Co-Crystal Structures of PKG Iβ (92–227) with cGMP and cAMP Reveal the Molecular Details of Cyclic-Nucleotide Binding

Cyclic GMP-dependent protein kinases (PKGs) are central mediators of the NO-cGMP signaling pathway and phosphorylate downstream substrates that are crucial for regulating smooth muscle tone, platelet activation, nociception and memory formation. As one of the main receptors for cGMP, PKGs mediate most of the effects of cGMP elevating drugs, such as nitric oxide-releasing agents and phosphodiesterase inhibitors which are used for the treatment of angina pectoris and erectile dysfunction, respectively. configuration, with a conserved threonine residue anchoring both cyclic phosphate and guanine moieties. The structure of CNBD-A in the absence of bound cyclic nucleotide was similar to that of the cyclic nucleotide bound structures. Surprisingly, isothermal titration calorimetry experiments demonstrated that CNBD-A binds both cGMP and cAMP with a relatively high affinity, showing an approximately two-fold preference for cGMP. conformation through its interaction with Thr193 and an unusual cis-peptide forming residues Leu172 and Cys173. Although these studies provide the first structural insights into cyclic nucleotide binding to PKG, our ITC results show only a two-fold preference for cGMP, indicating that other domains are required for the previously reported cyclic nucleotide selectivity

Exploring the structural basis of conformational heterogeneity and autoinhibition of human cGMP-specific protein kinase Iα through computational modelling and molecular dynamics simulations.

Protein kinase Iα (PKGIα) is a pivotal cyclic guanosine monophosphate (cGMP) signalling protein. Major steps related to the structural plasticity of PKGIα have been inferred but the structural aspects of the auto-inhibition and multidomain tertiary organization of human PKGIα in active and inactive form are not clear. Here we combine computational comparative modelling, protein-protein docking and molecular dynamics (MD) simulations to investigate structural details of the repressed state of the catalytic domain of PKGIα. Exploration of the potential inhibitory conformation of the auto-inhibitory domain (AI) within the catalytic cleft reveals that the pseudo-substrate motif binds with residues of the glycine rich loop and substrate-binding lobe. Dynamic changes as a result of coupling of the catalytic and AI domains are also investigated. The three-dimensional homodimeric models of PKGIα in the active and inactive state indicate that PKGIα in its inactive-state attains a compact globular structure where cyclic nucleotide binding (CNB-A/B) domains are buried, whereas the catalytic domains are inaccessible with their substrate-binding pockets facing the N-terminal of CNB-A. Contrary to this, the active-state model of PKGIα shows an extended conformation where CNB-A/B domains are slightly rearranged and the catalytic domains of homodimer flanking the C-terminal with their substrate binding lobes free to entrap downstream proteins. These findings are consistent with previously reported static images of the multidomain organization of PKGIα. Structural insights pertaining to the conformational heterogeneity and auto-inhibition of PKGIα provided in this study may help to understand the dynamics-driven effective regulation of PKGIα

Спроби розв’язання Радою Народних Міністрів Української Народної Республіки земельного питання у березні-квітні 1918 року

У статті розглядається діяльність РНМ УНР із реформування земельних відносин в Україні, реалізації тимчасового земельного закону, вирішення питання засіву землі весною 1918 р.В статье рассматривается деятельность СНМ УНР по реформированию земельных отношений в Украине, реализации временного земельного закона, решение вопроса засева земли весной 1918 г.In the article activity of CFМ of UNR is examined from reformation of the landed relations in Ukraine, realization of the temporal landed law, decision of sowing of the land in spring 1918