Effect of double mutations K214/A-E215/Q of FRATide on GSK3β: insights from molecular dynamics simulation and normal...

Glycogen synthase kinase 3β (GSK3β) is a multifunctional serine/threonine protein kinase that is involved in several biological processes including insulin and Wnt signaling pathways. The Wnt signaling via FRAT-mediated displacement of axin inhibits GSK3β activity toward non-primed substrates without affecting its activity toward primed substrates. Herein, molecular dynamics simulation, molecular mechanics generalized Born/surface area (MM_GBSA) calculation, and normal mode analysis are performed to explore the structural influence of the double mutations K214/A-E215/Q of FRATide on the GSK3β-FRATide complex. The results reveal that the priming phosphate-binding site, the primed substrate-binding site, the alignment of the critical active site residues in the ATP-binding site, as well as the periodic open-closed conformational change of the ATP-binding site, which are critical for the catalytic activity of GSK3β, are negligibly influenced in the mutated system compared with the wild-type (WT) system. This indicates that FRATide does not inhibit the GSK3β activity toward primed substrates. Additionally, MM_GBSA calculation indicates that the less energy-favorable GSK3β-FRATide complex is observed in the mutant than in the WT complex.