Scope of collateral fitness effects and their mechanisms

了解蛋白质突变的影响对分子进化的研究至关重要。有害突变通常被理解为通过破坏受影响蛋白质的正常功能而产生负面影响。然而，突变的有害影响也可能来自于导致突变蛋白做它不应该做的事情，比如干扰不相关的生物过程。这个项目是对三种蛋白质中所有可能突变的影响的系统研究。这将有助于理解蛋白质是如何进化的，以及突变影响细胞生理的机制。这些知识对于了解人类疾病和抗生素耐药性的演变非常重要。在这项研究中，每年将有三名研究生、两名本科生和一名高中生接受研究培训。研究生将在科学会议上展示研究成果，并获得指导本科生和高中生的指导经验。突变适应度效应的分布在设定蛋白质进化速率中起着核心作用，但这种约束的分子基础尚不清楚。一种可能性是突变蛋白错误折叠或与其他蛋白发生错误相互作用，造成有害后果。这些效应是附带适应性效应的例子，与源于蛋白质生理功能变化的主要适应性效应相反。我们对附带适应度效应的频率、幅度和机制知之甚少，但这些信息对于理解蛋白质进化至关重要。本研究将利用生长竞争和下一代测序技术在大肠杆菌中全面确定三种蛋白质突变的附带适应度效应。分子生物学技术将用于发现选择突变效应背后的机制。这项研究将产生丰富的数据，从中了解附带适应度效应对进化的贡献。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding the effects of protein mutations is fundamentally important in the study of molecular evolution. Harmful mutations are generally understood to cause negative effects by disrupting the normal functions of the affected protein. However, the deleterious effects of mutations might also arise from causing the mutated protein to do things it should not do, such as interfere with unrelated biological processes. This project is a systematic study of the effects of all possible mutations in three proteins. This will contribute to the understanding of how proteins evolve and the mechanisms by which mutations can affect cell physiology. Such knowledge is important for understanding human disease and the evolution of antibiotic resistance. Each year of this research, three graduate students, two undergraduates, and one high school student will be trained in research. The graduate students will present research at scientific conferences and gain mentorship experience supervising the undergraduate and high school students. The distribution of fitness effects of mutations plays a central role in setting protein evolution rates, but the molecular underpinnings of this constraint are unclear. One possibility is that mutant proteins misfold or misinteract with other proteins with deleterious consequences. Such effects are examples of collateral fitness effects, as opposed to primary fitness effects that derive from changes in the physiological function of the protein. Very little is known about the frequency, magnitude, and mechanisms of collateral fitness effects, but such information is critical for understanding protein evolution. This research will comprehensively determine the collateral fitness effects of mutations in three proteins using growth competition and next-generation sequencing techniques in Escherichia coli. Molecular biology techniques will be used to discover the mechanisms behind select mutational effects. This study will generate a wealth of data from which to understand the contribution of collateral fitness effects to evolution.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.