Biological ice formation - Probing the interplay between ice-nucleating protein structures and interfacial water with ultrafast 2D sum frequency generation (SFG) spectroscopy

Project Information

ProIce

Grant agreement ID: 101024120

DOI

10.3030/101024120

Project closed

EC signature date 26 February 2021

Start date 1 September 2021

End date 31 August 2023

Funded under

• EXCELLENT SCIENCE - Marie Skłodowska-Curie Actions

Total cost

€ 207 312,00

EU contribution

€ 207 312,00

Coordinated by

AARHUS UNIVERSITET
Denmark

Periodic Reporting for period 1 - ProIce (Biological ice formation - Probing the interplay between ice-nucleating protein structures and interfacial water with ultrafast 2D sum frequency generation (SFG) spectroscopy)

Reporting period: 2021-09-01 to 2023-08-31

Summary of the context and overall objectives of the project

Pure water freezes at temperatures as low as −40°C but in the presence of other materials and substances the freezing temperature is elevated. Ice-active bacteria are microorganisms that can freeze water at temperatures as high as −2°C and are thus the most efficient ice nucleators known so far. They are highly abundant across the globe, including in the atmosphere. They cause frost damage to wild and agricultural plants, and they influence rain and snow formation.
Ice-active bacteria grow ice crystals with the help of specialized ice-nucleating proteins (INPs), which are located at the outer membrane of the bacterium. Despite the essential role of INP-catalyzed water freezing for the entire ecosystem, the molecular mechanisms of this process have remained unclear. The objective of ProIce is to gain insights into the molecular interactions between INPs and water to better understand biological ice formation.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

The interactions between water and ice-nucleating proteins (INPs) were studied by means of advanced laser spectroscopic techniques. Sum frequency generation (SFG) spectroscopy was used to investigate three different INP model systems, and theoretical models were used to understand the experimental data. The conclusion of this work is that the activity of INPs is strongly affected by the pH in their local environment, which in turn controls the protein charge and its interactions with neighboring protein molecules. Effective protein-protein electrostatic interactions drive the formation of ordered protein layers at the air-water interface, which can increase the degree of order of the surrounding water network.
ProIce resulted in two articles that were published in high impact physical chemistry journals. One article is currently under review, and an additional one is being prepared. The results were presented at five international scientific conferences in the USA and Europe.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

ProIce addressed questions about the structure and dynamics of proteins and their interactions with water using spectroscopic techniques. A novel approach was implemented in the host laboratory, a two-color time-domain two-dimensional infrared spectrometer, that can be used in the future for other biological questions. The results regarding INP function are interesting for atmospheric and environmental researchers who study ice formation in clouds and in the polar regions.

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