Mechanisms of Adaptation of Extracellular Nucleases to Extreme Conditions

在化学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体的酶。在长期被认为没有生命之后，人们已经清楚地认识到，地球深处的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地壳被认为包含了地球上90%的微生物生物量。在海洋中，病毒和噬菌体的数量是微生物的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，包括大量的脱氧核糖核酸（DNA）。这项研究的目标酶是DNA酶，它可以分解DNA聚合物。了解这些来自深海的酶和来自表面细菌的酶之间的差异，有望为了解序列和进化如何调节功能提供见解，并可能为生物技术应用产生新的酶。作为这些研究更广泛影响的一部分，从高中到本科和研究生水平的学生将通过在线和实验室体验接受结构基因组学和生物物理学的培训。大量海洋微生物表现出胞外dna酶（exNuc）活性，强调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。最近的研究进展将实验方法的进步与日益强大的计算工具相结合，揭示了动力学在调节生物化学活性中的核心作用，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，来自表层生物的生物分子在深层生物圈的极端条件下不起作用。目前的工作将结合实验和计算生物物理学方法，加上高压（核磁共振，荧光，x射线衍射，小角度x射线散射（SAXS）和分子模型）来解决这些外切酶序列如何在高压和高温和低温的极端条件下进化以保持功能的基本问题。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。

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.