Molecular Genetics of Biofilm Formation

描述（由申请人提供）：表面相关细菌群体被称为生物膜。广泛认识到，生物膜影响无数的环境，从水管留置装置在医院的病人，导致了越来越多的兴趣，调查的分子机制的形成和维持这些社区。一个共同的特点出现在所有的生物膜，已经分析到目前为止：组成细胞举行在一起的细胞外基质。因此，无论考虑的物种，一个中心假设出现：生物膜形成是一个发育过程，其中细菌经历了一个受调节的生活方式转换，从游牧的单细胞状态到定居的多细胞状态，其中不同的细胞类型共存，并在空间和时间上组织作为细胞外基质生产的结果。本文提出的实验代表了我们继续努力，使用芽孢杆菌枯草芽孢杆菌严格测试这一中心假设的各个方面。通过遗传和生物化学方法的结合，我们已经确定了一个关键的信号转导途径，该途径控制着从单细胞到不同细胞类型共存的基质封闭群落的转变。在生物膜诱导条件下，细胞亚群开始分泌环脂肽表面活性素。表面活性素作为一种发育信号作用于不同的细胞亚群--我们称之为旁分泌信号传导--诱导它们转录参与制造基质的基因。通过生产的矩阵的社会发展高度的时空组织最终孢子形成优先发生在顶部的生物膜。进入孢子形成受到严格调控-存在发育检查点，由此孢子形成被延迟，直到细胞外基质的合成完成。继续采取生物化学和分子遗传学方法相结合的方法，我们建议：（1）表征基质的蛋白质组分，（2）定义负责发育检查点的机制，（3）确定表面活性素依赖性信号转导途径的分子机制。 公共卫生相关性：细菌非常善于在一个被称为生物膜形成的过程中在表面上定居。当生物膜在错误的表面上形成时，例如在开放性伤口或植入的医疗设备上，它们可能会导致非常难以根除的慢性感染。通过研究细菌如何形成生物膜的分子细节，我们可以设计出干扰这一过程的策略;这些策略最终可以用于开发抗生物膜剂来治疗感染。

DESCRIPTION (provided by applicant): Populations of surface-associated bacteria are known as biofilms. The widespread recognition that biofilms impact myriad environments, from water pipes to indwelling devices in hospital patients, has led to an increased interest in investigating the molecular mechanisms underlying the formation and maintenance of these communities. A common feature emerges from all biofilms that have been analyzed to date: the constituent cells are held together by an extracellular matrix. Thus, regardless of the species under consideration, a central hypothesis emerges: Biofilm formation is a developmental process in which bacteria undergo a regulated lifestyle switch from a nomadic unicellular state to a sedentary multicellular state where different cell types co-exist and are spatially and temporally organized as a consequence of extracellular matrix production. The experiments proposed herein represent our continued efforts to critically test aspects of this central hypothesis using the sporulating bacterium Bacillus subtilis. Through a combination of genetic and biochemical approaches we have identified a key signal transduction pathway that governs the transition from single cells to matrix-enclosed communities where different cell types co-exist. Under biofilm-inducing conditions a subpopulation of cells begins to secrete the cyclic lipopeptide surfactin. Surfactin serves as a developmental signal that acts on a different subpopulation of cells - a process we refer to as paracrine signaling - inducing them to transcribe the genes involved in making the matrix. Through the production of the matrix the community develops a high degree of spatio-temporal organization culminating with sporulation occurring preferentially at the top of the biofilm. Entry into sporulation is tightly regulated - there is a developmental checkpoint whereby sporulation is delayed until the synthesis of the extracellular matrix is complete. Continuing to takes approaches that blend biochemical and molecular genetic methodologies we propose to: (1) characterize the protein component of the matrix, (2) define the mechanism responsible for the developmental checkpoint, and (3) determine the molecular mechanism of the surfactin-dependent signal transduction pathway. PUBLIC HEALTH RELEVANCE: Bacteria are remarkably adept at colonizing surfaces in a process known as biofilm formation. When biofilms form on the wrong surfaces, such as on open wounds or on implanted medical devices, they can cause chronic infections that are extremely difficult to erradicate. By studying the molecular details of how bacteria form biofilms we can devise strategies to interfere with the process; these could eventually be used to develop anti-biofilm agents to treat infections.