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Crystal structure of cGMP-dependent protein kinase Iβ cyclic nucleotide-binding-B domain : Rp-cGMPS complex reveals an apo-like, inactive conformation

  • Author(s): Campbell, JC
  • VanSchouwen, B
  • Lorenz, R
  • Sankaran, B
  • Herberg, FW
  • Melacini, G
  • Kim, C
  • et al.
Abstract

� 2016 Federation of European Biochemical Societies The R-diastereomer of phosphorothioate analogs of cGMP, Rp-cGMPS, is one of few known inhibitors of cGMP-dependent protein kinase I (PKG I); however, its mechanism of inhibition is currently not fully understood. Here, we determined the crystal structure of the PKG Iβ cyclic nucleotide-binding domain (PKG Iβ CNB-B), considered a ‘gatekeeper’ for cGMP activation, bound to Rp-cGMPS at 1.3 �. Our structural and NMR data show that PKG Iβ CNB-B bound to Rp-cGMPS displays an apo-like structure with its helical domain in an open conformation. Comparison with the cAMP-dependent protein kinase regulatory subunit (PKA RIα) showed that this conformation resembles the catalytic subunit-bound inhibited state of PKA RIα more closely than the apo or Rp-cAMPS-bound conformations. These results suggest that Rp-cGMPS inhibits PKG I by stabilizing the inactive conformation of CNB-B.

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