STRUCTURES AND DYNAMICS OF A DNA PROTEIN COMPLEX

DNA 蛋白质复合物的结构和动力学

• 批准号: 6240633
• 负责人: DON EDEN
• 金额: $ 23.73万
• 依托单位: SAN FRANCISCO STATE UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-01-01 至 1997-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6240633
• 关键词: DNA; DNA methylation; birefringences; cofactor; elasticity; enzyme complex; enzyme structure; lasers; light scattering; methyltransferase; molecular dynamics; nucleic acid structure; physical model; protein structure; solutions

The long range goal of this project is to develop an understanding of the interactions that occur between DNA and proteins in solution which result in the formation of highly specific complexes that perform a variety of specific functions. The project will focus on methyltransferases and their interaction with target DNA. Methylation performs many functions ranging from the protection of host DNA against bacterial restriction endonucleases to the regulation of gene expression in eukaryotes. The experiments are focused on one of the most characterized methyltransferases, EcoRI methyltransferase, which uses the cofactor S- adenosylmethionine to methylate the central adenine in the canonical site 5'GAATTC3'. There is considerable evidence that the structure of both the DNA and the methyltransferase are distorted when the complex is formed. The distortions are likely to add specificity to the formation of the complex. The nature of the distortions and the forces that are required to cause them have not been determined. The techniques of transient electric birefringence and optical Kerr effect will be used to characterize the mechanical and electrical properties of the methyltransferase and the DNA, separately and in a ternary complex with a cofactor analog. We will determine the changes in shape and mechanical stiffness of the methyltransferase upon the addition of cofactors. We will determine the angle of the putative bend that is induced in the DNA and the relative position of the methyltransferase. The results will be compared with those for other DNA-protein complexes with an aim of developing a physical model to explain the interactions in solution. The mechanical properties of the methyltransferase will be compared with other proteins of similar size that are believed to have elastic hinges between their domains.

本项目的长期目标是了解 DNA和蛋白质在溶液中发生的相互作用， 在形成高度特异性的复合物中， 具体功能。该项目将重点关注甲基转移酶及其 与靶DNA的相互作用。甲基化执行许多功能， 从保护宿主DNA免受细菌限制 核酸内切酶对真核生物中基因表达的调节。的 实验集中在一个最具特色的 甲基转移酶，EcoRI甲基转移酶，它使用辅因子S- 腺苷甲硫氨酸甲基化的中央腺嘌呤在典型的网站 5 'GAATTC 3'。有相当多的证据表明， 当复合物形成时，DNA和甲基转移酶被扭曲。 这些扭曲可能会增加形成的特异性， 复杂.扭曲的性质和所需的力量 因为他们还没有确定。 瞬态电双折射和光学克尔效应技术 将被用来表征机械和电气性能， 甲基转移酶和DNA，分别和三元复合物 与辅因子类似物。我们将确定形状的变化， 甲基转移酶的机械刚度在添加 辅因子我们将确定假定的弯曲的角度， 在DNA中诱导的甲基转移酶和甲基转移酶的相对位置。 并与其它DNA-蛋白质复合物的结果进行了比较 目的是建立一个物理模型来解释 溶液甲基转移酶的机械性质将是 与其他类似大小的蛋白质相比， 在它们的域之间有弹性铰链。