title: The gatekeeper residue controls autoactivation of ERK2 via a pathway of intramolecular connectivity.
abstract: Studies of protein kinases have identified a "gatekeeper" residue, which confers selectivity for binding nucleotides and small-molecule inhibitors. We report that, in the MAP kinase ERK2, mutations at the gatekeeper residue unexpectedly lead to autoactivation due to enhanced autophosphorylation of regulatory Tyr and Thr sites within the activation lip that control kinase activity. This occurs through an intramolecular mechanism, indicating that the gatekeeper residue indirectly constrains flexibility at the activation lip, precluding access of the phosphoacceptor residues to the catalytic base. Other residues that interact with the gatekeeper site to form a hydrophobic cluster in the N-terminal domain also cause autoactivation when mutated. Hydrogen-exchange studies of a mutant within this cluster reveal perturbations in the conserved DFG motif, predicting a route for side chain connectivity from the hydrophobic cluster to the activation lip. Mutations of residues along this route support this model, explaining how information about the gatekeeper residue identity can be transmitted to the activation lip. Thus, an N-terminal hydrophobic cluster that includes the gatekeeper forms a novel structural unit, which functions to maintain the "off" state of ERK2 before cell signal activation.
authors.affiliation: Department of Chemistry and Biochemistry, Howard Hughes Medical Institute, University of Colorado, Boulder, CO 80309, USA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Emrick
authors.forename: Thomas
authors.initials: T
authors.lastname: Lee
authors.forename: Paul J
authors.initials: PJ
authors.lastname: Starkey
authors.forename: Marc C
authors.initials: MC
authors.lastname: Mumby
authors.forename: Katheryn A
authors.initials: KA
authors.lastname: Resing
authors.forename: Natalie G
authors.initials: NG
authors.lastname: Ahn
mesh_terms: D000818:Animals; D004789:Enzyme Activation; D005973:Glutamine / Q000235:genetics / Q000378:metabolism; D057927:Hydrophobic and Hydrophilic Interactions; D020935:MAP Kinase Signaling System; D019950:Mitogen-Activated Protein Kinase 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D051381:Rats
chemical_list: D005973:Glutamine; D019950:Mitogen-Activated Protein Kinase 1