nonprotein thermal hysteresis-producing xylomannan antifreeze in the freeze-tolerant Alaskan beetle Upis ceramboides

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 106; no. 48; pp. 20210 - 20215
• Main Authors: Walters, Kent R. Jr, Serianni, Anthony S, Sformo, Todd, Barnes, Brian M, Duman, John G
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01-12-2009; National Acad Sciences
• Series: From the Cover
• Subjects: Adaptation, Biological - physiology; Alaska; Amino acids; Animals; Antifreeze proteins; Antifreeze Proteins - chemistry; Antifreeze solutions; Antifreezes; Biochemistry; Biological Sciences; carbohydrate structure; Cell membranes; Chemical equilibrium; cold tolerance; Coleoptera - chemistry; Electrophoresis, Polyacrylamide Gel; Freezing; Gels; hysteresis; Ice; Insects; Lipids; Magnetic Resonance Spectroscopy; mannans; Molecular biology; Molecular Structure; Molecules; Proteins; Spectral resolution; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Spectrophotometry, Ultraviolet; Spectrum analysis; Tenebrionidae; thermal hysteresis; thermal hysteresis factors; xylomannan
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0909872106

Thermal hysteresis (TH), a difference between the melting and freezing points of a solution that is indicative of the presence of large-molecular-mass antifreezes (e.g., antifreeze proteins), has been described in animals, plants, bacteria, and fungi. Although all previously described TH-producing biomolecules are proteins, most thermal hysteresis factors (THFs) have not yet been structurally characterized, and none have been characterized from a freeze-tolerant animal. We isolated a highly active THF from the freeze-tolerant beetle, Upis ceramboides, by means of ice affinity. Amino acid chromatographic analysis, polyacrylamide gel electrophoresis, UV-Vis spectrophotometry, and NMR spectroscopy indicated that the THF contained little or no protein, yet it produced 3.7 ± 0.3 °C of TH at 5 mg/ml, comparable to that of the most active insect antifreeze proteins. Compositional and structural analyses indicated that this antifreeze contains a β-mannopyranosyl-(1[rightward arrow]4) β-xylopyranose backbone and a fatty acid component, although the lipid may not be covalently linked to the saccharide. Consistent with the proposed structure, treatment with endo-β-(1[rightward arrow]4)xylanase ablated TH activity. This xylomannan is the first TH-producing antifreeze isolated from a freeze-tolerant animal and the first in a new class of highly active THFs that contain little or no protein.