Cell Cycle Regulation in Caulobacter Crescentus

新月柄杆菌的细胞周期调控

• 批准号: 8503797
• 负责人: Michael Laub
• 金额: $ 29.07万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-04-01 至 2017-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8503797
• 关键词: ATP Hydrolysis; Activity Cycles; Alphaproteobacteria; Antibiotics; Bacteria; Bacterial Proteins; Binding; Biochemical; Bioinformatics; Biological; Biological Assay; Biological Models; Biology; Caulobacter; Caulobacter crescentus; Cell Cycle; Cell Cycle Progression; Cell Cycle Regulation; Cell Polarity; Cell division; Cells; ChIP-seq; Complex; Coupled; Coupling; DNA biosynthesis; Daughter; Development; Drug Targeting; Ensure; Eukaryota; G1 Phase; G2 Phase; Generations; Genes; Genetic; Genetic Screening; Genomics; Glucose; Goals; Growth; Heart; Light; Link; Maps; Messenger RNA; Modeling; Molecular; Molecular Chaperones; Mutation; Nucleotides; Nutrient; Organism; Periodicity; Proteins; Regulation; Replication Initiation; Replication Origin; Role; S Phase; Signal Pathway; Signal Transduction; Signaling Protein; Starvation; System; Testing; Trans-Activators; Translating; Translations; Work; base; cell growth; daughter cell; design; genetic regulatory protein; in vitro Assay; in vivo; insight; pathogen; public health relevance; response; transcription factor

DESCRIPTION (provided by applicant): Proper spatial and temporal regulation of the cell cycle is crucial to the survival and proliferation of all organisms. Complex regulatory circuits have evolved to ensure stable, orderly progression through the cell cycle. Surprisingly, the molecular mechanisms and design principles underlying these circuits remain incompletely understood, particularly in bacteria. The alpha-proteobacterium Caulobacter crescentus is an experimentally tractable system for elucidating the fundamental mechanisms underlying cell cycle regulation in bacteria, and for understanding regulation at the systems level. The Caulobacter cell cycle is driven largely by two essential regulators: CtrA and DnaA. CtrA is a response regulator and two-component signal transduction protein that directly regulates the expression of nearly 100 genes, many of which coordinate cell division. CtrA also directly binds to and silences the origin of replication in daughter swarmer cells, but is inactivated and degraded in daughter stalked cells. CtrA thus governs the asymmetric replicative fates of daughter cells, a hallmark of the Caulobacter cell cycle. However, CtrA does not significantly influence the fundamental periodicity of DNA replication. Instead, DnaA, a nearly universal bacterial protein that initiates DNA replication, governs the periodicity of replication. In rich media, DnaA protein levels are constant, indicating that it is regulated predominantly at the level of activity. Although substantial progress has been made in understanding the regulation of CtrA and, to a lesser extent, DnaA, major gaps remain. The goal of this project is to define the complete molecular circuitry controlling CtrA and DnaA in both nutrient replete conditions and following starvation. We aim to identify new components of this circuitry, to elucidate their connections to DnaA and CtrA, and to understand their dynamics using a combination of genetic, biochemical, bioinformatic, genomic, and cell biological approaches. Specifically, we aim to (i) determine how the activation of CtrA is coupled to DNA replication initiation, (ii) idenify and characterize factors that regulate DnaA activity during growth in rich media, and (iii) elucidate the molecular mechanisms governing CtrA and DnaA activity following nutrient starvation. These studies will unveil how bacterial cells tightly regulate DNA replication and modulate cell cycle progression in a range of growth conditions. A better understanding of how bacteria regulate their cell cycle will guide the development of new antibiotics that slow or halt the proliferation of pathogens. Finally, by comparing the regulatory strategies unveiled here to those employed in eukaryotes our work will help to reveal the design principles of regulatory circuits throughout biology.

描述（由申请人提供）：细胞周期的适当空间和时间调节对所有生物体的存活和增殖至关重要。复杂的调节回路已经进化，以确保细胞周期的稳定，有序的进展。令人惊讶的是，这些电路背后的分子机制和设计原理仍然不完全清楚，特别是在细菌中。α-变形杆菌Caulobacter crescentus是一种实验上易于处理的系统，用于阐明细菌细胞周期调控的基本机制，并用于理解系统水平的调控。柄杆菌属细胞周期主要由两种基本调节剂驱动：CtrA和DnaA。CtrA是一种反应调节因子和双组分信号转导蛋白，直接调节近100个基因的表达，其中许多基因协调细胞分裂。CtrA还直接结合到子群体细胞中的复制起点并使其沉默，但在子茎细胞中失活并降解。因此，CtrA控制子细胞的不对称复制命运，这是柄杆菌属细胞周期的标志。然而，CtrA并不显著影响DNA复制的基本周期性。相反，DnaA，一种几乎通用的启动DNA复制的细菌蛋白质，控制着复制的周期性。在丰富的培养基中，DnaA蛋白水平是恒定的，表明它主要在以下水平上受到调节： 的活动。虽然在理解CtrA的调节方面取得了实质性进展，在较小程度上，DnaA，但仍然存在重大差距。该项目的目标是确定在营养充足的条件下和饥饿后控制CtrA和DnaA的完整分子电路。我们的目标是确定这个电路的新组件，阐明它们与DnaA和CtrA的联系，并使用遗传，生物化学，生物信息学，基因组学和细胞生物学方法的组合来了解它们的动态。具体而言，我们的目标是（i）确定如何激活CtrA耦合到DNA复制启动，（ii）阐明和表征的因素，在丰富的培养基生长过程中调节DnaA的活性，和（iii）阐明营养饥饿后的CtrA和DnaA活性的分子机制。这些研究将揭示细菌细胞如何在一系列生长条件下严格调节DNA复制和调节细胞周期进程。更好地了解细菌如何调节其细胞周期将指导新抗生素的开发，以减缓或阻止病原体的增殖。最后，通过比较在真核生物中使用的调控策略，我们的工作将有助于揭示整个生物学中调控回路的设计原则。