Expression, purification, and crystallization of human CK2α in complex with the natural flavonoid quercetin

Expression, purification, and crystallization of human CK2α in complex with the natural flavonoid quercetin

Over 300 polypeptide substrates can undergo catalysis by the constitutively active Ser/Thr kinase, human casein kinase 2 alpha (hCK2α). Quercetin, a naturally occurring polyphenolic compound, is well-known for inhibiting hCK2α, thereby regulating cellular signaling pathways. In this study, we crystallized the hCK2α-quercetin complex to elucidate the inhibitory mechanism of quercetin on hCK2α through the complex structure. The hanging drop vapor diffusion method was employed for crystallizing the hCK2α-quercetin complex, and the resulting crystal diffracted to a resolution of 2.11 Å. X-ray diffraction data analysis revealed that the crystal of the hCK2α-quercetin complex belonged to the P43212 space group, with unit cell dimensions of a = b = 127.604 Å, c = 124.314 Å, and α = β = γ = 90.00°. In an initial density map, quercetin was bound well into hCK2α.