Two potential fish glycerol-3-phosphate phosphatases
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Winter-acclimated rainbow smelt (Osmerus mordax Mitchill) produce high levels of glycerol as an antifreeze. A common pathway to glycerol involves the enzyme glycerol-3-phosphate phosphatase (GPP), but no GPP has yet been identified in fish or any other animal. Here, two phosphatases assembled from existing EST libraries (from winter-acclimated smelt and cold-acclimated smelt hepatocytes) were found to resemble a glycerol-associated phosphatase from a glycerol-producing alga, Dunaliella salina, and a recently discovered GPP from a bacterium, Mycobacterium tuberculosis. Recombinant proteins were generated and were found to have GPP activity on the order of a few μMol Pi/mg enzyme/min. The two enzymes have acidic pH optima (~5.5) similar to that previously determined for GPP activity in liver tissue, with about 1/3 of their peak activities at neutral pH. The two enzymes appear to account for the GPP activity of smelt liver, but due to their reduced activities at neutral pH, their contributions to glycerol production in vivo remain unclear. Similar enzymes may be active in a glycerol-producing insect, Dendroctonus ponderosae.
KeywordsPhosphoserine phosphatase serB Osmerus mordax Dunaliella salina Mycobacterium tuberculosis
I thank William Driedzic and Delphine Ditlecadet for helpful discussion that led to the present study. I thank the School of Life Sciences, University of Nevada, Las Vegas, for providing laboratory resources for this study.
- Keeling CI et al (2013) Draft genome of the mountain pine beetle, Dendroctonus ponderosae Hopkins, a major forest pest. Genome Biol 14:R27Google Scholar
- Pahlman AK, Granath K, Ansell R, Hohmann S, Adler L (2001) The yeast glycerol 3-phosphatases Gpp1p and Gpp2p are required for glycerol biosynthesis and differentially involved in the cellular responses to osmotic, anaerobic, and oxidative stress. J Biol Chem 276:3555–3563CrossRefPubMedGoogle Scholar
- Roberts SB, Hauser L, Seeb LW, Seeb JE (2012) Development of genomic resources for pacific herring through targeted transcriptome pyrosequencing. PLoS ONE 7:e30908Google Scholar
- Storey KB, Storey JM (2012) Insect cold hardiness: metabolic, gene, and protein adaptation. Can J Zool 90:456–475Google Scholar