Location: Plant Physiology and Genetics ResearchTitle: Plant acyl-CoA:lysophosphatidylcholine acyltransferases (LPCATs) have different specificities in their forward and reverse reactions Author
|Yilmaz, Jenny Lindberg|
Submitted to: Journal of Biological Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/30/2013
Publication Date: 11/4/2013
Citation: Lager, I., Yilmaz, J., Zhou, X., Jasieniecka, K., Kazachkov, M., Wang, P., Zou, J., Weselake, R., Smith, M.A., Bayon, S., Dyer, J.M., Shockey, J.M., Heinz, E., Green, A., Banas, A., Stymne, S. 2013. Plant acyl-CoA:lysophosphatidylcholine acyltransferases (LPCATs) have different specificities in their forward and reverse reactions. Journal of Biological Chemistry. 288(52):36902-36914. Interpretive Summary: Plants are autotrophic organisms that convert sunlight and carbon dioxide into the chemicals needed to support life. One of the main types of compounds produced in plants are called fatty acids, and these make up the majority of “vegetable oils” that are used for human nutrition and culinary purposes. Despite the importance of fatty acids to both the cellular activity in plants, and nutrition in humans, little is known about the enzymatic “machinery” in plant cells that is involved in transferring fatty acids from their site of synthesis in chloroplasts to other locations in the cell, where they may be converted into new types of lipids including the seed oils we call “vegetable oil”. In this manuscript, a consortium of scientists, including a scientist at the ARS lab in Maricopa, provide detailed insight to a key class of enzymes in plants that is involved in transferring fatty acids between different types of lipids in plant cells. This information fills a significant gap in our knowledge of plant lipid production, and will stimulate new research on the role of these enzymes in producing different types of lipids including vegetable oils, biofuels, and plant oils that can be used for industrial purposes.
Technical Abstract: Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT) enzymes have central roles inacyl editing of phosphatidylcholine (PC). Plant LPCAT genes were expressed in yeast and characterized biochemically in microsomal preparations of the cells. Specificities for different acyl-CoAs were similar for seven LPCATs from five different species, with a preference for C18 unsaturated acyl-CoA and low activity with palmitoleoyl-CoA and ricinoleoyl (12-hydroxy-octadec-9-enoyl)-CoA. We showed that Arabidopsis LPCAT1 and LPCAT2 enzymes catalysed the acylation and de-acylation of both sn-positions of PC and with a preference for the sn-2 position. When acyl specificities of the Arabidopsis LPCATs were measured in the reverse reaction, sn-2 bound C18 unsaturated acyl groups from PC were transferred to acyl-CoA to the same extent. However, a ricinoleoyl group at the sn-2-position of PC was removed over 4-6 fold faster than an oleoyl group in the reverse reaction, despite poor utilization in the forward reaction. The data presented, taken together with earlier published reports on in vivo lipid metabolism, support the hypothesis that plant LPCAT enzymes play an important role in regulating the acyl-CoA composition in plant cells by transferring polyunsaturated and hydroxy fatty acids produced on PC directly to the acyl-CoApool for further metabolism or catabolism.