Genetic Control of Growth on Surfaces

副溶血性弧菌适应于表面的集体生活。当生长在表面或粘性层时，生物体诱导出一个大的基因系统，并分化成一个群集细胞。向群细胞的分化允许在表面和粘性环境中移动。细胞相互识别，运动在本质上是协调的或社会性的，导致复杂的多细胞行为和有组织的社区生长。蜂群细胞很好地移动和殖民表面：它被拉长和过度鞭毛。这项工作的重点是解开参与表面适应生活方式的调节网络，以便深入了解细菌如何在表面形成和维持群落。假设是不同的基因组在这些群体的发展过程中被开启和关闭。一个大的集合，编码外侧鞭毛运动系统，是已知的。第一个目标是识别由表面生长诱导的基因；设计了一种新的转座子和传递系统来实现对表面诱导基因的搜索。完成这一目标将导致鉴定与外侧鞭毛等级有关的基因，该基因尚未被系统地解剖，以及与运动无关但与表面适应生活方式相关的新基因。全面了解表面附着细菌的基因活性（基因身份和表达时间）；这可能会揭示相互连接的调节回路的存在，以协调基因表达。第二个目标集中在最近发现的一个潜在电路上。两个连接操纵子的突变导致群集细胞基因的不可诱导表达。一个操纵子（膜）编码一个缘状的伴侣-引导对和可能与外膜相关的蛋白质。第二个操纵子（fli）编码一种ABC周质型结合蛋白（类似于大肠杆菌fly）和一种类似于ggdef型传感器家族中许多蛋白质的产物。这些基因集与群集细胞分化之间的相互作用将通过使用诱变、过表达和蛋白质定位实验的组合来剖析。这些研究应该定义与表面生长相关的基因活性，并追踪使细菌能够在表面上建立生长和发展群落的调控电路网络。了解表面诱导的基因表达模式将揭示细菌如何适应环境、协调行为和发展结构群落或生物膜的重要原理。此外，该项目将对弧菌的遗传分析，特别是转座子突变和表面控制基因的全基因组搜索产生重大的教育影响，将被用作本科和研究生水平的教学工具。

V. parahaemolyticus is adapted to communal life on surfaces. When grown on a surface or in a viscous layer, the organism induces a large gene system and differentiates into a swarmer cell. Differentiation to the swarmer cell allows movement over surfaces and through viscous environments. Cells recognize each other, and movement is coordinated or social in nature, resulting in complex multicellular behavior and growth in organized communities. The swarmer cell is well-equipped to move over and colonize surfaces: it is elongated and hyperflagellated. The focus of this work is to unravel the regulatory networks that participate in the surface-adapted lifestyle in order to gain insight into how bacteria form and maintain communities on surfaces. The hypothesis is that different gene sets are turned on and off during the development of these communities. One large set, encoding the lateral flagellar motility system, is known. The first aim will be to identify genes induced by growth on surfaces; a novel transposon and delivery system has been designed to implement search for surface-induced genes. Completion of this aim will result in the identification of genes involved in the lateral flagellar hierarchy, which has not been systematically dissected, and new genes not required for motility but pertinent to the surface-adapted lifestyle. A comprehensive picture of gene activity (gene identity and timing of expression) of surface-attached bacteria will be developed; this will likely reveal the existence of interconnecting regulatory circuits to coordinate gene expression. The second aim focuses on one potential circuit that has recently been discovered. Mutations in two linked operons cause uninducible expression of swarmer cell genes. One operon (fim) encodes a fimbrial-like chaperone-usher pair and proteins that may be outer-membrane associated. The second operon (fli) encodes an ABC periplasmic-type binding protein (similar to Escherichia coli FliY) and a product that resembles a number of proteins in the GGDEF-type sensor family. The interactions between these gene sets and swarmer cell differentiation will be dissected by using a combination of mutagenesis, overexpression, and protein localization experiments. These studies should define gene activity pertinent to growth on surfaces and trace the network of regulatory circuitry that enables bacteria to establish growth and develop communities on surfaces. Understanding the pattern of surface-induced gene expression should reveal important principles about how bacteria adapt to their environment, coordinate behavior, and develop structured communities or biofilms. Moreover, this project will have significant educational impact for genetic analysis in Vibrio, specifically transposon mutagenesis and the genome-wide search for surface-controlled genes, will be used as an undergraduate and graduate level teaching tool.