title: Cryo-protective effect of an ice-binding protein derived from Antarctic bacteria.
abstract: Cold environments are populated by organisms able to contravene deleterious effects of low temperature by diverse adaptive strategies, including the production of ice binding proteins (IBPs) that inhibit the growth of ice crystals inside and outside cells. We describe the properties of such a protein (EfcIBP) identified in the metagenome of an Antarctic biological consortium composed of the ciliate Euplotes focardii and psychrophilic non-cultured bacteria. Recombinant EfcIBP can resist freezing without any conformational damage and is moderately heat stable, with a midpoint temperature of 66.4 °C. Tested for its effects on ice, EfcIBP shows an unusual combination of properties not reported in other bacterial IBPs. First, it is one of the best-performing IBPs described to date in the inhibition of ice recrystallization, with effective concentrations in the nanomolar range. Moreover, EfcIBP has thermal hysteresis activity (0.53 °C at 50 μm) and it can stop a crystal from growing when held at a constant temperature within the thermal hysteresis gap. EfcIBP protects purified proteins and bacterial cells from freezing damage when exposed to challenging temperatures. EfcIBP also possesses a potential N-terminal signal sequence for protein transport and a DUF3494 domain that is common to secreted IBPs. These features lead us to hypothesize that the protein is either anchored at the outer cell surface or concentrated around cells to provide survival advantage to the whole cell consortium.
authors.affiliation: Department of Biotechnology and Biosciences, State University of Milano-Bicocca, Italy.
authors.forename: Marco
authors.initials: M
authors.lastname: Mangiagalli
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Maya
authors.initials: M
authors.lastname: Bar-Dolev
authors.affiliation: Institute of Protein Biochemistry, National Research Council, Naples, Italy.
authors.forename: Pietro
authors.initials: P
authors.lastname: Tedesco
authors.affiliation: Department of Biotechnology and Biosciences, State University of Milano-Bicocca, Italy.
authors.forename: Antonino
authors.identifier: 0000-0002-1489-272X
authors.initials: A
authors.lastname: Natalello
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.|Department of Food Processing, Faculty of Chemical and Materials Technology, Tallinn University of Technology, Estonia.
authors.forename: Aleksei
authors.initials: A
authors.lastname: Kaleda
authors.affiliation: Department of Biotechnology and Biosciences, State University of Milano-Bicocca, Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Brocca
authors.affiliation: Institute of Protein Biochemistry, National Research Council, Naples, Italy.
authors.forename: Donatella
authors.initials: D
authors.lastname: de Pascale
authors.affiliation: School of Biosciences and Veterinary Medicine, University of Camerino, Italy.
authors.forename: Sandra
authors.initials: S
authors.lastname: Pucciarelli
authors.affiliation: School of Biosciences and Veterinary Medicine, University of Camerino, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Miceli
authors.affiliation: Institute of Biochemistry, Food Science and Nutrition, The Robert H. Smith Faculty of Agriculture, Food and Environment, The Hebrew University of Jerusalem, Rehovot, Israel.
authors.forename: Ido
authors.identifier: 0000-0001-8985-8211
authors.initials: I
authors.lastname: Braslavsky
authors.affiliation: Department of Biotechnology and Biosciences, State University of Milano-Bicocca, Italy.
authors.forename: Marina
authors.initials: M
authors.lastname: Lotti
mesh_terms: D000222:Adaptation, Physiological; D000595:Amino Acid Sequence; D000864:Antarctic Regions; D021301:Antifreeze Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D059001:Aquatic Organisms; D001419:Bacteria / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D003080:Cold Temperature; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D016812:Euplotes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D007053:Ice / Q000032:analysis*; D007700:Kinetics; D054892:Metagenome; D008958:Models, Molecular; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D021382:Protein Sorting Signals; D055550:Protein Stability; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D021301:Antifreeze Proteins; D007053:Ice; D021382:Protein Sorting Signals; D011994:Recombinant Proteins
keywords: Euplotes focardii consortium; cold adaptation; ice binding protein; ice recrystallization inhibition; thermal hysteresis