title: A conserved loop in the catalytic domain of eukaryotic elongation factor 2 kinase plays a key role in its substrate specificity.
abstract: Eukaryotic elongation factor 2 kinase (eEF2K) is the best-characterized member of the α-kinase family. Within this group, only eEF2K and myosin heavy chain kinases (MHCKs) have known substrates. Here we have studied the roles of specific residues, selected on the basis of structural data for MHCK A and TRPM7, in the function of eEF2K. Our data provide the first information regarding the basis of the substrate specificity of α-kinases, in particular the roles of residues in the so-called N/D loop, which appears to occupy a position in the structure of α-kinases similar to that of the activation loop in other kinases. Several mutations in the EEF2K gene occur in tumors, one of which (Arg303Cys) is at a highly conserved residue in the N/D loop. This mutation greatly enhances eEF2K activity and may be cytoprotective. Our data support the concept that the major autophosphorylation site (Thr348 in eEF2K) docks into a binding pocket to help create the kinase-competent conformation. This is similar to the situation for MHCK A and is consistent with this being a common feature of α-kinases.
authors.affiliation: Centre for Biological Sciences, Highfield Campus, University of Southampton, Southampton, United Kingdom.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Moore
authors.affiliation: Centre for Biological Sciences, Highfield Campus, University of Southampton, Southampton, United Kingdom.
authors.forename: Sergio
authors.initials: S
authors.lastname: Regufe da Mota
authors.affiliation: Centre for Biological Sciences, Highfield Campus, University of Southampton, Southampton, United Kingdom.
authors.forename: Halina
authors.initials: H
authors.lastname: Mikolajek
authors.affiliation: Centre for Biological Sciences, Highfield Campus, University of Southampton, Southampton, United Kingdom C.G.Proud@soton.ac.uk.
authors.forename: Christopher G
authors.initials: CG
authors.lastname: Proud
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics; D001665:Binding Sites; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000737:chemistry; D020134:Catalytic Domain; D017124:Conserved Sequence; D054736:Elongation Factor 2 Kinase / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D009369:Neoplasms / Q000235:genetics / Q000473:pathology; D010766:Phosphorylation; D010769:Phosphothreonine / Q000378:metabolism; D011485:Protein Binding; D017433:Protein Structure, Secondary; D015800:Protozoan Proteins / Q000737:chemistry; D040681:Structural Homology, Protein; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D000596:Amino Acids; D015800:Protozoan Proteins; D010769:Phosphothreonine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D054736:Elongation Factor 2 Kinase; C033142:myosin-heavy-chain kinase
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