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BioMed Research International
Volume 2014, Article ID 934351, 14 pages
http://dx.doi.org/10.1155/2014/934351
Research Article

Molecular Cloning and Biochemical Characterization of a Recombinant Sterol 3-O-Glucosyltransferase from Gymnema sylvestre R.Br. Catalyzing Biosynthesis of Steryl Glucosides

1Metabolic and Structural Biology Department, CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), P.O. CIMAP, Lucknow, Uttar Pradesh 226015, India
2Centre of Innovative and Applied Bioprocessing, (A National Institute under Department of Biotechnology Gov. of India) C-127, Phase-8, Industrial Area, S.A.S. Nagar, Mohali, Punjab 160071, India
3Department of Biotechnology, Uttar Pradesh Technical University, Lucknow, Uttar Pradesh 226021, India

Received 26 February 2014; Revised 9 June 2014; Accepted 23 June 2014; Published 27 August 2014

Academic Editor: Dinesh A. Nagegowda

Copyright © 2014 Pragya Tiwari et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Gymnema sylvestre R.Br., a pharmacologically important herb vernacularly called Gur-Mar (sugar eliminator), is widely known for its antidiabetic action. This property of the herb has been attributed to the presence of bioactive triterpene glycosides. Although some information regarding pharmacology and phytochemical profiles of the plant are available, no attempts have been made so far to decipher the biosynthetic pathway and key enzymes involved in biosynthesis of steryl glucosides. The present report deals with the identification and catalytic characterization of a glucosyltransferase, catalyzing biosynthesis of steryl glycosides. The full length cDNA (2572 bp) contained an open reading frame of 2106 nucleotides that encoded a 701 amino acid protein, falling into GT-B subfamily of glycosyltransferases. The GsSGT was expressed in Escherichia coli and biochemical characterization of the recombinant enzyme suggested its key role in the biosynthesis of steryl glucosides with catalytic preference for C-3 hydroxyl group of sterols. To our knowledge, this pertains to be the first report on cloning and biochemical characterization of a sterol metabolism gene from G. sylvestre R.Br. catalyzing glucosylation of a variety of sterols of biological origin from diverse organisms such as bacteria, fungi, and plants.