A previously unrecognized class of fungal ice-nucleating proteins with bacterial ancestry
Ice-nucleating proteins (INpros) catalyze ice formation at high subzero temperatures, with major biological and environmental implications. While bacterial INpros have been structurally characterized, their counterparts in other organisms have remained largely unknown. Here, we identify membrane-independent proteins in fungi of the <i>Mortierellaceae</i> family that promote ice formation with high efficiency. These proteins are predicted to adopt β-solenoid folds and multimerize to form extended ice-binding surfaces, exhibiting mechanistic parallels with bacterial INpros. Structural modeling, phylogenetic analysis, and heterologous gene expression leading to ice nucleation in <i>Escherichia coli</i> and <i>Saccharomyces cerevisiae</i> show that the fungal INpros are encoded by orthologs of the bacterial <i>InaZ</i> gene, which was likely acquired by a fungal ancestor through horizontal gene transfer. The discovery of cell-free fungal INpros provides tools for innovative freezing applications and reveals biophysical constraints on ice nucleation across life.
Authors
- Ingrid de Almeida Ribeiro (ORCID: https://orcid.org/0000-0002-8418-3806)
- Mariah Rojas (ORCID: https://orcid.org/0000-0001-5535-7742)
- Kaden Shaw (ORCID: https://orcid.org/0000-0001-8810-3503)
- Mischa Bonn (ORCID: https://orcid.org/0000-0001-6851-8453)
- Kassaye Belay (ORCID: https://orcid.org/0000-0001-6402-7200)
- Konrad Meister (ORCID: https://orcid.org/0000-0002-6853-6325)
- H. Q. Liu
- J. Fröhlich-Nowoisky
- Boris Alexander Vinatzer (ORCID: https://orcid.org/0000-0003-4612-225X)
- Rajiv Berry (ORCID: https://orcid.org/0000-0001-6355-8667)
- Valeria Molinero (ORCID: https://orcid.org/0000-0002-8577-4675)
- Galit Renzer
- Parkesh Suseendran
- Xiaofeng Wang (ORCID: https://orcid.org/0000-0002-3850-3274)
- Rosemary J. Eufemio
- Hao-Bo Guo
- Ulrich Pöschl
Institutions
- Boise State University (US)
- University of Utah (US)
- Wright-Patterson Air Force Base (US)
- Max Planck Institute for Polymer Research (DE)
- Max Planck Institute for Chemistry (DE)
- Virginia Tech (US)
Publication Details
- Journal
- Science Advances
- Published
- 2026-03-11
- DOI
- https://doi.org/10.1126/sciadv.aed9652
- Primary Topic
- Physiological and biochemical adaptations
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- U.S. Department of Defense
- U.S. Department of Agriculture
- Boise State University
- Max-Planck-Gesellschaft
- National Institute of Food and Agriculture