SAM核酸开关的结构与机理

项目名称： SAM核酸开关的结构与机理

项目编号： No.31300603

项目类型： 青年科学基金项目

立项/批准年度： 2014

项目学科： 生物科学

项目作者： 陆昌瑞

作者单位： 东华大学

项目金额： 25万元

中文摘要： 核酸开关是调控型非编码RNA。它们能直接感受环境变化，将信息传达至下游，调控基因表达。类似于蛋白调节子，它们通过结合生理代谢途径中的最终或中间产物，利用反馈机制完成调节表达。 S-腺苷基甲硫氨酸（SAM）核酸开关是数量最多、调节机理最多样的核糖开关。众多的SAM核酸开关结合SAM，通过终止转录，抑制转译等机制调节细菌基因表达。其中，SAM-IV和SAM-V核糖开关是最新成员。SAM-IV在放线菌体内控制SAM的代谢，而SAM-V则被发现存在于在很多海洋细菌体内。二者结合SAM后，可能都利用阻塞核糖体结合位点的机理调节下游基因表达，终止SAM合成。尽管它们的调节角色在各自母体内类似，SAM-IV和SAM-V核糖开关之间没有相似的序列，结构迥异，和SAM核酸开关中其他成员也不同源。 我们的研究小组利用X射线晶体学和化学探测法，分析SAM-IV和SAM-V核糖开关的结构、配体识别、构象的动态变

中文关键词： 核糖开关；结构功能；转录调控；化学探测；

英文摘要： Riboswitches are recently discovered regulatory RNAs that directly relay environmental cues to the genetic regulatory machinery. They are often involved in feedback mechanisms by binding small molecules that are either products or intermediates of the synthetic pathway, which was previously known to be exclusively performed by proteins. Riboswitches that bind to S- Adenosylmethionine (SAM) is the most common riboswitch both in terms of numbers and mechanisms of regulation. There are many SAM-responsive riboswitches that regulate bacterial gene expression at levels of transcription attenuation, translation inhibition and etc. Within this SAM riboswitch family, SAM-IV and SAM-V are the newest members of the SAM-riboswitch family. SAM-IV controls SAM metabolism in Actinomycetales, while SAM-V RNA are found in marine metagenomes. They both appear to regulate downstream gene expression by ribosome binding site occlusion by binding specifically to SAM, and feedback regulate the SAM biosynthetic pathway. However, these riboswitches share no sequence, structural or mechanistic homology with each other, sharing no phylogenetic connection with rest of the SAM riboswitch family, despite similar biological role they hold in their native environments. Our research group employs both X-ray crystallography and chemical probi

英文关键词： riboswitch；structure and function；transcription regulation；chemical probing；