Molecular mechanisms regulating cell cycle progression in Caulobacter crescentus

新月柄杆菌细胞周期进程的分子机制

• 批准号: 7613616
• 负责人: Lisa M. Bowers
• 金额: $ 4.72万
• 依托单位: UNIVERSITY OF CALIFORNIA BERKELEY
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-01-01 至 2010-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7613616
• 关键词: Agriculture; Anti-Bacterial Agents; Antibiotics; Antibodies; Aspartate; Bacteria; Bacteriophages; Binding; Bioinformatics; Biological Models; Biological Warfare; Biology; Biomedical Engineering; Biosensing Techniques; Caulobacter; Caulobacter crescentus; Cell Cycle; Cell Cycle Progression; Cell Cycle Regulation; Cell Survival; Cell division; Cells; Cellular biology; Chimeric Proteins; Complex; Comprehension; Coupled; DNA biosynthesis; Defect; Drug Delivery Systems; Essential Genes; Eukaryotic Cell; Flagella; Genes; Genetic; Genetic Transcription; Genome; Hand; Histidine; Hybrids; In Vitro; Label; Life; Life Cycle Stages; Location; Logic; Molecular; Monitor; Morphology; Mutation; Names; Orthologous Gene; Pathway interactions; Phenotype; Phosphoric Monoester Hydrolases; Phosphorylation; Phosphotransferases; Physiologic pulse; Prokaryotic Cells; Property; Proteins; Proteobacteria; Reaction; Replication Origin; Role; Shapes; Signal Transduction; Site; Source; Surface; Time; Water; Work; cell motility; chromosome replication; daughter cell; drug discovery; in vivo; insight; loss of function; mutant; promoter; protein-histidine kinase; public health relevance; reconstitution; response; small molecule; transcription factor

DESCRIPTION (provided by applicant): A fundamental question in biology is how one cell divides to yield two progeny with different identities. Like eukaryotic cells, bacteria undergo complex life cycles and often produce daughter cells with distinct shapes and properties. In this work, Caulobacter crescentus is used as a model system for the study of asymmetry coupled to the division cycle. In this bacterium, each division produces two morphologically distinct daughter cells, a non-motile cell with a stalk that attaches to surfaces and a motile swarmer cell with a flagellum that propels it through the water. The stalked cell immediately begins a new round of chromosome replication and division, but the swarmer cell is unable to initiate DMA replication until it differentiates into a stalked cell. This complex cell division cycle is orchestrated by a network of two-component signal transduction proteins. The response regulator CtrA is a transcription factor that controls the expression of many cell cycle- regulated genes but also blocks DNA replication by binding to the origin of replication. CtrA activity is required for cell viability but it must be temporarily eliminated in stalked cells to permit the initiation of chromosome replication. CtrA activity is indirectly opposed by the essential response regulator DivK. Phosphorylated DivK results in a decrease in CtrA activity, which ultimately allows chromosome replication in the stalked cell. Thus, phosphorylation of DivK is essential for viability. DivK is known to be activated by the histidine kinase (HK) DivJ but because DivJ is dispensible, DivK must be phosphorylated by another HK or small molecule phosphodonor in Caulobacter. We propose a whole-genome approach to identify other HKs that could participate in DivK phosphorylation. Specifically, we aim to delete the gene for each of the 59 non-essential HKs in combination with a divJ deletion. This approach has yielded a likely candidate which we have tentatively named DivM other candidates must still be ruled out. We also aim to characterize the terminal phenotype of cells lacking both DivJ and DivM, determine the location and activity of DivM during the cell cycle, and elucidate the phosphorylation pathway from DivM to DivK. PUBLIC HEALTH RELEVANCE: The work proposed here is integral to achieving a complete understanding of the regulatory cascade leading to cell-cycle progression and differentiation in Caulobacter. Comprehension of the regulatory cascade could have far-reaching implications because many of the mechanisms discovered in Caulobacter are conserved among other species with important roles in agriculture, biowarfare, biosensing, and bioengineering. In addition, elucidating the basic mechanisms involved in bacterial cell cycle progression will generate key insights into prokaryotic cell biology, which will in turn help to identify new targets for antibacterial drug discovery.

描述（由申请人提供）：生物学中的一个基本问题是一个细胞如何产生两个具有不同身份的后代。像真核细胞一样，细菌经历复杂的生命周期，并且经常产生具有不同形状和特性的子细胞。在这项工作中，花椰菜新月形被用作模型系统，用于研究与分裂周期的不对称性研究。在该细菌中，每个分裂都会产生两个形态上不同的子细胞，一种非振动细胞，带有茎，附着在表面上，一个带有鞭毛的运动蜂窝细胞将其推向水中。缠扰的细胞立即开始了新的一轮染色体复制和分裂，但是堆积细胞无法启动DMA复制，直到将其区分成茎细胞为止。这种复杂的细胞分裂周期由两组分组信号转导蛋白的网络策划。响应调节剂CTRA是一个转录因子，可控制许多细胞周期调控基因的表达，但也通过与复制的起源结合来阻断DNA复制。细胞活力需要CTRA活性，但必须在茎细胞中暂时消除，以允许染色体复制的开始。 CTRA活性与基本响应调节器Divk间接相对。磷酸化的DIVK导致CTRA活性的降低，这最终允许在茎细胞中复制染色体。因此，DIVK的磷酸化对于生存力至关重要。已知DIVK被组氨酸激酶（HK）DivJ激活，但由于DIVJ是可分配的，因此必须通过花椰菜中的另一种HK或小分子磷酸磷酸化DIVK磷酸化。我们提出了一种全基因组方法，以识别可能参与DIVK磷酸化的其他HK。具体而言，我们旨在删除59个非必需的HK中的每个基因与DIVJ缺失结合使用。这种方法产生了一个可能的候选人，我们暂时命名了其他候选人，必须排除其他候选人。我们还旨在表征缺乏DIVJ和DIVM的细胞的末端表型，确定DIVM在细胞周期中的位置和活性，并阐明从DIVM到Divk的磷酸化途径。公共卫生相关性：此处提出的工作是对导致细胞周期进展和分化Caulobacter的监管级联反应的完全理解的重要组成部分。对监管级联的理解可能具有深远的影响，因为在花椰菜中发现的许多机制都是在其他在农业，生物果实，生物传感和生物工程中起作用的物种中保守的。此外，阐明细菌细胞周期进程中涉及的基本机制将产生对原核生物细胞生物学的关键见解，这反过来又有助于确定抗菌药物发现的新靶标。