title: Molecular Mechanism for the Control of Eukaryotic Elongation Factor 2 Kinase by pH: Role in Cancer Cell Survival.
abstract: Acidification of the extracellular and/or intracellular environment is involved in many aspects of cell physiology and pathology. Eukaryotic elongation factor 2 kinase (eEF2K) is a Ca(2+)/calmodulin-dependent kinase that regulates translation elongation by phosphorylating and inhibiting eEF2. Here we show that extracellular acidosis elicits activation of eEF2K in vivo, leading to enhanced phosphorylation of eEF2. We identify five histidine residues in eEF2K that are crucial for the activation of eEF2K during acidosis. Three of them (H80, H87, and H94) are in its calmodulin-binding site, and their protonation appears to enhance the ability of calmodulin to activate eEF2K. The other two histidines (H227 and H230) lie in the catalytic domain of eEF2K. We also identify His108 in calmodulin as essential for activation of eEF2K. Acidification of cancer cell microenvironments is a hallmark of malignant solid tumors. Knocking down eEF2K in cancer cells attenuated the decrease in global protein synthesis when cells were cultured at acidic pH. Importantly, activation of eEF2K is linked to cancer cell survival under acidic conditions. Inhibition of eEF2K promotes cancer cell death under acidosis.
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom South Australian Health & Medical Research Institute, Adelaide, Australia.
authors.forename: Jianling
authors.initials: J
authors.lastname: Xie
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Halina
authors.initials: H
authors.lastname: Mikolajek
authors.affiliation: Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, BC, Canada.
authors.forename: Craig R
authors.initials: CR
authors.lastname: Pigott
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Kelly J
authors.initials: KJ
authors.lastname: Hooper
authors.affiliation: Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom.
authors.forename: Toby
authors.initials: T
authors.lastname: Mellows
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Moore
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Hafeez
authors.initials: H
authors.lastname: Mohammed
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom.
authors.forename: Jörn M
authors.initials: JM
authors.lastname: Werner
authors.affiliation: Cancer Sciences Unit, Faculty of Medicine, University of Southampton, Southampton, United Kingdom NIHR Experimental Cancer Medicine Centre Southampton, Southampton, United Kingdom.
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Thomas
authors.affiliation: Centre for Biological Sciences, University of Southampton, Southampton, United Kingdom South Australian Health & Medical Research Institute, Adelaide, Australia Department of Biochemistry & Molecular Biology, University of British Columbia, Vancouver, BC, Canada Department of Molecular & Cellular Biology, School of Biological Sciences, University of Adelaide, Adelaide, Australia christopher.proud@sahmri.com.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Proud
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D020134:Catalytic Domain; D002460:Cell Line; D002470:Cell Survival; D054736:Elongation Factor 2 Kinase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004789:Enzyme Activation; D015972:Gene Expression Regulation, Neoplastic; D045325:HCT116 Cells; D057809:HEK293 Cells; D006639:Histidine / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D051379:Mice; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology
chemical_list: D002147:Calmodulin; D006639:Histidine; C517689:EEF2K protein, human; C517690:Eef2k protein, mouse; D054736:Elongation Factor 2 Kinase