Curcumin specifically binds to the human calcium–calmodulin-dependent protein kinase IV: fluorescence and molecular dynamics simulation studies

Abstract

Calcium–calmodulin-dependent protein kinase IV (CAMK4) plays significant role in the regulation of calcium-dependent gene expression, and thus, it is involved in varieties of cellular functions such as cell signaling and neuronal survival. On the other hand, curcumin, a naturally occurring yellow bioactive component of turmeric possesses wide spectrum of biological actions, and it is widely used to treat atherosclerosis, diabetes, cancer, and inflammation. It also acts as an antioxidant. Here, we studied the interaction of curcumin with human CAMK4 at pH 7.4 using molecular docking, molecular dynamics (MD) simulations, fluorescence binding, and surface plasmon resonance (SPR) methods. We performed MD simulations for both neutral and anionic forms of CAMK4-curcumin complexes for a reasonably long time (150 ns) to see the overall stability of the protein–ligand complex. Molecular docking studies revealed that the curcumin binds in the large hydrophobic cavity of kinase domain of CAMK4 through several hydrophobic and hydrogen-bonded interactions. Additionally, MD simulations studies contributed in understanding the stability of protein–ligand complex system in aqueous solution and conformational changes in the CAMK4 upon binding of curcumin. A significant increase in the fluorescence intensity at 495 nm was observed (λ_exc = 425 nm), suggesting a strong interaction of curcumin to the CAMK4. A high binding affinity (K_D = 3.7 × 10⁻⁸ ± .03 M) of curcumin for the CAMK4 was measured by SPR further indicating curcumin as a potential ligand for the CAMK4. This study will provide insights into designing a new inspired curcumin derivatives as therapeutic agents against many life-threatening diseases.

Keywords:

• curcumin
• calcium–calmodulin-dependent protein kinase IV
• molecular dynamics simulation
• docking
• drug target
• high affinity ligand

Acknowledgments

We sincerely thank Dana-Farber/Harvard Cancer Center (DF/HCC) Boston, MA 02215, for providing the clone of CAMK4. HN thanks ICMR (Government of India) for the award of Senior Research Fellowship.

Disclosure statement

Authors declare no conflict of interest regarding any financial and personal relationships with other people or organizations that could inappropriately influence (bias) this work.

Additional information

Funding

This work was financial supported by the Department of Science and Technology (Government of India); Indian Council for Medical Research (ICMR).