Structure and Protein-Protein Interactions of Ice Nucleation Proteins Drive Their Activity.

Autor:	Hartmann S; Institute for Tropospheric Research, Leipzig, Germany., Ling M; Department of Biology, Microbiology Section, Aarhus University, Aarhus, Denmark.; Department of Physics and Astronomy, Stellar Astrophysics Centre, Aarhus University, Aarhus, Denmark.; Department of Molecular Biology and Genetics, Section for Protein Science, Aarhus University, Aarhus, Denmark., Dreyer LSA; Department of Molecular Biology and Genetics, Section for Protein Science, Aarhus University, Aarhus, Denmark., Zipori A; Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel., Finster K; Department of Biology, Microbiology Section, Aarhus University, Aarhus, Denmark.; Department of Physics and Astronomy, Stellar Astrophysics Centre, Aarhus University, Aarhus, Denmark., Grawe S; Institute for Tropospheric Research, Leipzig, Germany., Jensen LZ; Department of Biology, Microbiology Section, Aarhus University, Aarhus, Denmark.; Department of Physics and Astronomy, Stellar Astrophysics Centre, Aarhus University, Aarhus, Denmark.; Department of Molecular Biology and Genetics, Section for Protein Science, Aarhus University, Aarhus, Denmark., Borck S; Department of Biology, Microbiology Section, Aarhus University, Aarhus, Denmark.; Department of Physics and Astronomy, Stellar Astrophysics Centre, Aarhus University, Aarhus, Denmark.; Department of Molecular Biology and Genetics, Section for Protein Science, Aarhus University, Aarhus, Denmark., Reicher N; Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel., Drace T; Department of Molecular Biology and Genetics, Section for Protein Science, Aarhus University, Aarhus, Denmark., Niedermeier D; Institute for Tropospheric Research, Leipzig, Germany., Jones NC; Department of Physics and Astronomy, The Institute for Storage Ring Facilities, Aarhus University, Aarhus, Denmark., Hoffmann SV; Department of Physics and Astronomy, The Institute for Storage Ring Facilities, Aarhus University, Aarhus, Denmark., Wex H; Institute for Tropospheric Research, Leipzig, Germany., Rudich Y; Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel., Boesen T; Department of Molecular Biology and Genetics, Section for Protein Science, Aarhus University, Aarhus, Denmark.; Interdisciplinary Nanoscience Center and Center for Electromicrobiology, Aarhus University, Aarhus, Denmark., Šantl-Temkiv T; Department of Biology, Microbiology Section, Aarhus University, Aarhus, Denmark.; Department of Physics and Astronomy, Stellar Astrophysics Centre, Aarhus University, Aarhus, Denmark.
Jazyk:	angličtina
Zdroj:	Frontiers in microbiology [Front Microbiol] 2022 Jun 17; Vol. 13, pp. 872306. Date of Electronic Publication: 2022 Jun 17 (Print Publication: 2022).
DOI:	10.3389/fmicb.2022.872306
Abstrakt:	Microbially-produced ice nucleating proteins (INpro) are unique molecular structures with the highest known catalytic efficiency for ice formation. Airborne microorganisms utilize these proteins to enhance their survival by reducing their atmospheric residence times. INpro also have critical environmental effects including impacts on the atmospheric water cycle, through their role in cloud and precipitation formation, as well as frost damage on crops. INpro are ubiquitously present in the atmosphere where they are emitted from diverse terrestrial and marine environments. Even though bacterial genes encoding INpro have been discovered and sequenced decades ago, the details of how the INpro molecular structure and oligomerization foster their unique ice-nucleation activity remain elusive. Using machine-learning based software AlphaFold 2 and trRosetta, we obtained and analysed the first ab initio structural models of full length and truncated versions of bacterial INpro. The modeling revealed a novel beta-helix structure of the INpro central repeat domain responsible for ice nucleation activity. This domain consists of repeated stacks of two beta strands connected by two sharp turns. One beta-strand is decorated with a TxT amino acid sequence motif and the other strand has an SxL[T/I] motif. The core formed between the stacked beta helix-pairs is unusually polar and very distinct from previous INpro models. Using synchrotron radiation circular dichroism, we validated the β-strand content of the central repeat domain in the model. Combining the structural model with functional studies of purified recombinant INpro, electron microscopy and modeling, we further demonstrate that the formation of dimers and higher-order oligomers is key to INpro activity. Using computational docking of the new INpro model based on rigid-body algorithms we could reproduce a previously proposed homodimer structure of the INpro CRD with an interface along a highly conserved tyrosine ladder and show that the dimer model agrees with our functional data. The parallel dimer structure creates a surface where the TxT motif of one monomer aligns with the SxL[T/I] motif of the other monomer widening the surface that interacts with water molecules and therefore enhancing the ice nucleation activity. This work presents a major advance in understanding the molecular foundation for bacterial ice-nucleation activity. Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. (Copyright © 2022 Hartmann, Ling, Dreyer, Zipori, Finster, Grawe, Jensen, Borck, Reicher, Drace, Niedermeier, Jones, Hoffmann, Wex, Rudich, Boesen and Šantl-Temkiv.)
Databáze:	MEDLINE
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