Structure-Function Studies on the Sulfate Activating Enzymes

硫酸盐活化酶的结构-功能研究

• 批准号: 9904003
• 负责人: Irwin Segel
• 金额: $ 48万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-01 至 2004-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9904003&HistoricalAwards=false
• 关键词: Structure; Function; Studies; Sulfate; Activating

9904003Segel, Fisher This research examines the structural features underlying the catalyticand regulatory properties of the "sulfate activating enzymes", ATPsulfurylase and APS kinase. These enzymes catalyze, in order, the first tworeactions in the assimilation of inorganic sulfate. The investigation focuses on the homo-hexameric ATP sulfurylase of Penicillium chrysogenum,which is allosterically inhibited by PAPS. This feedback process is uniqueto filamentous fungi, very likely reflecting the fact that PAPS is a majorbranch point metabolite in fungi, but not in other organisms. Theallosteric domain of fungal ATP sulfurylase is located in the C-terminalregion of the polypeptide chain and has a high degree of homology with APSkinase. Experiments are designed to determine (a) the relationshipbetween the three dimensional structure of the allosteric domain and thatof true APS kinase and (b) the structural nature of the transition inducedby the allosteric effector. P. chrysogenum APS kinase, a homodimer, isalso be studied in order to establish the structural basis of (a) the highspecificity for sulfonucleotides, (b) the compulsory ordered binding ofsubstrates (is it kinetic or structurally-based?), and (c) the relationshipbetween subunit association and formation of the active site.Sulfur is one of the six major elements that compose living cells. Keybiological molecules that contain sulfur include the protein amino acids,cysteine and methionine, and the vitamins pantothenic acid, biotin, andthiamin. Most of the sulfur on the Earth's surface (in the soil and oceans,etc.) is present as inorganic sulfate. This project focuses on the structures and functions of ATP sulfurylase and APS kinase, enzymes that catalyze the first two reactions in the incorporation of inorganic sulfate into biomolecules. The enzymes will be purified from the filamentous fungus, Penicillium chrysogenum (which produces another important sulfur compound, penicillin.)

9904003Segel, Fisher 这项研究检查了“硫酸盐激活酶”、ATP 磺化酶和 APS 激酶的催化和调节特性背后的结构特征。这些酶按顺序催化无机硫酸盐同化中的前两个反应。研究重点是产黄青霉的同型六聚体 ATP 硫酸化酶，该酶受到 PAPS 的变构抑制。这种反馈过程是丝状真菌所独有的，很可能反映出 PAPS 是真菌中的主要分支点代谢物，但在其他生物体中不是。真菌ATP硫酸化酶的变构结构域位于多肽链的C末端区域，与APS激酶具有高度的同源性。 实验旨在确定 (a) 变构域的三维结构与真正的 APS 激酶的三维结构之间的关系，以及 (b) 变构效应子诱导的转变的结构性质。 还对 P. chrysogenum APS 激酶（一种同二聚体）进行了研究，以建立以下结构基础：(a) 磺基核苷酸的高度特异性，(b) 底物的强制有序结合（是基于动力学还是基于结构？），以及 (c) 亚基关联与活性位点形成之间的关系。硫是构成生命的六种主要元素之一 细胞。含硫的关键生物分子包括蛋白质氨基酸、半胱氨酸和蛋氨酸，以及维生素泛酸、生物素和硫胺素。地球表面（土壤和海洋等）的硫大部分以无机硫酸盐的形式存在。该项目重点研究 ATP 硫酸化酶和 APS 激酶的结构和功能，这两种酶催化无机硫酸盐掺入生物分子的前两个反应。这些酶将从丝状真菌产黄青霉（产生另一种重要的硫化合物青霉素）中纯化。