Mechanisms of Adaptation of Extracellular Nucleases to Extreme Conditions

在化学部生命过程化学项目的支持下，伦斯勒理工学院的凯瑟琳·罗耶教授将研究生活在深海环境中的生物的酶。在长期被认为没有生命之后，很明显，地球深层生物圈是巨大多样性生命的家园。事实上，深海以及大陆和海洋结壳被认为包含了地球上约90%的微生物生物量。海洋中存在的病毒和噬菌体的丰度是微生物的15倍。它们每天导致约20%的海洋微生物死亡，每年释放高达1450亿吨的碳，其中包括大量的脱氧核糖核酸(DNA)。这项工作的目标酶是DNA酶，它能分解DNA聚合体。了解深海和表层细菌的这些酶之间的差异，预计将有助于深入了解序列和进化是如何调整功能的，并可能产生新的生物技术应用酶。作为这些研究更广泛影响的一部分，将通过在线和实验室经验对从高中到本科生和研究生的学生进行结构基因组学和生物物理学方面的培训。大量的海洋微生物表现出胞外DNase(ExNuc)活性，这突显了这些酶在海洋生物膜动力学和地球生物化学循环中的重要性。最近的进展结合了实验方法的进步和日益强大的计算工具，揭示了动力学在调节生化活性方面的核心作用，以及氨基酸序列和反应条件对这些状态的调节。深海环境中唯一常见的物理参数是高压。人们早就知道，表层生物的生物分子在深层生物圈的极端条件下是不起作用的。目前的工作将结合实验和计算生物物理方法以及高压(核磁共振、荧光、X射线衍射、小角X射线散射(SAXS)和分子建模)来解决这些核酸外切酶序列如何进化以在高压和高、低温的极端条件下保持功能的基本问题。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

With the support of the Chemistry of Life Processes Program in the Chemistry Division, Professor Catherine Royer of Rensselaer Polytechnic Institute will investigate enzymes from organisms living in deep sea environments. After long being considered devoid of life, it has become clear that the Earth’s deep biosphere is home to an enormous diversity of life. In fact, the deep oceans and the continental and oceanic crusts are thought to contain ~90% of the Earth’s microbial biomass. Viruses and bacteriophages are present in the oceans at ~15-fold higher abundance than microbes. They contribute to the death of ~20% of all oceanic microbes every day, releasing up to 145 gigatons of carbon annually, including massive amounts of deoxyribonucleic acid (DNA). The enzymes being targeted in this work, Dnases, break up DNA polymers. Understanding the differences between these enzymes from the deep sea and those from surface bacteria is expected to provide insight into how sequence and evolution tune function and may yield new enzymes for biotechnological applications. As part of the broader impacts of these studies, students from high school to undergraduate and graduate levels will be trained in structural genomics and biophysics via online and laboratory experiences. Large numbers of marine microbes exhibit extracellular Dnase (exNuc) activity, underscoring the importance of these enzymes in oceanic biofilm dynamics and geobiochemical cycling. Recent progress combining advances in experimental approaches with increasingly powerful computational tools has revealed the central role of dynamics in regulating biochemical activity, and the modulation of these states by amino acid sequence and reaction conditions. The single common physical parameter in deep ocean environments is high pressure. It has long been known that biomolecules from surface organisms are not functional under the extreme conditions of the deep biosphere. The present work will combine experimental and computational biophysics approaches coupled with high pressure (NMR, fluorescence, X-ray diffraction, small angle X-ray scattering (SAXS) and molecular modeling) to address the fundamental question of how these exonuclease sequences have evolved to maintain function under extreme conditions of high pressure and of high and low temperature.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.