Control of Virus Induced Lysis

这项建议的重点是噬菌体对宿主的裂解机制。在最近的基础上 随着研究的进展，建议研究小噬菌体编码的Holins的生化和遗传特性 作为噬菌体感染计时器的膜蛋白。霍林斯有非凡的能力 在噬菌体感染周期中积累而不损害细胞，然后突然触发 使膜通透性。这终止了感染，并激活了称为 内溶素，或溶菌酶，导致细胞壁的降解，导致细胞破裂和释放 子代病毒粒子。这项工作的目的是确定这些蛋白质如何在膜上形成孔洞， 以及如何将成孔事件的调度编程到霍林序列中。 将讨论膜中脂质-蛋白质和蛋白质-蛋白质相互作用的基本问题， 包括对一些裂解蛋白的完整膜残基实际上如何能够退出的研究 在生理提示下的膜。 除了基因组非常小的噬菌体外，霍林-内溶素模式对所有噬菌体都是完全通用的。 然而，单链的DMA和RNA噬菌体，整个基因组只有3-10个基因 通过表达单个基因来补充、完成宿主裂解。在其中两个案例中，最近的进展 表明噬菌体裂解蛋白通过抑制粘蛋白前体中的不同酶而引起裂解。 生物合成途径。有人建议研究这些“蛋白质抗生素”的分子基础。 对这些保守的酶产生抑制作用。其他小的单链RNA噬菌体可通过 未知的机制，阐明这是这个项目的另一个目标。 公共卫生影响：这些研究对于我们理解细菌病毒或 噬菌体，杀死它们的猎物，并影响它们的后代的扩散。这可能会有直接的实际好处，因为 越来越多的人一致认为，噬菌体作为天然抗菌剂将成为人类免疫系统的重要工具。 抗击细菌病原体，这些病原体对现有抗生素的抗药性越来越强。此外， 研究可能会揭示化学抗生素设计的新模式。

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, smallphage-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 activatesmuralytic enzymes called endolysins, or lysozymes, resulting in degradationof 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 inmembranes, 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 membranedomains 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 RNAphages, limited to 3 - 10genes 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.