Biophysical and in-silico studies on the structure-function relationship of Brugia malayi protein disulfide isomerase

Abstract

Human Lymphatic filariasis is caused by parasitic nematodes Wuchereria bancrofti, Brugia malayi, and Brugia timori. Protein disulfide isomerase (PDI), a redox-active enzyme, helps to form and isomerize the disulfide bonds, thereby acting as a chaperone. Such activity is essential for activating many essential enzymes and functional proteins. Brugia malayi protein disulfide isomerase (BmPDI) is crucial for parasite survival and an important drug target. Here, we used a combination of spectroscopic and computational analysis to study the structural and functional changes in the BmPDI during unfolding. Tryptophan fluorescence data revealed two well-separated transitions during the unfolding process, suggesting that the unfolding of the BmPDI is non-cooperative. The binding of the fluorescence probe 8-anilino-1-naphthalene sulfonic acid dye (ANS) validated the results obtained by the pH unfolding. The dynamics of molecular simulation performed at different pH conditions revealed the structural basis of BmPDI unfolding. Detailed analysis suggested that under different pH, both the global structure and the conformational dynamics of the active site residues were differentially altered. Our multiparametric study reveals the differential dynamics and collective motions of BmPDI unfolding, providing insights into its structure-function relationship.

Communicated by Ramaswamy H. Sarma

Keywords:

• Brugia malayi protein disulfide isomerase
• pH
• urea and guanidine hydrochloride
• protein-unfolding
• molecular dynamics

Acknowledgements

Pawan Kumar Doharey is thankful to UGC-New Delhi for supporting him in the form of a Dr. D.S. Kothari Post-Doctoral Fellowship. Pravesh Verma is thankful to CSIR-Central Drug Research Institute and UGC-New Delhi for providing him with the funding and lab facilities. SKS is grateful to the Institute of Eminence, Banaras Hindu University, Varanasi, India, for providing the Malaviya Postdoctoral Fellowship to carry out the current research work. The authors extend their appreciation to Researchers Supporting project number (RSP2023R237), King Saud University, Riyadh, Saudi Arabia.

Author contributions

P.K.D., P.V., and B.S. conceived and designed the experiments. P.K.D., P.V., and S.K.S. performed the experiments (wet lab). A.D. and M.K. performed the in-silico experiments. P.K.D., P.V., S.K.S., A.D., T.T., and B.S. analyzed the data. P.K.D., P.V., A.D., and S.K.S. contributed reagents/materials/analysis tools. P.K.D., P.V., A.D., S.K.S., and T.T. wrote the paper. M.K. M.A. and N.J.S. critically reviewed the manuscript and analyzed the data.

Data availability statement

The data will be provided on reasonable request.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was funded by the Researchers Supporting project number (RSP2023R237), King Saud University, Riyadh, Saudi Arabia.