Crystal Structure of cGMP-Dependent Protein Kinase Reveals Novel Site of Interchain Communication

Department of Pharmacology, College of Medicine, University of Vermont, Burlington, VT 05405, USA.
Structure (Impact Factor: 5.62). 09/2011; 19(9):1317-27. DOI: 10.1016/j.str.2011.06.012
Source: PubMed


The cGMP-dependent protein kinase (PKG) serves as an integral component of second messenger signaling in a number of biological contexts including cell differentiation, memory, and vasodilation. PKG is homodimeric and large conformational changes accompany cGMP binding. However, the structure of PKG and the molecular mechanisms associated with protomer communication following cGMP-induced activation remain unknown. Here, we report the 2.5 Å crystal structure of a regulatory domain construct (aa 78-355) containing both cGMP binding sites of PKG Iα. A distinct and segregated architecture with an extended central helix separates the two cGMP binding domains. Additionally, a previously uncharacterized helical domain (switch helix) promotes the formation of a hydrophobic interface between protomers. Mutational disruption of this interaction in full-length PKG implicates the switch helix as a critical site of dimer communication in PKG biology. These results offer new structural insight into the mechanism of allosteric PKG activation.

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    • "interventions that prevent either of their formation limiting PKG signaling responses to oxidants . Studies with metal ion - induced oxidation identified the intraprotein disulfides , whilst those with H 2 O 2 ( Landgraf et al . , 1991 ; Osborne et al . , 2011 ) , nitrosocysteine ( Burgoyne and Eaton , 2009 ) , or H 2 S ( Landgraf et al . , 1991 ; Osborne et al . , 2011 ) identified the interprotein disulfide . It is possible that each of these oxidants simultaneously induced all of the several disulfides that can form , but they were not reported in some studies because they could not be determined or were not specifically assessed ."
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    • "The cAMP-dependent protein kinases (PKAs) and cGMP-dependent protein kinases (PKGs) are part of the same sub-family of kinase domains [36] and have similar domain components, and quaternary structure [66]. PKG is composed of a single protein with cGMP binding and protein-kinase activity. "
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    • "Specifically , a transitional domain found only in the type I isoforms, called the SW helix, bridges between regulatory and catalytic domains and has Fig. 7. The structures of the regulatory domains of holo PKG1α (green) and apo PKA:RIα (black) with the A-sites for nucleotide binding aligned using a PyMOL all-atom alignment (residues PKG:78–198, PKA:110–230) [17] [26]. a) A side view showing the bowing of the B/C helix associated with PKG. "
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