Free-radical first responders: the characterization of CuZnSOD and MnSOD regulation during freezing of the freeze-tolerant North American wood frog, Rana sylvatica

Dawson, N. J. , Katzenback, B. A. and Storey, K. B. (2015) Free-radical first responders: the characterization of CuZnSOD and MnSOD regulation during freezing of the freeze-tolerant North American wood frog, Rana sylvatica. Biochimica et Biophysica Acta, 1850(1), pp. 97-106. (doi: 10.1016/j.bbagen.2014.10.003) (PMID:25316288)

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Abstract

Background: The North American wood frog, Rana sylvatica, is able to overcome subzero conditions through overwintering in a frozen state. Freezing imposes ischemic and oxidative stress on cells as a result of cessation of blood flow. Superoxide dismutases (SODs) catalyze the redox reaction involving the dismutation of superoxide (O2−radical dot) to molecular oxygen and hydrogen peroxide. Methods: The present study investigated the regulation of CuZnSOD and MnSOD kinetics as well as the transcript, protein and phosphorylation levels of purified enzyme from the muscle of control and frozen R. sylvatica. Results: CuZnSOD from frozen muscle showed a significantly higher Vmax (1.52 fold) in comparison to CuZnSOD from the muscle of control frogs. MnSOD from frozen muscle showed a significantly lower Km for O2−radical dot (0.66 fold) in comparison to CuZnSOD from control frogs. MnSOD from frozen frogs showed higher phosphorylation of serine (2.36 fold) and tyrosine (1.27 fold) residues in comparison to MnSOD from control animals. Susceptibility to digestion via thermolysin after incubation with increasing amount of urea (Cm) was tested, resulting in no significant changes for CuZnSOD, whereas a significant change in MnSOD stability was observed between control (2.53 M urea) and frozen (2.92 M urea) frogs. Expressions of CuZnSOD and MnSOD were quantified at both mRNA and protein levels in frog muscle, but were not significantly different. Conclusion: The physiological consequence of freeze-induced SOD modification appears to adjust SOD function in freezing frogs. General significance: Augmented SOD activity may increase the ability of R. sylvatica to overcome oxidative stress associated with ischemia.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Dawson, Dr Neal
Authors: Dawson, N. J., Katzenback, B. A., and Storey, K. B.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
College of Medical Veterinary and Life Sciences > School of Biodiversity, One Health & Veterinary Medicine
Journal Name:Biochimica et Biophysica Acta
Publisher:Elsevier
ISSN:0006-3002
ISSN (Online):1878-2434
Published Online:12 October 2014

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