| Autor: |
Schwidetzky R; Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz 55128, Germany., de Almeida Ribeiro I; Department of Chemistry, The University of Utah, Salt Lake City, UT 84112., Bothen N; Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany., Backes AT; Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany., DeVries AL; Department of Animal Biology, University of Illinois at Urbana-Champaign, Urbana, IL 61801., Bonn M; Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz 55128, Germany., Fröhlich-Nowoisky J; Multiphase Chemistry Department, Max Planck Institute for Chemistry, Mainz 55128, Germany., Molinero V; Department of Chemistry, The University of Utah, Salt Lake City, UT 84112., Meister K; Department of Molecular Spectroscopy, Max Planck Institute for Polymer Research, Mainz 55128, Germany.; Department of Chemistry and Biochemistry, Boise State University, Boise, ID 83725. |
| Abstrakt: |
Biological ice nucleation plays a key role in the survival of cold-adapted organisms. Several species of bacteria, fungi, and insects produce ice nucleators (INs) that enable ice formation at temperatures above -10 °C. Bacteria and fungi produce particularly potent INs that can promote water crystallization above -5 °C. Bacterial INs consist of extended protein units that aggregate to achieve superior functionality. Despite decades of research, the nature and identity of fungal INs remain elusive. Here, we combine ice nucleation measurements, physicochemical characterization, numerical modeling, and nucleation theory to shed light on the size and nature of the INs from the fungus Fusarium acuminatum . We find ice-binding and ice-shaping activity of Fusarium IN, suggesting a potential connection between ice growth promotion and inhibition. We demonstrate that fungal INs are composed of small 5.3 kDa protein subunits that assemble into ice-nucleating complexes that can contain more than 100 subunits. Fusarium INs retain high ice-nucleation activity even when only the ~12 kDa fraction of size-excluded proteins are initially present, suggesting robust pathways for their functional aggregation in cell-free aqueous environments. We conclude that the use of small proteins to build large assemblies is a common strategy among organisms to create potent biological INs. |
