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An enzymatic bridge between carbohydrate and amino acid metabolism: regulation of glutamate dehydrogenase by reversible phosphorylation in a severe hypoxia-tolerant crayfish.
- Source :
-
Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology [J Comp Physiol B] 2012 Apr; Vol. 182 (3), pp. 331-40. Date of Electronic Publication: 2011 Nov 11. - Publication Year :
- 2012
-
Abstract
- Glutamate dehydrogenase (GDH) (EC 1.4.1.3) is a crucial enzyme involved in bridging two metabolic pathways, gating the use of glutamate for either amino acid metabolism, or carbohydrate metabolism. The present study investigated GDH from tail muscle of the freshwater crayfish Orconectes virilis exploring changes to kinetic properties, phosphorylation levels and structural stability between two forms of the enzyme (aerobic control and 20-h severe hypoxic). Evidence indicated that GDH was converted to a high phosphate form under oxygen limitation. ProQ Diamond phosphoprotein staining showed a 42% higher bound phosphate content on GDH from muscle of severely hypoxic crayfish compared with the aerobic form, and treatment of this GDH with commercial phosphatase (alkaline phosphatase), and treatments that stimulated the activities of different endogenous protein phosphatases (stimulating PP1 + PP2A, PP2B, and PP2C) yielded significant increases in the fold activation by ADP of GDH from both control and severe hypoxic conditions. By contrast, stimulation of the activities of endogenous protein kinases (AMPK, PKA or CaMK) significantly reduced the ADP fold activation from control animals. The physiological consequence of severe hypoxia-induced GDH phosphorylation may be to suppress GDH activity under low oxygen, shutting off this critical bridge point between two metabolic pathways.
- Subjects :
- Analysis of Variance
Animals
Astacoidea enzymology
Blotting, Western
Cell Hypoxia physiology
Muscle, Skeletal metabolism
Phosphoric Monoester Hydrolases
Phosphorylation
Amino Acids metabolism
Astacoidea physiology
Carbohydrate Metabolism physiology
Glutamate Dehydrogenase metabolism
Metabolic Networks and Pathways physiology
Subjects
Details
- Language :
- English
- ISSN :
- 1432-136X
- Volume :
- 182
- Issue :
- 3
- Database :
- MEDLINE
- Journal :
- Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology
- Publication Type :
- Academic Journal
- Accession number :
- 22076534
- Full Text :
- https://doi.org/10.1007/s00360-011-0629-4