Journal of Biological Chemistry
Volume 290, Issue 34, 21 August 2015, Pages 20649-20659
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Signal Transduction
Crystal Structure of G Protein-coupled Receptor Kinase 5 in Complex with a Rationally Designed Inhibitor*Crystal Structure of the GRK5·CCG215022 Complex

https://doi.org/10.1074/jbc.M115.647370Get rights and content
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G protein-coupled receptor kinases (GRKs) regulate cell signaling by initiating the desensitization of active G protein-coupled receptors. The two most widely expressed GRKs (GRK2 and GRK5) play a role in cardiovascular disease and thus represent important targets for the development of novel therapeutic drugs. In the course of a GRK2 structure-based drug design campaign, one inhibitor (CCG215022) exhibited nanomolar IC50 values against both GRK2 and GRK5 and good selectivity against other closely related kinases such as GRK1 and PKA. Treatment of murine cardiomyocytes with CCG215022 resulted in significantly increased contractility at 20-fold lower concentrations than paroxetine, an inhibitor with more modest selectivity for GRK2. A 2.4 Å crystal structure of the GRK5·CCG215022 complex was determined and revealed that the inhibitor binds in the active site similarly to its parent compound GSK180736A. As designed, its 2-pyridylmethyl amide side chain occupies the hydrophobic subsite of the active site where it forms three additional hydrogen bonds, including one with the catalytic lysine. The overall conformation of the GRK5 kinase domain is similar to that of a previously determined structure of GRK6 in what is proposed to be its active state, but the C-terminal region of the enzyme adopts a distinct conformation. The kinetic properties of site-directed mutants in this region are consistent with the hypothesis that this novel C-terminal structure is representative of the membrane-bound conformation of the enzyme.

enzyme inhibitor
plasma membrane
protein kinase
site-directed mutagenesis
x-ray crystallography
G protein-coupled receptor kinase
crystallography
membrane targeting
rational drug design

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The atomic coordinates and structure factors (code 4WNK) have been deposited in the Protein Data Bank (http://wwpdb.org/).

*

This work was supported, in whole or in part, by National Institutes of Health Grants HL071818 and HL086865 (to J. T.) and was conducted in part at Temple University School of Medicine (to W. J. K.) supported by National Institutes of Health Grants R37 HL061690, P01 HL075443 (Project 2), P01 HL108806 (Project 3) and P01 HL091799. This work was also supported by American Heart Association Grant N014938 (to K T. H.). The authors declare that they have no conflicts of interest with the contents of this article.

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