The Spatial and Temporal Integration of Chromosome Segregation and Cytokinesis

描述(由申请人提供)：细胞周期的进展需要DNA复制启动和必须以时间和空间特定的方式发生的多个事件之间的精细协调。参与复制启动的蛋白质在真核生物和原核生物中非常相似。数十年的研究详细揭示了这些蛋白质是如何启动复制的。然而，越来越明显的是，这些蛋白质也介导了非复制功能。关于这些功能如何与染色体复制相协调，人们知之甚少。这项建议的目标是定义在新月弯杆菌中整合多种细胞周期功能的机制，特别是专注于负责复制起始的细菌蛋白DNAA。由于其单条染色体的同时复制和极向分离以及细胞的不对称分裂，它是研究细菌细胞周期调控电路的理想模型。最近，一个Dna A突变体被发现，它破坏了染色体复制的协调和胞质分裂的空间/时间控制。这项建议的具体目的是确定DNAA在调节(A)早期分裂部位的类核堵塞和(B)利用高分辨率成像结合具有特定荧光标记的工程菌株和关键的细胞分裂蛋白耗尽来协调染色体分离和分裂部位选择方面的作用。 公共卫生相关性：细胞分裂需要对细胞周期进程中涉及的多个事件进行精细的协调。在人类中，这些事件的错误协调可能会导致致命的发育缺陷，包括癌症。对细菌用来完成这种精致协调的机制的清楚了解，可以揭示包括人类在内的各种进化有机体使用的共同方案。

DESCRIPTION (provided by applicant): Progression through the cell cycle requires exquisite coordination between DNA replication initiation and the multiple events that must take place in a timely and spatially-specific manner. Proteins involved in replication initiation are remarkably similar in eukaryotes and prokaryotes. Decades of research revealed in fine detail how these proteins function to initiate replication. However, it is becoming increasingly apparent that these proteins also mediate non-replication functions. Little is known about how these functions are coordinated with chromosome replication. The goal of this proposal is to define the mechanisms that integrate multiple cell cycle functions in Caulobacter crescentus, specifically focusing on the bacterial protein responsible for replication initiation, DnaA. Caulobacter is an ideal model for studying bacterial cell cycle regulatory circuitry due to the simultaneous replication and polar segregation of its single chromosome and its asymmetric cell division. Recently, a dnaA mutant that disrupts the coordination of chromosome replication and spatial/temporal control of cytokinesis was identified. The specific aims of this proposal are to determine the role of DnaA in mediating (a) nucleoid occlusion at the incipient division site and (b) the coordination of chromosomal segregation with division site selection using high-resolution imaging combined with engineered strains with specific fluorescent tags and key cell division protein depletions. PUBLIC HEALTH RELEVANCE: Cell division entails exquisite coordination of multiple events involved in cell cycle progression. In human, erroneous coordination of these events can cause fatal developmental defects including cancer. A clear understanding of the mechanisms used by bacteria to accomplish such exquisite coordination can reveal common schemes used across evolutionary diverse organisms, including human.