CAREER: Elucidating Biogenic Control of Heterogenous Ice Nucleation

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.