Collaborative Research: Atomic Structure Determination of ADPGlucose Pyrophosphorylase

糖原和淀粉是几乎所有生物的主要储能化合物，也是从植物中获得的重要能量成分。ADP-葡萄糖焦磷酸化酶(ADPGlc-Ppase)催化葡萄糖-1-磷酸和三磷酸腺苷转化为ADP-葡萄糖和焦磷酸，是细菌糖原和植物淀粉生物合成的关键调控步骤。ADPGlc Ppase的调节是通过与许多激活剂和抑制剂的结合来介导的，其中许多是关键的代谢中间产物。本研究利用根癌农杆菌ADPGlc Ppase(Ag.t.)这是由果糖-6-磷酸和丙酮酸调节的。本项目概述了Ag.t的X射线晶体结构研究。ADPGlc Ppase检测底物结合、变构效应结合以及激活机制。与X射线结晶学有关的几个障碍已经被克服，包括晶化和重原子衍生化用于物相测定。一旦确定了ADPGlc Ppase蛋白家族中一个成员的三维结构，同源建模就可以用来构建该家族中其他蛋白的合理结构。作为生产可再生和可生物降解碳源的主要控制点，ADPGlc PPase是蛋白质工程的一个有吸引力的酶靶标。了解ADPGlc Ppase酶家族的调控对于酶的生物工程是必要的，并可能导致对酶进行合理的蛋白质工程以增加淀粉产量

Glycogen and starch serve as major energy storage compounds for nearly all-living organisms and are an important energy component obtained fromplants. ADP-glucose pyrophosphorylase (ADPGlc Ppase) catalyzes theconversion of glucose-1-phosphate and ATP to ADP-glucose andpyrophosphate and is a key regulated step in both bacterial glycogen andplant starch biosynthesis. ADPGlc Ppase regulation is mediated by thebinding of a number of activators and inhibitors, many of which are keymetabolic intermediates. This research utilizes the ADPGlc Ppase enzymefrom the bacteria Agrobacterium tumefaciens (Ag.t.) that is regulated by fructose-6-phosphate and pyruvate. This project outlines x-ray crystal structuralstudies on Ag.t. ADPGlc Ppase to examine substrate binding, allostericeffector binding, and the mechanism of activation. Several roadblocksassociated with x-ray crystallography have already been overcome includingcrystallization and heavy atom derivitization for phase determination. Oncethe three-dimensional structure of one member of the ADPGlc Ppase proteinfamily is determined homology modeling can be used to construct reasonablestructures of the other proteins in the family. As a major control point for theproduction of renewable and biodegradable carbon sources, ADPGlc Ppaseis an attractive enzyme target for protein engineering. Understanding theregulation of the ADPGlc Ppase enzyme family is necessary for thebioengineering of the enzyme and could lead to rational protein engineeringof the enzyme to increase starch production