Collaborative Research: Unraveling the Structure and Mode of Action of Fungal Ice Nucleators

一些适应低温的真菌含有能够催化水冻结的特殊能力的化合物。众所周知，这些真菌在大气层中起到了造冰的作用；然而，人们对这些真菌化合物如何在冰核形成中发挥作用，或者它们在影响地球气候方面所起的作用知之甚少。该项目旨在揭开真菌优化冰层形成能力的工作机制，并提高我们对这些真菌如何影响降雨量和强度以及影响地球气候的理解。由于这些真菌也是植物病原体，这项研究还将有助于了解真菌冰核对作物和根际的影响，并为设计和准备强大的新冷冻技术提供新的策略。该项目的跨学科性质将为本科生和研究生提供新的学习机会。阿拉斯加东南大学是一所农村本地人为主的本科院校，来自阿拉斯加东南大学的人数较少的学生将有独特的机会学习先进的生物分析技术、晶体生长和先进的光谱学，并将通过对等指导和与贝勒大学研究生的互动鼓励他们进入研究生院学习。贝勒大学的研究生将通过与阿拉斯加原住民本科生的合作，获得独特的研究阿拉斯加生物结合冰的生物分子的研究经验，并获得独特的指导经验。由于与产生初始结晶核相关的能量障碍，纯水在0°C不会结冰。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。来自真菌的冰核生物分子(INBS)是已知的最好的冰核物质之一，能够在接近0°C的温度下形成冰。真菌INBS对水的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个学科直接相关。尽管它们很重要，但INB介导的冷冻背后的结构基础和分子机制在很大程度上仍然难以捉摸。要回答是什么使INBS在成冰方面比任何其他材料都要好这一问题取得进展，需要对其自然环境中能够实现更好的成冰的结构和相互作用的微观图景进行描述。该项目的主要目标是：1)鉴定和表征真菌中导致冰核形成的化合物和结构基团；2)确定化合物在制冰过程中的构象变化；3)确定化合物在制冰过程中水合壳的变化。这些目标将使用新的冰结合分析和先进的光谱方法来实现。这项研究将允许推导出INBS的一般结构-功能关系和最佳功能，使人们能够前所未有地深入了解生物冰核的分子基础。该项目由分子和细胞生物科学部(MCB)和既定的刺激竞争研究计划(EPSCoR)联合资助。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。

Some cold-adapted fungi contain compounds with the unusual capability to catalyze the freezing of water. These fungi are known to have a role in making ice in the atmosphere; however, little is known about how these fungal compounds function in ice nucleation or the role they have in influencing the earth’s climate. This project seeks to unravel the working mechanism of fungi’s ability to optimize ice formation and to improve our understanding of how these fungi influence the amount and intensity of precipitation and impact the earth’s climate. Because these fungi are also plant pathogens, this research will also help with understanding the impact of fungal ice nucleation on crops and the rhizosphere and enable new strategies for the design and preparation of powerful new freezing technologies. The interdisciplinary nature of the project will provide novel learning opportunities for undergraduate and graduate students. Underrepresented students from the University of Alaska Southeast, a rural native-serving Primarily Undergraduate Institution, will have unique opportunities to learn advanced bioanalytical techniques, crystal growth, and advanced spectroscopy and will be encouraged to attend graduate school through peer-to-peer mentoring and interactions with graduate students from Baylor University. Graduate students from Baylor University will have unique research experiences studying ice-binding biomolecules of organisms inhabiting Alaska and a unique mentoring experience through working with rural, Alaska Native undergraduates.Pure water does not freeze at 0 °C owing to the energy barrier associated with creating the initial crystallization nucleus. In nature, water typically freezes in a heterogeneous process, facilitated by the presence of particles that serve as ice nucleators. Ice-nucleating biomolecules (INBs) from fungi are among the best ice nucleators known, enabling the formation of ice at temperatures close to 0 °C. The control fungal INBs 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 structural basis and molecular mechanisms behind INB-mediated freezing have remained largely elusive. Progress towards answering the question of what makes INBs so much better at nucleating ice than any other material requires a microscopic picture of the structure and interactions that enable superior ice nucleation in their natural environment. The main objectives of this project are: 1) Identify and characterize the compounds and structural moieties responsible for ice nucleation in fungi, 2) Determine conformational changes of the compounds when they make ice, and 3) Determine changes in the hydration shell of the compounds in the process of ice making. These objectives will be accomplished using novel ice-binding assays and advanced spectroscopic methods. This research will allow the derivation of general structure-function relationships and optimal functionalities of INBs, enabling unprecedented insights into the molecular basis of biological ice nucleation.This project is jointly funded by Molecular and Cellular Biosciences (MCB) Division 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.