Phage Lysis

噬菌体裂解

• 批准号: 10631067
• 负责人: RYLAND F YOUNG
• 金额: $ 40.02万
• 依托单位: TEXAS A&M AGRILIFE RESEARCH
• 依托单位国家: 美国
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-05-01 至 2025-04-30
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10631067
• 关键词: Anabolism; Antibiotics; Antimicrobial Cationic Peptides; Area; Autolysis; Bacteria; Bacterial Infections; Bacteriophages; Binding; Bioinformatics; Biophysics; Cell Wall; Cells; Complex; Cytolysis; Enzymes; Event; Functional disorder; Genes; Genetic; Genomics; Homeostasis; In Vitro; Infection; Licensing; Lipids; Mammalian Cell; Membrane; Membrane Fusion; Membrane Proteins; Metagenomics; Modeling; Molecular; Multi-Drug Resistance; Nucleic Acids; Pathway interactions; Peptidoglycan; Phenotype; Process; Proteins; Single-Stranded DNA; System; Testing; Virus; clinically relevant; design; ds-DNA; endolysin; mutant; programs; tool

Lysis of the host cell by bacteriophage is, as the most frequent cytocidal event in the biosphere, a truly fundamental process. In addition, understanding the molecular basis of phage lysis is now clinically relevant because phage therapy is emerging as an important tool against multi-drug resistant bacterial infections. There are two general modes: Multi-Gene Lysis (MGL), used by dsDNA phages, and Single-Gene Lysis (SGL), used by small single-strand nucleic acid phages. At minimum, MGL systems require a muralytic enzyme, the endolysin, that degrades the cell wall or peptidoglycan (PG), and a small membrane protein, the holin, that actively programs the function of the endolysin. At least 10 more classes of phage lysis proteins have also been identified, including spanins functioning in destruction of the outer membrane in Gram-negative infections or acting as regulators of holin and endolysin function. The lysis pathways have steps that both respond to and cause biophysical changes in the host membrane, as well as featuring multiple examples of dynamic membrane topology and massive quaternary rearrangements, ultimately resulting in holes in the bacterial membrane of unprecedented micron-scale. Overall, these complex MGL systems make lysis a precisely-controlled, all-or- nothing phenomenon. In contrast, the small ssDNA and ssRNA phages have no genomic room for MGL systems. Instead a single Sgl (single gene lysis) protein acts to cause dysfunction in host PG biosynthesis or homeostasis, eventually leading to a host autolysis. One class of Sgl’s that block steps in cell wall biosynthesis has been established and designated as Protein Antibiotics, but the target of more than 20 other Sgl’s identified by bioinformatics and phage genetics is not known. In the next five years, the focus will not only be on the remarkable spanins, which fuse membranes during lysis, but also on two new classes of MGL proteins: releasins and disruptins. Releasins are unique in licensing dynamic membrane topology of endolysins. Disruptins are small, amphipathic proteins that are used to weaken the outer membrane; surprisingly, when purified and used in vitro, they function as phage-encoded versions of the cationic antimicrobial peptides (CAMPs) produced by mammalian cells. The unique power of phage genetics will be used to determine the mechanisms of both these new MGL proteins. Our biophysical and structural collaborators will be supp;oed with mutants, phenotypes and constructs to be used in characterizing lysis at both the atomic level and in the context of the infected single cell. In the SGL area, the recent hyper-expansion of the metagenomics of ssRNA phages will be exploited to solve the targets of many new Sgl proteins. The hypothesis is that ssRNA phage Sgl proteins have evolved to attack every step in host cell wall synthesis and homeostasis. Also, a new model that a major class of Sgl’s acts by binding the universal cell wall precursor, Lipid II, will be tested.

作为生物圈中最常见的胞质事件，通过噬菌体对宿主细胞的裂解是真正的 基本过程。此外，了解噬菌体裂解的分子基础现在在临床上相关 因为噬菌体疗法正在成为针对多药抗性细菌感染的重要工具。 有两种一般模式：多基因裂解（MGL），DSDNA噬菌体使用，单基因裂解（SGL）， 由小的单链核酸噬菌体使用。至少，MGL系统需要一种muralytic酶， 内olysin，会降解细胞壁或胡椒糖（PG），以及一个小的膜蛋白，霍林， 积极编程内溶素的功能。至少有10种噬菌体裂解蛋白也已经 鉴定出，包括在革兰氏阴性感染中破坏外膜或 充当霍林和内olysin功能的调节剂。裂解途径具有响应和 引起宿主膜的生物物理变化，并具有多个动态膜的例子 拓扑结构和大规模的第四纪重排，最终导致细菌膜的孔 前所未有的微观尺度。总体而言，这些复杂的MGL系统使裂解成为精确控制的，全或 没有什么现象。 相反，小ssDNA和ssRNA噬菌体没有用于MGL系统的基因组空间。而是一个 SGL（单基因裂解）蛋白起作用在宿主PG生物合成或稳态中引起功能障碍，最终 导致宿主自动分解。已经建立了细胞壁生物合成中的块步骤的一类SGL，并且 被指定为蛋白质抗生素，但是其他20多种SGL的靶标。 噬菌体遗传学尚不清楚。 在接下来的五年中，重点不仅将放在奇特的束缚上 裂解，但也对两种新的MGL蛋白质：释放和破坏蛋白。发行素在许可方面是独一无二的 内叶蛋白的动态膜拓扑。干扰蛋白是小的两亲蛋白，用于 削弱外膜；令人惊讶的是，当纯化并在体外使用时，它们用作噬菌体编码 由哺乳动物细胞产生的阳离子抗菌胡椒（CAMP）的版本。独特的力量 噬菌体遗传学将用于确定这两种新的MGL蛋白的机制。我们的生物物理 结构合作者将与突变体，表型和构造有关 表征原子水平和感染单细胞的背景下的裂解。在SGL区域， 将探索ssRNA噬菌体的宏基因组学的最新超扩张，以解决许多目标的目标 新的SGL蛋白。假设是ssRNA噬菌体SGL蛋白已经演变为攻击宿主细胞中的每个步骤 墙合成和稳态。此外，这是一个新模型，该模型通过绑定通用细胞来使SGL的行为构成主要类别 将测试壁前体脂质II。