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P. Bieber, T.M. Seifried, F. Reyzek, N. Borduas-Dedekind, H. Grothe:
"The atmospheric ice nucleation behavior of biological macromolecules: how top-down and bottom-up approaches help disentangle the role of proteins";
Vortrag: EGU General Assembly 2022, Wien; 23.05.2022 - 27.05.2022; in: "EGU General Assembly 2022", Copernicus Publisher, (2022), S. #.

Certain biological macromolecules can play a unique role in heterogeneous ice nucleation, triggering freezing of atmospheric cloud droplets at high sub-zero temperatures (Pummer et al., 2012). Some ice nucleating proteins (INPs) of procaryotic organisms (e.g. Pseudomonas syringae) have been identified as highly efficient ice nuclei, but the isolation and identification of INPs from eucaryotic cells (e.g. pollen or fungal spores) remains challenging due to the increasing complexity of the samples´ matrices (Burkart et al., 2021, Seifried et al., 2020). To analyze INPs from birch pollen extracts, we applied a top-down workflow, including ice-shell purification, size exclusion chromatography and gel electrophoresis as separation techniques followed by fluorescence spectroscopy, infrared spectroscopy and mass spectrometry for characterization and the Vienna Optical Droplet Crystallization Analyzer (VODCA) for determining the ice nucleation activity (Felgitsch et al., 2018). We found several proteins as possible contributors to the freezing activity of birch pollen at around -16°C. However, the exact sequence of the INP and the molecular mechanism behind the ice nucleation remains elusive. To address this knowledge gap, we are currently focusing on a broader bottom-up approach which illuminates the ice nucleation mechanism of proteins in general. Specific peptides can be synthesized in-vitro and the ice nucleation activity of pure synthetic substances will be analyzed by using the drop Freezing Ice Nuclei Counter (FINC) (Miller et al., 2021). Exchanging or modifying single amino acids will allow to determine the mechanisms behind the nucleation and to draw a picture of sequences that indicate possible INPs in various organisms. Such a method can provide a basis for the investigations of INPs across the borders of genera and species and can help building fundamental understanding behind biologically induced ice nucleation at high sub-zero temperatures in the atmosphere.

http://dx.doi.org/10.5194/egusphere-egu22-13322

bioareosols, ice nucleation, heterogeneous ice nucleation, ice nuclei, INM