Cyclic guanosine monophosphate (cGMP)-dependent protein kinase (PKG) is a key regulator of smooth muscle and vascular tone and represents an important drug target for treating hypertensive diseases and erectile dysfunction.
Despite its importance, its activation mechanism is not fully understood. To understand the activation mechanism, we determined a 2.5 Å crystal structure of the PKG I regulatory (R) domain bound with cGMP, which represents the activated state. Although we used a monomeric domain for crystallization, the structure reveals that two R domains form a symmetric dimer where the cGMP bound at high-affinity pockets provide critical dimeric contacts. Small-angle X-ray scattering and mutagenesis support this dimer model, suggesting that the dimer interface modulates kinase activation. Finally, structural comparison with the homologous cyclic AMP-dependent protein kinase reveals that PKG is drastically different from protein kinase A in its active conformation, suggesting a novel activation mechanism for PKG.
Structure (London, England : 1993). 2016 Apr 05 [Epub ahead of print]
Jeong Joo Kim, Robin Lorenz, Stefan T Arold, Albert S Reger, Banumathi Sankaran, Darren E Casteel, Friedrich W Herberg, Choel Kim
Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Biochemistry, University of Kassel, Kassel, Hesse 34132, Germany., Department of Biochemistry, University of Kassel, Kassel, Hesse 34132, Germany., King Abdullah University of Science and Technology (KAUST), Computational Bioscience Research Center, Division of Biological and Environmental Sciences and Engineering, Thuwal 23955-6900, Saudi Arabia., Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA., Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA., Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA., Department of Biochemistry, University of Kassel, Kassel, Hesse 34132, Germany., Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA; Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, USA.