Identification and confirmation of 14-3-3 ζ as a novel target of ginsenosides in brain tissues

Background: Ginseng can help regulate brain excitability, promote learning and memory, and resist cerebral ischemia in the central nervous system. Ginsenosides are the major effective compounds of Ginseng, but their protein targets in the brain have not been determined. Methods: We screened proteins that interact with the main components of ginseng (ginsenosides) by affinity chromatography and identified the 14-3-3 zeta protein as a potential target of ginsenosides in brain tissues. Results: Biolayer interferometry (BLI) analysis showed that 20(S)-protopanaxadiol (PPD), a ginseng saponin metabolite, exhibited the highest direct interaction to the 14-3-3 zeta protein. Subsequently, BLI kinetics analysis and isothermal titration calorimetry (ITC) assay showed that PPD specifically bound to the 14-3-3 zeta protein. The cocrystal structure of the 14-3-3 zeta protein-PPD complex showed that the main interactions occurred between the residues R56, R127, and Y128 of the 14-3-3 zeta protein and a portion of PPD. Moreover, mutating any of the above residues resulted in a significant decrease of affinity between PPD and the 14-3-3 zeta protein. Conclusion: Our results indicate the 14-3-3 zeta protein is the target of PPD, a ginsenoside metabolite. Crystallographic and mutagenesis studies suggest a direct interaction between PPD and the 14-3-3 zeta protein. This finding can help in the development of small-molecular compounds that bind to the 14-3-3 zeta protein on the basis of the structure of dammarane-type triterpenoid. (C) 2021 The Korean Society of Ginseng. Publishing services by Elsevier B.V.

Automated summary

The study identified a direct interaction between the ginsenoside metabolite PPD and the 14-3-3 zeta protein in brain tissues, with mutations in specific residues of the protein leading to decreased affinity with PPD. This finding could aid in the development of small-molecular compounds that bind to the 14-3-3 zeta protein based on dammarane-type triterpenoid structure.