CAREER: Elucidating Biogenic Control of Heterogenous Ice Nucleation

水和冰对于塑造地球的地质、大气和维持生命至关重要。在所有这些情况下，生物冰核控制着水从液体到固体冰晶的转变。生物冰核可以引起植物的霜冻损害，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。了解生物冰核如何控制冰的形成对气候模型、天气预报、景观设计和农业决策至关重要。尽管如此重要，生物冷冻背后的分子机制仍然难以捉摸。该项目旨在破译蛋白质作为制冰和减缓剂的优越性，超越所有其他物质。这些知识将使我们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、无害环境的除冰和更新气候模型提供迫切需要的输入。随着美国越来越多地在北极开展活动，新的冷冻技术也变得尤为重要。在北极，冰可能成为后勤负担，也可能成为行动的推手。当前与冰有关的挑战对农村农业和以生存为基础的社区的影响尤为严重。该项目旨在通过服务学习和现代媒体的使用，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、应对和缓解与冰相关的挑战。由于与形成初始结晶核有关的能垒，纯水在0°C时不会冻结。在自然界中，水通常在非均相过程中结冰，这是由于充当冰核的粒子的存在而促成的。细菌冰核蛋白（INP）是最著名的冰核蛋白，能够在接近0°C的温度下形成冰。生物INPs对水相变的控制与低温生物学、植物病理学、生物医学工程和气候科学等多种学科直接相关。尽管它们很重要，但inp介导的冻结背后的结构和工作机制仍然未知。为什么INPs比其他任何材料都更容易成核，要想回答这个问题，就需要一个分子结构和相互作用的图像，这些结构和相互作用使它们在自然环境中具有优越的成核能力。本项目的主要研究目标是：1)阐明优秀的细菌冰核细胞如何成核冰；2)揭示冰核能力与冰结合单元组装成大功能域之间的关系；3)通过将冰结合蛋白作为构建块，开发一种模拟冰核的方法。这项研究将允许推导出生物冰成核剂的结构-功能关系和最佳功能，并将使可调材料的开发成为可能，这些材料可以根据组装状态作为防冻剂或冰成核剂。综合教育计划将利用创新的媒体宣传和针对农村社区的服务学习计划，激发人们对STEM机会的变革意识，并使人们有机会共同发现有效和环保的治冰解决方案。该项目由分子和细胞生物科学部和刺激竞争性研究的既定计划（EPSCoR）共同资助。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。

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.