Associate Professor Ram Rajasekharan

Associate Professor

Metabolic engineering to increase quantity of oil in plants

Metabolic engineering to produce diacylglycerol, an anti-obesity oil, in plants

Our laboratory has been focusing on biosynthesis of triacylglycerols (fats and oils). Seeds that store triacylglycerols (TAG) are the commercial source of plant oils for food and industrial uses. Despite their economic importance, the biosynthesis of TAG has not been fully understood.

We have discovered new soluble TAG biosynthetic machinery in oilseeds that involves monoacylglycerol as an intermediate in the pathway. Monoacylglycerol is sequentially acylated by their respective acyltransferases to form TAG.  The novel genes involved in the pathway have been cloned and overexpressed. These genes are considered as the potential targets for genetic manipulation for providing improved quality / quantity oils. Similar cytosolic TAG biosynthetic machinery also exists as a complex in yeast.

Ghosh AK , Ramakrishnan G, Rajasekharan R (2008) YLR099C (ICT1) Encodes for a soluble acyl-CoA dependent lysophosphatidic acid acyltransferase responsible for enhanced phospholipid synthesis upon organic solvent stress in Saccharomyces cerevisiae. J Biol Chem PMID): 18252723

Reddy VS, Singh AK, RajasekharanR(2008) The Saccharomyces cerevisiae PHM8 gene encodes a soluble magnesium dependent lysophosphatidic acid phosphatase. J Biol Chem ( PMID): 18234677

Reddy MM, Rajasekharan R (2007) Serine/threonine/tyrosine protein kinase from Arabidopsis thaliana is dependent on serine residues for its activity. Arch Biochem Biophys 460: 122-128

Saha S, Enugutti B, Rajakumari S, Rajasekharan R (2006) Cytosolic triacylglycerol biosynthetic pthway in plants:Molecular cloning and expression of peanut cytosolic diacylglycerol acyltransferase. Plant Physiol 141: 1533-1543

Rudrabhatla P, Reddy MM, Rajasekharan R (2006) Genome-wide analysis and experimentation of plant serine/threonine/tyrosine-specific protein kinases. Plant Mol Biol 60: 295-320

Rudrabhatla P, RajasekharanR (2004)Functional characterization of peanut serine/threonine/tyrosine protein kinase: molecular docking and inhibition kinetics with tyrosine kinase inhibitors. Biochemistry 43: 12123-12132

Raychaudhuri S, Rajasekharan R (2003) Non-organellar acyl carrier protein from oleaginous yeast is a homologue of ribosomal protein P2. J Biol Chem 278: 37648-37657

Daniel J, Rajasekharan R (2003) Organogelation of plant oils and hydrocarbons by long-chain saturated fatty acids, fatty alcohols, wax esters, and dicarboxylic acids. J Am Oil Chem Soc 80: 417-421

Raychaudhuri S, Reddy MM, Rajkumar NR, Rajasekharan R (2003) Cytosolic iron superoxide dismutase is a part of triacylglycerol biosynthetic complex in oleaginous yeast. Biochem J 372: 587-594

Rudrabhatla P, Rajasekharan R (2003) Mutational analysis of stress responsive peanut dual specificity protein kinase: Identification of tyrosine residues involved in regulation of protein kinase activity. J Biol Chem 278: 17328-17335

Rudrabhatla P, Rajasekharan R (2002) Developmentally regulated dual-specificity kinase from peanut that is induced by abiotic stresses. Plant Physiol 130: 380-390

Gangar A, Raychaudhuri S, Rajasekharan R (2002) Alteration in the cytosolic triacylglycerol biosynthetic machinery leads to decreased cell growth and triacylglycerol synthesis in oleaginous yeast. Biochem J 365: 577-589

Shekar S, Tumaney AW, Rao TJVS, Rajasekharan R (2002) Isolation of lysophosphatidic acid phosphatase from developing peanut cotyledons. Plant Physiol 128: 988-996

