ABSTRACT

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.

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