A new autoinhibited kinase conformation reveals a salt-bridge switch in kinase activation.
In the structure of autoinhibited EphA2 tyrosine kinase reported herein, we have captured the entire activation segment, revealing a previously unknown role of the conserved Arg762 in kinase autoinhibition by interacting with the essential Mg(2+)-chelating Asp757. While it is well known that this Arg residue is involved in an electrostatic interaction with the phospho-residue of the activation loop to stabilize the active conformation, our structure determination revealed a new role for the Arg, acting as a switch between the autoinhibited and activated conformations. Mutation of Arg762 to Ala in EphA2 sensitized Mg(2+) response, resulting in enhanced kinase catalytic activity and Mg(2+) cooperativity. Furthermore, mutation of the corresponding Arg/Lys to Ala in PKA and p38MAPK also exhibited similar behavior. This new salt bridge-mediated switch may thus be an important mechanism of activation on a broader scope for kinases which utilize autophosphorylation.
College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Qiang
Q
Wei
College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Shaoyuan
S
Yang
College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Dan
D
Li
College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Xiaoying
X
Zhang
College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Jimin
J
Zheng
College of Chemistry, Beijing Normal University, Beijing, 100875, China.|Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, K7L 3N6, Canada.
Zongchao
Z
Jia
D018360:Crystallography, X-Ray; D017868:Cyclic AMP-Dependent Protein Kinases / Q000235:genetics / Q000378:metabolism; D057075:Enzyme Assays; D006801:Humans; D007700:Kinetics; D008274:Magnesium / Q000737:chemistry / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D017434:Protein Structure, Tertiary; D036104:Receptor, EphA2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism
D011994:Recombinant Proteins; D036104:Receptor, EphA2; D017868:Cyclic AMP-Dependent Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D008274:Magnesium