Prokaryotic expression of human-sourced and zebrafish-sourced protein kinase A alpha catalytic subunits combined with in vitro and in silico assay.

The extensively studied cAMP-dependent protein kinase A (PKA) is involved in the regulation of critical cell processes, including metabolism, gene expression, and cell proliferation. Therefore, PKA has been viewed increasingly as potential target for variety of drugs and environmental endocrine disruptors. Consequentially, the preparation of PKA protein became an important initial step for the subsequent exploration of PKA's character in endocrine disrupting effects of pesticides. To investigate PKA protein, which is potential to be the environmental endocrine toxicity target of triazole fungicides, a strategy to heterologously express protein kinase A catalytic alpha subunit of human (hPKAcα) and zebrafish (zPKAcα) in Escherichia coli (E. coli) BL21(DE3) host cells was demonstrated. After optimizing conditions and protein purification, we successfully obtained enzymatically active hPKAcα and zPKAcα. Western blot analysis indicated that the recombinant hPKAcα and zPKAcα still retained their characteristic antigenicity and binding activity, while in vitro kinase activity assays revealed that the recombinant hPKAcα and zPKAcα maintained enzyme activity. By in silico methods including homology modelling and molecular docking, the affinity of ligands and the models of hPKAcα and zPKAcα were further tested. The present study offered a valuable method to achieve the prokaryotic expression of a eukaryotic protein kinase and laid a foundation to facilitate further investigation of toxicological target of triazole pesticides.