Control of Virus Induced Lysis

描述（由申请人提供）：本提案的重点是噬菌体裂解宿主的机制。基于最近的进展，建议研究holins的生化和遗传特性，holins是噬菌体编码的小膜蛋白，作为噬菌体感染的计时器。Holins具有在噬菌体感染周期中积累而不伤害细胞的非凡能力，然后突然触发渗透膜。这就终止了感染，并激活了一种叫做内溶酶或溶菌酶的水解酶，导致细胞壁的降解，导致细胞破裂，释放出后代病毒粒子。这项工作的目的是确定这些蛋白质如何在膜上形成孔，以及孔形成事件的调度如何被编程到空心蛋白的序列中。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，包括研究一些裂解蛋白的整体膜结构域实际上如何能够根据生理线索离开膜。

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.