CAREER: Elucidating Biogenic Control of Heterogenous Ice Nucleation

水和冰在塑造地球地质、大气和维持生命方面是必不可少的。在所有这些情况下，生物冰核控制着水从液体冰晶到固体冰晶的转变。生物冰核可以导致植物遭受霜冻破坏，但也可以通过降雨促进植被生长。它们影响地表水、水文循环和气候。了解生物冰核是如何控制冰层形成的，对于气候模型、天气预报以及景观设计和农业决策至关重要。尽管这很重要，但生物冷冻背后的分子机制在很大程度上仍然难以捉摸。这个项目试图破译蛋白质作为制冰剂和减冰剂的优越性，超越所有其他物质。这一知识将使我们能够在理解我们所居住的生态系统的关键部分方面取得突破，为低温保存、环境友好的除冰和更新的气候模型提供迫切需要的投入。随着美国越来越多地在北极开展活动，新的冷冻技术也特别重要，那里的冰可能是后勤负担，也可能是行动的推动力。目前与冰有关的挑战不成比例地影响到农村、农业和以生计为基础的社区。该项目旨在通过服务学习和使用现代媒体提高农村学生对STEM的认识和兴趣，并帮助社区发展环境友好型能力，以便在不断变化的世界中更好地预测、导航和缓解与冰有关的挑战。纯水在0℃时不会冻结，这是因为与形成初始结晶核有关的能量障碍。在自然界中，水通常以一种不均匀的过程冻结，这是由于充当冰核的粒子的存在促进了水的冻结。细菌冰核蛋白(INP)是最著名的冰核物质，能够在接近0°C的温度下形成冰。生物INP对水的相变进行控制，与低温生物学、植物病理学、生物医学工程和气候科学等多个学科直接相关。尽管它们很重要，但INP介导的冷冻背后的结构和工作机制仍不清楚。要回答是什么使INP在成冰方面比任何其他材料都更好的问题取得进展，需要了解在其自然环境中使更好的冰成核得以实现的结构和相互作用的分子图像。本项目的主要研究目标是：1)阐明优势细菌成核冰的机制，2)揭示成冰能力与冰结合单元组装成大功能区之间的关系，3)通过加入冰结合蛋白作为构建块来开发一种仿生成冰方法。这项研究将允许推导出生物成冰剂的结构-功能关系和最佳功能，并将使可调材料的开发能够根据组装状态作为防冻剂或成冰剂。综合教育计划将利用针对农村社区的创新媒体推广和服务学习计划，激发对STEM机会的变革性认识，并使人们有机会共同发现有效的、对环境无害的冰控解决方案。该项目由分子和细胞生物科学部和既定的刺激竞争研究计划(EPSCoR)共同资助。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。

Water and ice are essential in shaping Earth's geology, atmosphere, and sustaining life. Biological ice nucleators control the transition of water from liquid to solid ice crystals in all these contexts. Biological ice nucleators can induce frost damage in plants, but can also promote vegetation growth by enabling rainfall. They impact surface water, the hydrological cycle, and climate. Understanding the how biological ice nucleators control ice formation is critical for climate models, weather prediction, and decision-making in landscape design and agriculture. Despite this importance, the molecular mechanisms behind biologically enabled freezing remain largely elusive. This project seeks to decipher the superiority of proteins as ice makers and mitigators, surpassing all other substances. This knowledge would enable breakthroughs in understanding key parts of the ecosystem we inhabit, with urgently needed input for cryopreservation, environmentally benign de-icing, and updated climate models. New freezing technologies are also particularly important as the U.S. increasingly pursues activities in the Arctic, where ice can be a logistical burden or an operational enabler. Current ice-related challenges disproportionally affect rural agricultural and subsistence-based communities. This project aims to enhance rural student engagement in STEM by fostering greater awareness and interest through service-learning and the use of modern media and to help the communities develop environmentally friendly capacities to better predict, navigate and mitigate ice-associated challenges in a changing world. Pure water does not freeze at 0 °C owing to the energy barrier associated with forming the initial crystallization nucleus. In nature, water usually freezes in a heterogeneous process, facilitated by the presence of particles that serve as ice nucleators. Bacterial ice-nucleating proteins (INP) are the best-known ice nucleators, enabling ice formation at temperatures close to 0 °C. The control biological INPs exert over the phase transition of water has direct relevance for disciplines as diverse as cryobiology, plant pathology, biomedical engineering, and climate science. Despite their importance, the structures and working mechanisms behind INP-mediated freezing remain unknown. Progress toward answering the question of what makes INPs so much better at nucleating ice than any other material requires a molecular picture of the structures and interactions that enable superior ice nucleation in their natural environment. The main research objectives of this project are: 1) Elucidate how superior bacterial ice nucleators nucleate ice, 2) Unravel the correlation between ice-nucleating abilities and assembly of ice-binding units into large functional domains 3) Develop a biomimetic approach to ice nucleation by incorporating ice-binding proteins as building blocks. This research will allow the derivation of structure-function relationships and optimal functionalities of biogenic ice nucleators, and will enable the development of tunable materials that can act as antifreeze or ice nucleating agents depending on the assembly state. Integrated educational initiatives will utilize innovative media outreach and service-learning programs targeted at rural communities to ignite a transformative awareness of STEM opportunities, and to enable opportunities to collectively discover effective and environmentally benign solutions for ice control.This project is jointly funded by the Division of Molecular and Cellular Biosciences and the Established Program to Stimulate Competitive Research (EPSCoR).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.