Bhardwaj K, Raju A, Rajasekharan R (2001) Identification, Purification and Characterization of a Thermally Stable Lipase from Rice Bran: New Member of the (Phospho)lipase Family. Plant Physiol 127: 1728-1738

Gangar A, Karande AA, Rajasekharan R (2001) Purification and characterization of acyl-acyl carrier protein synthetase from oleaginous yeast and its role in triacylglycerol biosynthesis. Biochem J 360: 471-479

Gangar A, Karande AA, Rajasekharan R (2001) Isolation and localization of a cytosolic 10S triacylglycerol biosynthetic multienzyme complex from oleaginous yeast. J Biol Chem 276: 10290-10298

1. Rajasekharan R, Rodrigues R, Reddy S (2001) A novel herbicide comprising phytotoxins of Lasiodiplodia theobromae (LT) fungus, A process of producing the herbicide and a method of using the same - US Patent 6277786.
2. Rajasekharan R, Daniel J (2002) A process for preparing a novel synergistic solid/semi-solid organic composition - US Patent 6391928.
3. Rajasekharan R, Bhardwaj K (2002) Process of isolation and utilization of rice bran lipase - PCT International Publication No. WO 02/101033.
4. Rajasekharan R, Daniel J (2003) Novel synergistic solid/semi-solid organic composition, a process of preparing such organic composition and a method of altering physical properties of liquid neutral organic compounds and their mixtures. US Patent Application 20030176540 ; September 18, 2003, Pending.
5. Rajasekharan R (2007) A novel triacylglycerol biosynthesis in the cytosol of eukaryotes - US Patent 7229815.
6. RajasekharanR, Daniel J (2007) A novel reversible solid/semi-solid composition and a process for preparing the same. Indian Patent 208610.

• Isolation of lipase from oil palm mesocarp
• Physiological role of serine/threonine/tyrosine protein kinase in plants

• Molecular cloning of lipase from oil palm
• Elucidate the biochemical function of CGI-58, the causative gene for Chanarin-Dorfman syndrome
• Interaction of CGI-58 with adipocytes triglyceride lipase

Monoacylglycerol as an intermediate in triacylglycerol biosynthesis in oilseeds. 17 th International Plant Lipid Conference, Michigan State University, East Lansing, USA, June 2006.

Introduction of cytosolic diacylglycerol acyltransferase from oleaginous yeast leads to accumulation of triacylglycerol in no-oil producing organisms. Yeast 2005, International Conference on the Biology of Yeasts, Indian Institute of Science, Bangalore, India, Sept. 2005.

Triacylglycerol biosynthesis in eukaryotes - AgBiotech, DuPont Experimental Station , Wilmington, Delaware 19880-0402, Feb. 2005.

Monoacylglycerol as an intermediate in triacylglycerol biosynthesis in oilseeds: Cloning and expression of soluble diacylglycerol acyltransferase – 1 st European symposium on plant lipids, RWTH Aachen, Germany, Sept. 2003.

Oil gelation with fatty acids and their derivatives, SymBioSys Genetics Inc., Calgary, Canada, Sept. 2003.

Alternative pathway for triacylglycerol biosynthesis in plants – University of Lethbridge, Canada, Sept. 2003.

Triacylglycerol biosynthesis in eukaryotes – Plant Biotechnology Institute, Saskatoon, National Research Council, Canada, Aug. 2003.

Consume fat to combat obesity – AgWest Inc, Saskatoon, Canada, Aug. 2003.

• sciencenow.sciencemag.org/cgi/content/full/2003/305/4
• www.agwest.sk.ca/publications/agbiotech/abboct03.rtf
• www.hindu.com/2004/10/29/stories/2004102917100500.htm
• www.oliveoilsource.com/newsletter/olivenews6-7.htm
• www.checkbiotech.org/green_News_Genetics.aspx?infoId=16313
• in.biz.yahoo.com/071201/259/6ny10.htm