6c0u
Crystal structure of cAMP-dependent protein kinase Calpha subunit bound with N46
Structural highlights
FunctionKAPCA_HUMAN Phosphorylates a large number of substrates in the cytoplasm and the nucleus. Regulates the abundance of compartmentalized pools of its regulatory subunits through phosphorylation of PJA2 which binds and ubiquitinates these subunits, leading to their subsequent proteolysis. Phosphorylates CDC25B, ABL1, NFKB1, CLDN3, PSMC5/RPT6, PJA2, RYR2, RORA, TRPC1 and VASP. RORA is activated by phosphorylation. Required for glucose-mediated adipogenic differentiation increase and osteogenic differentiation inhibition from osteoblasts. Involved in the regulation of platelets in response to thrombin and collagen; maintains circulating platelets in a resting state by phosphorylating proteins in numerous platelet inhibitory pathways when in complex with NF-kappa-B (NFKB1 and NFKB2) and I-kappa-B-alpha (NFKBIA), but thrombin and collagen disrupt these complexes and free active PRKACA stimulates platelets and leads to platelet aggregation by phosphorylating VASP. Prevents the antiproliferative and anti-invasive effects of alpha-difluoromethylornithine in breast cancer cells when activated. RYR2 channel activity is potentiated by phosphorylation in presence of luminal Ca(2+), leading to reduced amplitude and increased frequency of store overload-induced Ca(2+) release (SOICR) characterized by an increased rate of Ca(2+) release and propagation velocity of spontaneous Ca(2+) waves, despite reduced wave amplitude and resting cytosolic Ca(2+). TRPC1 activation by phosphorylation promotes Ca(2+) influx, essential for the increase in permeability induced by thrombin in confluent endothelial monolayers. PSMC5/RPT6 activation by phosphorylation stimulates proteasome. Regulates negatively tight junction (TJs) in ovarian cancer cells via CLDN3 phosphorylation. NFKB1 phosphorylation promotes NF-kappa-B p50-p50 DNA binding. Involved in embryonic development by down-regulating the Hedgehog (Hh) signaling pathway that determines embryo pattern formation and morphogenesis. Isoform 2 phosphorylates and activates ABL1 in sperm flagellum to promote spermatozoa capacitation. Prevents meiosis resumption in prophase-arrested oocytes via CDC25B inactivation by phosphorylation. May also regulate rapid eye movement (REM) sleep in the pedunculopontine tegmental (PPT). Phosphorylates APOBEC3G and AICDA.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] Publication Abstract from PubMedActivation of PKG Ialpha in nociceptive neurons induces a long-term hyperexcitability that causes chronic pain. Recently, a derivative of the fungal metabolite balanol, N46, has been reported to inhibit PKG Ialpha with high potency and selectivity and attenuates thermal hyperalgesia and osteoarthritic pain. Here, we determined co-crystal structures of the PKG Ialpha C-domain and cAMP-dependent protein kinase (PKA) Calpha, each bound with N46, at 1.98 A and 2.65 A, respectively. N46 binds the active site with its external phenyl ring specifically interacting with the glycine-rich loop and the alphaC helix. Phe371 at the PKG Ialpha glycine-rich loop is oriented parallel to the phenyl ring of N46, forming a strong pi-stacking interaction, while the analogous Phe54 in PKA Calpha rotates 30 masculine and forms a weaker interaction. Structural comparison revealed that steric hindrance between the preceding Ser53 and the propoxy group of the phenyl ring may explain the weaker interaction with PKA Calpha. The analogous Gly370 in PKG Ialpha, however, causes little steric hindrance with Phe371. Moreover, Ile406 on the alphaC helix forms a hydrophobic interaction with N46 while its counterpart in PKA, Thr88, does not. Substituting these residues in PKG Ialpha with those in PKA Calpha increases its IC50 values for N46 whereas replacing these residues in PKA Calpha with those in PKG Ialpha reduces the IC50, consistent with our structural findings. In conclusion, our results explain the structural basis for N46-mediated selective inhibition of human PKG Ialpha and provide a starting point for structure-guided design of selective PKG Ialpha inhibitors. Structural basis for selective inhibition of human PKG Ialpha by the balanol-like compound N46.,Qin L, Sankaran B, Aminzai S, Casteel D, Kim C J Biol Chem. 2018 May 16. pii: RA118.002427. doi: 10.1074/jbc.RA118.002427. PMID:29769318[12] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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