM) dependent O-methyltransferases, enzymes that facilitate methylation of polyphenolic (iso)flavoniods (flavonoids and isoflavonoids). Specific methylated forms of (iso)flavonoids have been shown to mediate many processes including resistance to UV irradiation, fungal pathogens, insect attack, and plant-rhizobium signaling for N2 fixation. We recently identified a small family of (iso)flavonoid O-methyltransferases (IOMTs) from the legume model plant Medicago truncatula. However the structural underpinnings governing their biochemical properties are not completely understood, and the catalytic roles these enzymes play in planta remain to be defined. We propose a combined X-ray crystallographic and mutagenesis approach to explore the structural basis for their regiospecific and stereoselective methylations. We also propose to use reverse genetics and metabolic profiling to assess the in vivo functions of the specific IOMT family members for (iso)flavonoid biosynthesis. These structure and function analyses will lead to a more complete understanding of the molecular basis that underlies the complexity of (iso)flavonoid biosynthetic pathways.

该子项目是利用该技术的众多研究子项目之一 资源由 NIH/NCRR 资助的中心拨款提供。子项目和 研究者 (PI) 可能已从 NIH 的另一个来源获得主要资金， 因此可以在其他 CRISP 条目中表示。列出的机构是 对于中心来说，它不一定是研究者的机构。 由于其固着习性，植物进化出了一套复杂的次生代谢产物，以保护它们免受疾病、食草和许多其他环境压力的侵害。 我们正在采用蛋白质晶体学/生化遗传学相结合的方法来了解构成次生代谢多样性的关键生物合成酶的结构和功能的细节。 我们目前的重点涉及一组 S-腺苷甲硫氨酸 (SAM) 依赖性 O-甲基转移酶，这些酶促进多酚 (异) 黄酮类化合物（类黄酮和异黄酮类化合物）的甲基化。 (异)黄酮类化合物的特定甲基化形式已被证明可以介导许多过程，包括对紫外线照射的抵抗力、真菌病原体、昆虫攻击和固定 N2 的植物根瘤菌信号传导。我们最近从豆科模型植物蒺藜苜蓿中鉴定出一个小家族的（异）类黄酮 O-甲基转移酶（IOMT）。 然而，控制其生化特性的结构基础尚不完全清楚，这些酶在植物中发挥的催化作用仍有待确定。 我们提出了一种组合的 X 射线晶体学和诱变方法来探索其区域特异性和立体选择性甲基化的结构基础。我们还建议使用反向遗传学和代谢分析来评估特定 IOMT 家族成员的（异）类黄酮生物合成的体内功能。这些结构和功能分析将有助于更全面地了解（异）类黄酮生物合成途径复杂性的分子基础。