Collaborative Research: Physical parameters controlling viral DNA packaging and ejection

合作研究：控制病毒 DNA 包装和排出的物理参数

• 批准号: 1715293
• 负责人: Paul Jardine
• 金额: $ 20万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1715293&HistoricalAwards=false
• 关键词: Collaborative; Research; Physical; parameters; controlling

Viruses are small infectious agents that only replicate inside the living cells of other organisms and can infect all types of life forms. This research will improve the understanding of key steps in the life-cycle of many viruses, the packaging of the DNA during viral assembly and the ejection of the DNA during infection of a host cell, as well as how these processes depend on the physical behavior of the tightly packed DNA. The project will not only shed light on the fundamental biology of viruses, but also on the physics of tightly confined DNA and the regulation of biological molecular motors which transport DNA. Graduate and undergraduate students will receive interdisciplinary training in the application of physics techniques to biology research and new experimental laboratory course materials will also be developed. K-12 outreach activities will be conducted and grade-school educational materials, including science books, kits, and games, will be evaluated for quality and scientific accuracy to provide online recommendations to schools and museums.Recent studies have shown that the kinetics of the packaging of double stranded DNA in bacterial viruses is dominated by the dynamics and energetics of the tightly packed DNA. In the biological regime to be studied, with repulsive DNA-self interactions, the DNA relaxes only very slowly towards an equilibrium conformation. Large forces build that resist DNA confinement and later help drive ejection during infection of a host cell. Bacteriophage phi29 will be studied as a model system and the packaging of single DNA molecules will be directly measured with optical tweezers. The dependence of packaging kinetics on initial motor velocity, dependent on ATP concentration, will be studied. Lower initial velocity is hypothesized to reduce formation of highly unfavorable DNA conformations, yielding decreased heterogeneity in the dynamics, lower relative slowing during filling, and less motor pausing, slipping, and stalling. A hypothesis to be tested is that allosteric regulation of the portal motor helps packaging complete as fast as possible by throttling down the motor velocity to mitigate formation of unfavorable DNA conformations. How packaging kinetics, force, and DNA relaxation depend on temperature and ionic conditions will also be studied. Motor velocity increases significantly with temperature, and motor slowing during filling depends on ionic screening conditions. Whereas faster initial velocity may cause greater relative slowing during filling, increased temperature or ionic screening may accelerate DNA relaxation. How packaging conditions and aging affect DNA ejection and viral infectivity will also be studied. Conditions affecting the DNA conformation during packaging, and aging, may impact DNA ejection. Conditions that increase forces resisting packaging or decrease DNA relaxation time may enhance ejection. The biological impact of these parameters will be investigated by examining their effects on virus infectivity.

病毒是仅在其他生物体的活细胞内复制并可以感染所有类型的生命形式的小型感染剂。这项研究将提高人们对许多病毒生命周期的关键步骤的理解，病毒组装过程中DNA的包装以及在宿主细胞感染期间DNA的射击以及这些过程如何取决于紧密堆积的DNA的身体行为。该项目不仅会阐明病毒的基本生物学，而且还阐明了紧密限制DNA的物理和传输DNA的生物分子电机的调节。 研究生和本科生将接受跨学科的培训，以应用物理技术在生物学研究中应用，并还将开发新的实验实验室课程材料。 K-12将进行K-12外展活动，并将评估包括科学书籍，套件和游戏在内的年级教育材料，以提供质量和科学的准确性，以向学校和博物馆提供在线建议。经过的研究表明，细菌病毒中双链DNA包装的动力学由细菌病毒中的双链DNA包装在动力学和精力充沛的密封性包装DNA的动力学和能量。在要研究的生物学状态下，具有排斥性的DNA自我相互作用，DNA仅在平衡构象方面放松得非常缓慢。大力构建可抵抗DNA限制的大力，后来有助于在宿主细胞感染期间驱动射血。噬菌体PHI29将作为模型系统进行研究，单个DNA分子的包装将直接用光学镊子进行测量。将研究包装动力学对初始运动速度（取决于ATP浓度）的依赖性。假设初始速度较低，以减少高度不利的DNA构象的形成，使动力学的异质性降低，填充过程中的相对减速降低，并减少运动暂停，滑动和失速。要测试的假设是，门户电机的变构调节通过降低运动速度以减轻不利的DNA构象的形成，从而尽快完成包装。还将研究包装动力学，力和DNA弛豫如何取决于温度和离子条件。运动速度随温度而显着增加，填充过程中的电动机放慢取决于离子筛选条件。虽然更快的初始速度可能会导致填充过程中的相对减速更大，但温度或离子筛选可能会加速DNA弛豫。 包装条件和衰老如何影响DNA射血和病毒感染性。影响包装和衰老过程中DNA构象的条件可能会影响DNA射精。增加抵抗包装或减少DNA松弛时间的力的条件可能会增强弹出率。这些参数的生物学影响将通过检查其对病毒感染性的影响来研究。

项目成果

Slow and steady wins the race: physical limits on the rate of viral DNA packaging

• DOI: 10.1016/j.coviro.2019.03.002
• 发表时间: 2019-06-01
• 期刊: CURRENT OPINION IN VIROLOGY
• 影响因子: 5.9
• 作者: Jardine, Paul J.