Abstract
Understanding the influence of ubiquitously present plant steroids on mammalian cell biology is currently of interest. Feedback inhibition of HMGCoA reductase (HMGCR) catalytic activity in the transformation of HMG-CoA to mevalonate is a significant regulatory step in sterol biosynthetic pathway. To assess the role of dietary steroids in this biochemical transformation, the phytosteroid isoform 28-homobrassinolide (28-HB), 90 % pure, obtained from Godrej Agrovet (India) was used to determine its effect on mammalian HMG-CoA reductase. Photometric assay of pure human and select rat tissue HMGCR post 28-HB oral feed, PCR-HMGCR gene expression, and in silico docking of 28-HB and HMGCoA on HMGCR protein template were carried out. Using an oral feed regimen of pure 28-HB, we noted a decrease of 16 % in liver, 17.1 % in kidney and 9.3 % in testicular HMGCR enzyme activity, 25 % in HMGCR gene expression and 44 % in the activity of pure human HMGCR due to this plant oxysterol. In silico docking studies yielded binding metrics for 28-HB-HMGCR lower than for HMGCoA-HMGCR, indicating stronger binding of HMGCR by this ligand. 28-HB exerts differential effects on rat tissue HMGCR, down regulates liver HMGCR gene expression and significantly inhibits HMGCR activity.
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Acknowledgments
The authors sincerely acknowledge the financial support received from Dept. of Biotechnology, Govt. of India under DBT-IPLS programme (Sanction Order No.: BT/PR14554/INF/22/125/2010 dated: 28.09.2010), University Grants Commission, New Delhi, Department of Science and Technology, Government of India, UGC-SAP, and DST-FIST programs. Research carried out at the Centre for Bioinformatics, Pondicherry University, Puducherry, India, is funded by the Department of Information Technology (DIT) and the Department of Biotechnology (DBT), Government of India, New Delhi, India. The authors gratefully acknowledge Dr. Asmita Dasgupta and Mr. N. Jayachandra Reddy, Pondicherry University, Puducherry, for providing valuable suggestions.
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Mukherjee, V., Vijayalaksmi, D., Gulipalli, J. et al. A plant oxysterol, 28-homobrassinolide binds HMGCoA reductase catalytic cleft: stereoselective avidity affects enzyme function. Mol Biol Rep 43, 1049–1058 (2016). https://doi.org/10.1007/s11033-016-4052-5
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DOI: https://doi.org/10.1007/s11033-016-4052-5