Structural Basis of Cyclic Nucleotide Selectivity in cGMP-dependent Protein Kinase II.

Author(s): Campbell, JC; Kim, JJ; Li, KY; Huang, GY; Reger, AS; Matsuda, S; Sankaran, B; Link, TM; Yuasa, K; Ladbury, JE; Casteel, DE; Kim, C | Abstract: © 2016, American Society for Biochemistry and Molecular Biology Inc. All rights reserved. Membrane-bound cGMP-dependent protein kinase(PKG) II is a key regulator of bone growth, renin secretion, and memory formation. Despite its crucial physiological roles, little is known about its cyclic nucleotideselectivity mechanism due to a lack of structural information. Here, we find that the C-terminal cyclic nucleotidebinding (CNB-B) domain of PKGII binds cGMP with higher affinity and selectivity when compared with its N-terminal CNB (CNB-A) domain. To understand the structural basis of cGMP selectivity, we solved co-crystal structures of the CNB domains with cyclic nucleotides. Our structures combined with mutagenesis demonstrate that the guanine-specific contacts at Asp-412 and Arg-415 of the αC-helix of CNB-B are crucial for cGMP selectivity and activation of PKG II. Structural comparison with the cGMP selective CNB domains of human PKG I and Plasmodium falciparum PKG (PfPKG) shows different contacts with the guaninemoiety, revealing a unique cGMP selectivity mechanism for PKG II.