Elongation Factor 2 Kinase Is Regulated by Proline Hydroxylation and Protects Cells during Hypoxia

• Published in: Molecular and cellular biology Vol. 35; no. 10; pp. 1788 - 1804
• Main Authors: Moore, Claire E. J., Mikolajek, Halina, Regufe da Mota, Sergio, Wang, Xuemin, Kenney, Justin W., Werner, Jörn M., Proud, Christopher G.
• Format: Journal Article
• Language: English
• Published: United States Taylor & Francis 01.05.2015; American Society for Microbiology
• Subjects: aerobiosis; Animals; calmodulin; Calmodulin - metabolism; Catalytic Domain; cell biology; Cell Hypoxia; Cells, Cultured; Elongation Factor 2 Kinase - chemistry; Elongation Factor 2 Kinase - metabolism; energy; Enzyme Activation; HCT116 Cells; HEK293 Cells; HeLa Cells; Humans; Hydroxylation; hypoxia; Mice; neurons; Neurons - enzymology; oxygen; Peptide Elongation Factor 2 - metabolism; peptide elongation factors; phosphorylation; Phosphorylation - drug effects; proline; Proline - metabolism; Prolyl Hydroxylases - metabolism; Prolyl-Hydroxylase Inhibitors - pharmacology; protein synthesis; therapeutics
• ISSN: 1098-5549; 0270-7306; 1098-5549
• DOI: 10.1128/MCB.01457-14

Protein synthesis, especially translation elongation, requires large amounts of energy, which is often generated by oxidative metabolism. Elongation is controlled by phosphorylation of eukaryotic elongation factor 2 (eEF2), which inhibits its activity and is catalyzed by eEF2 kinase (eEF2K), a calcium/calmodulin-dependent α-kinase. Hypoxia causes the activation of eEF2K and induces eEF2 phosphorylation independently of previously known inputs into eEF2K. Here, we show that eEF2K is subject to hydroxylation on proline-98. Proline hydroxylation is catalyzed by proline hydroxylases, oxygen-dependent enzymes which are inactivated during hypoxia. Pharmacological inhibition of proline hydroxylases also stimulates eEF2 phosphorylation. Pro98 lies in a universally conserved linker between the calmodulin-binding and catalytic domains of eEF2K. Its hydroxylation partially impairs the binding of calmodulin to eEF2K and markedly limits the calmodulin-stimulated activity of eEF2K. Neuronal cells depend on oxygen, and eEF2K helps to protect them from hypoxia. eEF2K is the first example of a protein directly involved in a major energy-consuming process to be regulated by proline hydroxylation. Since eEF2K is cytoprotective during hypoxia and other conditions of nutrient insufficiency, it may be a valuable target for therapy of poorly vascularized solid tumors.