Control of Virus Induced Lysis

描述（由申请方提供）：本提案的重点是噬菌体裂解宿主的机制。基于最近的进展，建议调查holins，小噬菌体编码的膜蛋白，作为噬菌体感染的计时器的生化和遗传特性。洞蛋白具有在噬菌体感染周期期间积累而不伤害细胞的显著能力，然后突然触发以透化膜。这终止了感染并激活称为内溶素或溶菌酶的壁溶酶，导致细胞壁降解，导致细胞破裂并释放子代病毒体。这项工作的目的是确定这些蛋白质如何在膜上形成孔，以及孔形成事件的时间表如何被编程到孔蛋白的序列中。膜中的脂质-蛋白质和蛋白质-蛋白质相互作用的基本问题将得到解决，包括一些裂解蛋白质的膜结构域实际上是如何能够退出膜生理线索的调查。 孔蛋白-内溶素模式对于除了具有非常小的基因组的那些之外的所有微生物是完全通用的。然而，单链DNA和RNA内切酶，其整个基因组互补物限于3 - 10个基因，通过表达单个基因来完成宿主裂解。在其中两种情况下，最近的进展表明，噬菌体裂解蛋白通过抑制胞壁蛋白前体生物合成途径中的不同酶而引起裂解。建议研究这些“蛋白质抗生素”对这些保守酶的抑制作用的分子基础。其他小的单链RNA通过未知的机制影响裂解，阐明这是本项目的另一个目标。 对公共卫生的影响：这些研究对于我们理解细菌病毒或细菌如何杀死它们的猎物并影响其后代的传播至关重要。这可能具有直接的实际益处，因为越来越多的共识是，作为天然抗菌剂，抗生素将成为对抗细菌病原体的重要工具，这些病原体对可用的抗生素的耐药性越来越强。此外，该研究还可能为化学抗生素的设计提供新的模式。

DESCRIPTION (provided by applicant): The focus of this proposal is on the mechanism of host lysis by bacteriophage. Building on recent progress, it is proposed to investigate the biochemical and genetic properties of holins, small phage-encoded membrane proteins that act as the timers of phage infections. Holins have the remarkable ability to accumulate during the phage infective cycle without harming the cell, then suddenly triggering to permeabilize the membrane. This terminates the infection and activates muralytic enzymes called endolysins, or lysozymes, resulting in degradation of the cell wall, leading to bursting of the cell and release of the progeny virions. The work is aimed at determining how these proteins can form holes in membranes, and how the scheduling of the hole-forming event is programmed into the sequence of the holin. Fundamental issues of lipid-protein and protein-protein interactions in membranes will be addressed, including an investigation of how integral membrane domains of some lysis proteins actually are able to exit the membrane upon physiological cues. The holin-endolysin mode is completely general for all phages except those with very small genomes. However, single-stranded DMA and RNA phages, limited to 3 - 10 genes for their entire genome complement, accomplish host lysis by expressing single genes. In two of these cases, recent progress has shown that the phage lysis protein causes lysis by inhibiting different enzymes in the murein precursor biosynthetic pathway. It is proposed to investigate the molecular basis by which these "protein antibiotics" effect inhibition of these conserved enzymes. Other small single-stranded RNA phages effect lysis by an unknown mechanism, the elucidation of which is another goal of this project. Public health implications: These studies are critical to our understanding of how bacterial viruses, or phages, kill their prey and effect dispersal of their progeny. This may have direct practical benefits because there is a growing consensus that phages, as natural antibacterial agents, will become an important tool in combating bacterial pathogens, which are increasingly resistant to available antibiotics. In addition, the research may reveal new modes for design of chemical antibiotics.