title: Crystal Structure of PKG I:cGMP Complex Reveals a cGMP-Mediated Dimeric Interface that Facilitates cGMP-Induced Activation.
abstract: 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.
authors.affiliation: Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Biochemistry, University of Kassel, Kassel, Hesse 34132, Germany.
authors.forename: Jeong Joo
authors.initials: JJ
authors.lastname: Kim
authors.affiliation: Department of Biochemistry, University of Kassel, Kassel, Hesse 34132, Germany.
authors.forename: Robin
authors.initials: R
authors.lastname: Lorenz
authors.affiliation: 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.
authors.forename: Stefan T
authors.initials: ST
authors.lastname: Arold
authors.affiliation: Department of Pharmacology, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Albert S
authors.initials: AS
authors.lastname: Reger
authors.affiliation: Berkeley Center for Structural Biology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Banumathi
authors.initials: B
authors.lastname: Sankaran
authors.affiliation: Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA.
authors.forename: Darren E
authors.initials: DE
authors.lastname: Casteel
authors.affiliation: Department of Biochemistry, University of Kassel, Kassel, Hesse 34132, Germany.
authors.forename: Friedrich W
authors.initials: FW
authors.lastname: Herberg
authors.affiliation: 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. Electronic address: ckim@bcm.edu.
authors.forename: Choel
authors.initials: C
authors.lastname: Kim
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D006152:Cyclic GMP / Q000737:chemistry / Q000378:metabolism*; D062965:Cyclic GMP-Dependent Protein Kinase Type I / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D062105:Molecular Docking Simulation; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D062965:Cyclic GMP-Dependent Protein Kinase Type I; D006152:Cyclic GMP
keywords: NO-cGMP signaling; allosteric activation; cGMP-dependent protein kinase; crystal structure; cyclic nucleotide-binding domain; second messengers; small-angle X-ray scattering