9p74 | pdb_00009p74
Crystal Structure of cGMP-dependent protein kinase from Plasmodium vivax in complex with inhibitor RUBP-61
Structural highlights
FunctionKGP_PLAVS Serine/threonine protein kinase which acts as a downstream effector of the second messenger cGMP. Controls the release of Ca(2+) from intracellular stores by regulating phosphoinositide biosynthesis. Ca(2+) signals are essential for merozoite and sporozoite invasion and egress from host hepatocytes and erythrocytes, and, in the mosquito vector, for gametocyte activation, and ookinete and sporozoite motility (By similarity). During the host liver stage, regulates the initial invasion of host hepatocytes by sporozoites by regulating sporozoite motility and microneme exocytosis. Following parasite development in the hepatocytes, required for the release of merosomes, a vesicle containing the mature merozoites (By similarity). During the asexual blood stage, required for the progression from schizont to the ring stage following merozoite invasion of host erythrocytes and for merozoite egress. Regulates merozoite egress by promoting the release of exonemes and micronemes which contain proteins essential for egress. Phosphorylates CDPK1 predominantly at the late schizont stage; phosphorylation at 'Ser-64' regulates CDPK1 protein-protein interaction and phosphorylation at 'Thr-231' may regulate CDPK1 kinase activity. In the mosquito vector, required for the initiation of gametogenesis induced by xanthurenic acid, specifically the gametocyte differentiation from the crescent-shaped form to the spherical form (By similarity). Required for the gliding motility of ookinetes to reach and penetrate the midgut epithelium by promoting Ca(2+)-mediated activation of CDPK1 and CDPK4. Also required for microneme secretion in ookinete by promoting Ca(2+)-mediated activation of CDPK3 (By similarity).[UniProtKB:A0A509AKL0][UniProtKB:Q8I719] Publication Abstract from PubMedMalaria remains a global health threat exacerbated by emerging resistance to antimalarial therapies and insecticides, climate-driven outbreaks, and limited chemoprotective options. Here, we report the characterization of RUPB-61, the first orally bioavailable inhibitor of Plasmodium falciparum cGMP-dependent protein kinase (PfPKG). RUPB-61 prevents infection by P. falciparum and P. cynomolgi sporozoites, including the formation of hypnozoites by the latter. A single oral dose blocks liver infection by P. berghei sporozoites in vivo, demonstrating efficacy consistent with further development as a once-weekly prophylaxis based on pharmacokinetic modeling. The compound retains activity against field isolates resistant to chloroquine, mefloquine, cycloguanil, sulfadoxine and pyrimethamine, suggesting low likelihood of cross-resistance to existing antimalarials. Structural studies and free energy-based modeling guided-compound design prospectively validated the predictive accuracy of an in silico model of PfPKG interactions with this chemotype. While selectivity profiling identified off-target activity against human kinases, structural modeling provides a clear path for optimization. These results establish PfPKG inhibitors as promising candidates for chemoprevention and support further preclinical development of the RUPB-61 chemotype. An orally available PfPKG inhibitor blocks Plasmodium's infection of the liver.,Dhiyebi H, Mbaye A, Thaniana A, Gilleran J, Eck T, Ashraf K, Kudyba K, Fan H, Seibold S, Battaile KP, Siekierka J, Johnson E, Roth A, De Rocher A, Lovell S, Miller EB, Roberge JY, Bhanot P PLoS Pathog. 2026 Jul 30;22(7):e1014322. doi: 10.1371/journal.ppat.1014322. , eCollection 2026 Jul. PMID:42531257[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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