Translational Control Coupled to Flagellum Assembly

与鞭毛组装耦合的平移控制

• 批准号: 7643246
• 负责人: KELLY T HUGHES
• 金额: $ 24.68万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-03-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7643246
• 关键词: 3' Untranslated Regions; 5' Untranslated Regions; Address; Affect; Amino Acids; Anabolism; Applications Grants; Area; Bacteria; Cells; Code; Complex; Coupled; Coupling; Data; Disease; Escherichia coli; Filament; Flagella; Flagellin; Foundations; Gene Expression; Gene Expression Regulation; Genes; Genetic Transcription; Genetic Translation; Goals; Growth; Individual; Lead; Mediating; Messenger RNA; Modeling; Molecular; Molecular Chaperones; N-terminal; Open Reading Frames; Organelles; Peptides; Post-Transcriptional Regulation; Process; Production; Protein Secretion; Proteins; RNA; RNA Binding; Regulation; Regulon; Reporting; Research; Rest; Role; Signal Transduction; Site; Solutions; Source; Structure; System; Transcriptional Regulation; Translating; Translations; Type III Secretion System Pathway; Untranslated RNA; Untranslated Regions; Virulence; Work; base; design; fliC gene product; inhibitor/antagonist; kinetosome; mRNA Stability; mutant; novel; pathogen; public health relevance; research study

DESCRIPTION (provided by applicant): Assembly of the bacterial flagellum requires the action of a specialized secretion apparatus at the base, which transports the needed proteins into a central channel in the structure that conducts them to their site of incorporation at the tip. The flagellar secretion machinery is closely related to the "injectisome" used by many gram-negative pathogens to inject effector proteins into host cells. In both the flagellar and nonflagellar systems this export mechanism is referred to as "type III" secretion. In type III systems gene regulation is coordinated with assembly. How is gene regulation coupled to assembly of large organelles such as the flagellum and the injectasome? Much information has been obtained about how transcription of genes in flagellar and virulence type III systems is coupled to assembly. Little is know about how translation is coupled to assembly of these structures. This proposal will examine the translational control of the flagellar filament protein. It is reported that secretion through the flagellar and injectisome structures can occur through mRNA signals. Addition of the 5' and 3' mRNA untranslated regions of the fliC flagellin is reported to target proteins for secretion through the flagellum. Data suggests that translation of the fliC gene is localized to the base of each flagellum. This would provide a mechanism to independently regulate gene expression for different flagella within an individual cell. This process will be a focus of the studies in this proposal. PUBLIC HEALTH RELEVANCE: A goal of my lab is to understand how flagellar gene expression is coupled to assembly. While much is known about how genes respond to levels of small metabolites, the construction of large organelles poses unique challenges and has offered unique solutions to the coordinated regulation of genes in building complex structures, such as the bacterial flagellum. We know a fair amount about how transcription of flagellar genes is coupled to assembly through the action of a transcriptional inhibitor (FlgM) that is removed at a particular point in flagellar assembly (secretion through a completed hook-basal body structure). A few years ago we observed that increased transcription of the fliC flagellin gene alone did not lead to increased flagellin protein, but the Kutsukake and Yamamoto labs reported that increased transcription of the entire flagellar regulon resulted in a 2- to 4-fold increase in the number of flagellar per cell [1]. This suggested that a mechanism inhibits flagellin post-transcription when it is not coupled to the rest of flagellar biosynthesis. More recent and intriguing work from the Westerlund-Wickstrvm lab reports that any heterologous protein can be secreted through the bacterial flagellum if its corresponding open reading frame is flanked by the 5' and 3'-untranslated regions from the E. coli fliC gene [2]. If true, this is remarkable because it suggests that a peptide secretion signal is not required for secretion through the flagellum and information in the untranslated RNA can target proteins for secretion. Whether secretion is directed by peptide or RNA signals is a long-standing area of controversy in the type III secretion field. Little has been done to characterize the role of translational control in coupling flagellar gene expression to assembly. We propose to address this level of control in this grant application.

描述（由申请人提供）：细菌鞭毛的组装需要在基部的专门分泌装置的作用，该设备将所需蛋白质传输到结构中的中心通道中，该蛋白将其导致其在尖端的掺入部位。鞭毛分泌机械与许多革兰氏阴性病原体使用的“注射体”密切相关，以将效应蛋白注入宿主细胞。在鞭毛和非鞭毛系统中，此出口机制被称为“ III型”分泌。在III型系统中，基因调节与组装协调。基因调节如何与大型细胞器（例如鞭毛和注射体）的组装结合？已经获得了有关鞭毛和毒力III型系统中基因的转录的很多信息。几乎不知道如何将翻译与这些结构的组装耦合。该建议将检查鞭毛细丝蛋白的翻译控制。据报道，通过鞭毛和注射体结构的分泌可以通过mRNA信号发生。据报道，Flic鞭毛蛋白的5'和3'mRNA未翻译区域通过鞭毛靶向蛋白质。数据表明，FLIC基因的翻译位于每个鞭毛的底部。这将提供一种机制，可以独立调节单个细胞内不同鞭毛的基因表达。该过程将是该提案中研究的重点。公共卫生相关性：我的实验室的目标是了解如何将鞭毛基因表达与组合结合在一起。尽管对基因对小型代谢产物的水平有何反应知之甚少，但大型细胞器的结构却带来了独特的挑战，并为建立复杂结构（例如细菌鞭毛）的基因协调调节提供了独特的解决方案。我们了解了一个相当多的知识，即如何通过转录抑制剂（FLGM）的作用将鞭毛基因的转录耦合到装配中，该转录抑制剂（FLGM）在鞭毛组装中的特定点（通过完整的挂钩 - 巴斯体体结构分泌）被删除。几年前，我们观察到，单独的鞭毛蛋白基因的转录增加并没有导致鞭毛蛋白蛋白增加，但是库特苏克蛋白和Yamamoto Labs报告说，整个鞭毛调节的转录增加导致每个细胞的鞭毛数量增加2至4倍[1]。这表明一种机制在未与其他鞭毛生物合成偶联时会抑制转录后的鞭毛蛋白。 Westerlund-Wickstrvm实验室的最新和有趣的工作报告说，如果将其相应的开放式阅读框架侧翼是来自大肠杆菌基因的5'和3'-非翻译区域的侧面，则可以通过细菌鞭毛分泌任何异源蛋白[2]。如果是真的，这是显着的，因为它表明通过鞭毛分泌不需要肽分泌信号，而未翻译的RNA中的信息可以靶向蛋白质进行分泌。分泌是由肽或RNA信号指导的是III型分泌领域中的长期争议。几乎没有做到表征翻译控制在耦合鞭毛基因表达与组装中的作用。我们建议在本赠款应用程序中解决此级别的控制级别。