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

原核生物复制、细胞周期、基因表达和水平基因转移的机制和调控，重点关注枯草芽孢杆菌。

• 批准号: 10552390
• 负责人: ALAN D GROSSMAN
• 金额: $ 74.93万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2027-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10552390
• 关键词: Affect; Antibiotic Resistance; Bacillus subtilis; Bacteria; Bacterial Genome; Bacteriophages; Biology; Cell Cycle; Cell physiology; Cells; Cellular Stress; Chromosomes; DNA biosynthesis; Development; Elements; Environment; Event; Evolution; Frequencies; Gene Expression; Gene Transfer; Genes; Genome; Gram-Positive Bacteria; Growth; Horizontal Gene Transfer; Human Microbiome; Life Cycle Stages; Mediating; Metabolic; Mobile Genetic Elements; Phenotype; Plasmids; Population; Prevalence; Process; Prokaryotic Cells; Regulation; Selfish DNA; Skin; Symbiosis; Tetracycline Resistance; Virulence; Virus; Visualization; Work; biological adaptation to stress; driving force; fitness; interest; microbial; pathogenic bacteria; response; trait

Project Summary/Abstract Horizontal gene transfer (HGT) is a driving force in microbial evolution. It is largely mediated by mobile genetic elements, including viruses, conjugative plasmids, and integrative and conjugative elements (ICEs; aka conjugative transposons), and many bacterial genomes contain several mobile genetic elements, including ICEs and temperate phages. Conjugative elements are well known agents that contribute to the spread of genes for antibiotic resistances, virulence, symbiosis, metabolic functions, and more. ICEs were first discovered because they confer some of these phenotypes. However, potential phenotypes conferred to bacteria by the vast majority of ICEs are not known. Our recent work indicates that ICEs confer beneficial phenotypes that extend well beyond those of some of the previously characterized ICEs, and that some of these phenotypes involve functional interactions between ICEs and bacterial viruses. We are focusing on mechanisms controlling horizontal gene transfer, interactions between mobile genetic elements and their host cells, and the interplay between different mobile elements found in the same cell. Many of our studies are initiated in the bacterium Bacillus subtilis. It is easy to grow and manipulate, naturally contains a variety of mobile elements, including one ICE (ICEBs1) and one functional (SPß) and two defective (PBSX, skin) temperate phages, together comprising almost 6% of the genome. Our recent work indicates that there are beneficial phenotypes conferred by ICEBs1 to host cells that extend well beyond those conferred by previously characterized ICEs, including effects on the timing of sporulation and the activity of other resident elements. Despite the prevalence and importance of ICEs, there are major deficiencies in our understanding of these elements, especially in Gram positive bacteria. Notably, little is known about the interactions between ICEs and their host cells including with co-resident viruses, and the effects ICEs have on fitness of their bacterial hosts. Furthermore, little is known about the interactions between functions encoded by ICEs and those encoded by hosts, and how these interactions influence and determine the host range and efficiencies with which ICEs function in different species. Our work will continue to focus on the lifecycle of ICEBs1 and Tn916, an ICE that is naturally found in several bacterial pathogens and is involved in the spread of tetracycline resistance between them. The ability to experimentally induce ICEBs1 in ~25- 90% of cells in a population, to achieve relatively high conjugation frequencies, and to visualize events in single cells has allowed us to answer previously difficult or unstudied problems fundamental to the ICE lifecycle. Our expertise in chromosome dynamics, DNA replication, stress responses, and microbial development dovetails nicely with our studies of ICEs and phages, notably how these processes affect the lifecycles of mobile genetic elements and how mobile genetic elements affect these processes. We plan to pursue these interests, with particular focus on the connections between ICEs, phages, and cellular processes. Our findings should be relevant to the biology of many bacterial species, especially regarding the transfer of genes between bacteria growing in different environments, including the human microbiome.

项目总结/摘要 水平基因转移（Horizontal gene transfer，HGT）是微生物进化的重要驱动力。它在很大程度上是由移动的遗传 元件，包括病毒、接合质粒、整合和接合元件（ICE; aka conjugative 转座子），并且许多细菌基因组含有几个移动的遗传元件，包括ICE和温带细菌。 接合元件是公知的因子，其有助于抗生素抗性、毒力、 共生、代谢功能等等。ICE最初被发现是因为它们赋予了这些表型中的一些。 然而，绝大多数ICE赋予细菌的潜在表型尚不清楚。我们最近的工作 表明ICE赋予的有益表型远远超出了一些先前表征的表型， 这些表型中的一些涉及ICE和细菌病毒之间的功能相互作用。 我们的重点是控制水平基因转移的机制，移动的遗传元件之间的相互作用 和它们的宿主细胞，以及在同一细胞中发现的不同移动的元素之间的相互作用。我们的许多研究都是 由枯草芽孢杆菌引发。它易于生长和操纵，自然包含了各种移动的 元件，包括一个ICE（ICEBs 1）和一个功能性（SPE 2）和两个缺陷性（PBSX，皮肤）温带， 占基因组的6%我们最近的工作表明，有有益的表型赋予 ICEBs 1对宿主细胞的作用远远超出了先前表征的ICE所赋予的作用，包括对 孢子形成的时间和其他驻留元素的活动。 尽管ICE的普遍性和重要性，但我们对这些元素的理解存在重大缺陷， 尤其是革兰氏阳性菌。值得注意的是，对ICE与其宿主细胞之间的相互作用知之甚少 包括与共存的病毒，以及ICE对其细菌宿主的适应性的影响。此外， 了解由ICE编码的功能与由主机编码的功能之间的相互作用，以及这些相互作用是如何发生的。 影响并决定了ICE在不同物种中发挥作用的宿主范围和效率。我们的工作将 继续关注ICEBs 1和Tn 916的生命周期，Tn 916是一种天然存在于多种细菌病原体中的ICE， 参与了它们之间四环素耐药性的传播。实验诱导ICEBs的能力1在~25- 群体中90%的细胞，以实现相对高的缀合频率，并可视化单细胞中的事件， 使我们能够回答以前困难的或未研究的问题，基本的ICE生命周期。我们的专业知识 染色体动力学、DNA复制、应激反应和微生物发育与我们的研究很好地吻合， ICEs和ICEs，特别是这些过程如何影响移动的遗传因子的生命周期，以及移动的遗传因子如何 影响这些进程的因素。我们计划追求这些利益，特别关注ICE之间的联系， 以及细胞过程。我们的发现应该与许多细菌物种的生物学有关，特别是 关于在不同环境中生长的细菌之间的基因转移，包括人类微生物组。