Lokesh Kumar Narnoliya1, Neelam Sangwan2,3, Jyoti Singh Jadaun1,4, Shilpi Bansal1, Rajender Singh Sangwan5,6. 1. Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), Lucknow, 226015, India. 2. Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), Lucknow, 226015, India. drneelamsangwan@gmail.com. 3. Department of Biochemistry, Central University of Haryana, Mahendergarh, 123031, Haryana, India. drneelamsangwan@gmail.com. 4. Department of Botany, Dayanand Girls Postgraduate College, Kanpur, 208001, India. 5. Department of Metabolic and Structural Biology, CSIR-Central Institute of Medicinal and Aromatic Plants (CSIR-CIMAP), Lucknow, 226015, India. dr.sangwan@gmail.com. 6. Academy of Scientific and Innovative Research (AcSIR), CSIR-HRDC Campus, Kamla Nehru Nagar, Sector-19, Ghaziabad, 201002, Uttar Pradesh, India. dr.sangwan@gmail.com.
Abstract
MAIN CONCLUSION: The recombinant caffeic acid 3-O-methyltransferase gene has been cloned and characterized from Neem. The gene is involved in ferulic acid biosynthesis, a key intermediate component of lignin biosynthesis. Azadirachta indica (Neem) is a highly reputed traditional medicinal plant and is phytochemically well-known for its limonoids. Besides limonoids, phenolics are also distinctively present, which add more medicinal attributes to Neem. Caffeic acid is one of such phenolic compound and it can be converted enzymatically into another bioactive phytomolecule, ferulic acid. This conversion requires transfer of a methyl group from a donor to caffeic acid under the catalytic action of an appropriate methyltransferase. In this study, caffeic acid 3-O-methyltransferase gene from Neem (NCOMT) fruits has been isolated and heterologously expressed in E. coli. The recombinant NCOMT enzyme was purified, which exhibited efficient catalytic conversion of caffeic acid into ferulic acid, a highly potential pharmaceutical compound. The purified recombinant enzyme was physico-kinetically characterized for its catalysis. The analysis of tissue-wide expression of NCOMT gene revealed interesting pattern of transcript abundance reflecting its role in the development of fruit tissues. Further, NCOMT was heterologously overexpressed in Withania somnifera and Ocimum species, to analyze its role in ferulic acid biosynthesis in planta. Thus, the study provides insight for the endogenous role of NCOMT in ferulic acid biosynthesis en route to lignin, an important structural component. To the best of our knowledge, NCOMT pertains to be the first enzyme of the secondary metabolism that has been purified and kinetically characterized from Neem. This study may also have important prospects of applications as the observation on heterologous expression of NCOMT showed its involvement in the maintenance of the in vivo pool of ferulic acid in the plants. Thus, the study involving NCOMT opens up new dimensions of metabolic engineering approaches for the biosynthesis of potential therapeutically important phytomolecules in heterologous systems.
MAIN CONCLUSION: The recombinant caffeic acid 3-O-methyltransferase gene has been cloned and characterized from Neem. The gene is involved in ferulic acid biosynthesis, a key intermediate component of lignin biosynthesis. Azadirachta indica (Neem) is a highly reputed traditional medicinal plant and is phytochemically well-known for its limonoids. Besides limonoids, phenolics are also distinctively present, which add more medicinal attributes to Neem. Caffeic acid is one of such phenolic compound and it can be converted enzymatically into another bioactive phytomolecule, ferulic acid. This conversion requires transfer of a methyl group from a donor to caffeic acid under the catalytic action of an appropriate methyltransferase. In this study, caffeic acid 3-O-methyltransferase gene from Neem (NCOMT) fruits has been isolated and heterologously expressed in E. coli. The recombinant NCOMT enzyme was purified, which exhibited efficient catalytic conversion of caffeic acid into ferulic acid, a highly potential pharmaceutical compound. The purified recombinant enzyme was physico-kinetically characterized for its catalysis. The analysis of tissue-wide expression of NCOMT gene revealed interesting pattern of transcript abundance reflecting its role in the development of fruit tissues. Further, NCOMT was heterologously overexpressed in Withania somnifera and Ocimum species, to analyze its role in ferulic acid biosynthesis in planta. Thus, the study provides insight for the endogenous role of NCOMT in ferulic acid biosynthesis en route to lignin, an important structural component. To the best of our knowledge, NCOMT pertains to be the first enzyme of the secondary metabolism that has been purified and kinetically characterized from Neem. This study may also have important prospects of applications as the observation on heterologous expression of NCOMT showed its involvement in the maintenance of the in vivo pool of ferulic acid in the plants. Thus, the study involving NCOMT opens up new dimensions of metabolic engineering approaches for the biosynthesis of potential therapeutically important phytomolecules in heterologous systems.
Authors: David R Gang; Noa Lavid; Chloe Zubieta; Feng Chen; Till Beuerle; Efraim Lewinsohn; Joseph P Noel; Eran Pichersky Journal: Plant Cell Date: 2002-02 Impact factor: 11.277