Mechanisms and regulation of replication, the cell cycle, gene expression, and horizontal gene transfer in prokaryotes, focusing on Bacillus subtilis

我们的长期目标是了解许多基本的分子机制和调控 细菌的细胞过程。我们特别感兴趣的是DNA复制的控制， 对复制、环境感知和信号转导中扰动的反应，以及机制 控制水平基因转移。我们选择这些研究的微生物是革兰氏阳性菌 枯草芽孢杆菌。关于B的信息非常丰富。枯草杆菌。它很容易种植和基因操纵 并且与实验上不易处理的几种病原体和环境细菌有关。 水平基因转移（Horizontal gene transfer，HGT）是微生物进化的驱动力。它主要是由移动的 遗传元件，包括病毒、接合质粒，以及整合和接合元件（ICE， 也称为接合转座子）。缀合元件是有助于免疫应答的公知试剂。 抗生素抗性、致病、共生、代谢等基因的传播。 尽管ICE的普遍性和重要性，但我们对这些问题的理解仍然存在不足。 元素，尤其是革兰氏阳性菌。我们的工作将集中在B中ICEB 1的生命周期上。枯草杆菌。的 在群体中>90%的细胞中实验诱导ICEBs 1并实现相对高的缀合的能力 频率将使我们能够回答以前困难或未研究的问题，对ICE生命周期至关重要。 我们还将鉴定和分析ICE功能所需的宿主基因，并研究ICE与 小区中的其他移动的元件。我们将把我们的分析扩展到Tn 916，这是一种广泛存在的ICE， 四环素耐药性我们的研究结果应该与生长在不同环境中的细菌之间的基因转移有关。 许多不同的环境，包括人类微生物组。 我们的工作也将集中在染色体动力学和基因表达的几个方面。细胞具有 调节复制起始的多种机制。细胞也有调节反应， 复制中的扰动，通常称为检查点，控制基因表达和细胞周期进程。 将基因表达和细胞周期进程与染色体复制和完整性相结合有助于防止细胞周期的变化。 产生具有缺陷染色体的细胞。基因组复制与细胞周期的协调 进展对于细胞分化和防止不受控制的细胞生长是重要的。微生物 发病机理通常取决于宿主中正常的细菌复制和生长。 我们将使用各种体内和体外的方法和方法来表征： 复制起始的控制;复制起始和转录因子DnaA的调节因子;和基因 在复制过程中受到干扰而受到控制。理解B中的这些过程。枯草将提供 关于各种生物中类似过程和同源蛋白质的见解，包括许多 革兰氏阳性病原体。

Our long term goals are to understand many of the molecular mechanisms and regulation underlying basic cellular processes in bacteria. We are particularly interested in the control of DNA replication, cellular responses to perturbations in replication, environmental sensing and signal transduction, and mechanisms controlling horizontal gene transfer. Our organism of choice for these studies is the Gram positive bacterium Bacillus subtilis. There is a wealth of information about B. subtilis. It is easy to grow and manipulate genetically and is related to several pathogens and environmental bacteria that are less tractable experimentally. Horizontal gene transfer (HGT) is the driving force in microbial evolution. It is largely mediated by mobile genetic elements, including viruses, conjugative plasmids, and integrative and conjugative elements (ICEs, also known as conjugative transposons). Conjugative elements are well known agents contributing to the spread of genes for antibiotic resistances, pathogenesis, symbiosis, metabolism, and more. Despite the prevalence and importance of ICEs, there are deficiencies in our understanding of these elements, especially in Gram positive bacteria. Our work will focus on the lifecycle of ICEBs1 in B. subtilis. The ability to experimentally induce ICEBs1 in >90% of cells in a population and achieve relatively high conjugation frequencies will allow us to answer previously difficult or unstudied problems fundamental to the ICE lifecycle. We will also identify and analyze host genes needed for ICE function and study interactions between ICEs and other mobile elements in cells. We will extend our analyses to Tn916, a widespread ICE involved in the spread of tetracycline resistance. Our findings should be relevant to the transfer of genes between bacteria growing in many different environments, including the human microbiome. Our work will also focus on several aspects of chromosome dynamics and gene expression. Cells have multiple mechanisms for regulating the initiation of replication. Cells also have regulatory responses to perturbations in replication, often called checkpoints, which control gene expression and cell cycle progression. Coupling gene expression and cell cycle progression to chromosome replication and integrity helps prevent the generation of cells with defective chromosomes. The coordination of genome duplication with cell cycle progression is important for cellular differentiation and preventing uncontrolled cell growth. Microbial pathogenesis often depends on normal bacterial replication and growth in the host. We will use a variety of approaches and methodologies, both in vivo and in vitro, to characterize: the control of replication initiation; regulators of the replication initiator and transcription factor DnaA; and genes controlled in response to perturbations in replication. Understanding these processes in B. subtilis will provide insights regarding similar processes and homologous proteins in a wide variety of organisms, including many Gram positive pathogens.