Diacylglycerol Kinase ϵ Is Selective for Both Acyl Chains of Phosphatidic Acid or Diacylglycerol Export

@article{citeulike:6044025, abstract = {10.1074/jbc.M109.050617 The phosphatidylinositol (PI) cycle mediates many cellular events by controlling the metabolism of many lipid second messengers. Diacylglycerol kinase \"{I}µ (DGK\"{I}µ) has an important role in this cycle. DGK\"{I}µ is the only DGK isoform to show inhibition by its product phosphatidic acid (PA) as well as substrate specificity for -2 arachidonoyl-diacylglycerol (DAG). Here, we show that this inhibition and substrate specificity are both determined by selectivity for a combination of the -1 and -2 acyl chains of PA or DAG, respectively, preferring the most prevalent acyl chain composition of lipids involved specifically in the PI cycle, 1-stearoyl-2-arachidonoyl. Although the difference in rate for closely related lipid species is small, there is a significant enrichment of 1-stearoyl-2-arachidonoyl PI because of the cyclical nature of PI turnover. We also show that the inhibition of DGK\"{I}µ by PA is competitive and that the deletion of the hydrophobic segment and cationic cluster of DGK\"{I}µ does not affect its selectivity for the acyl chains of PA or DAG. Thus, this active site not only recognizes the lipid headgroup but also a combination of the two acyl chains in PA or DAG. We propose a mechanism of DGK\"{I}µ regulation where its dual acyl chain selectivity is used to negatively regulate its enzymatic activity in a manner that ensures DGK\"{I}µ remains committed to the PI turnover cycle. This novel mechanism of enzyme regulation within a signaling pathway could serve as a template for the regulation of enzymes in other pathways in the cell.}, author = {Lung, Michael and Shulga, Yulia V. and Ivanova, Pavlina T. and Myers, David S. and Milne, Stephen B. and Brown, H. Alex and Topham, Matthew K. and Epand, Richard M.}, citeulike-article-id = {6044025}, citeulike-linkout-0 = {http://dx.doi.org/10.1074/jbc.M109.050617}, citeulike-linkout-1 = {http://www.jbc.org/content/284/45/31062.abstract}, citeulike-linkout-2 = {http://www.jbc.org/content/284/45/31062.full.pdf}, citeulike-linkout-3 = {http://view.ncbi.nlm.nih.gov/pubmed/19744926}, citeulike-linkout-4 = {http://www.hubmed.org/display.cgi?uids=19744926}, day = {6}, doi = {10.1074/jbc.M109.050617}, journal = {Journal of Biological Chemistry}, keywords = {acid, fatty, lipase, lung09pdf, regulation, specificity}, month = {November}, number = {45}, pages = {31062--31073}, posted-at = {2009-10-30 19:18:29}, priority = {2}, title = {Diacylglycerol Kinase \"{I}µ Is Selective for Both Acyl Chains of Phosphatidic Acid or Diacylglycerol}, url = {http://dx.doi.org/10.1074/jbc.M109.050617}, volume = {284}, year = {2009} }

TY - JOUR ID - citeulike:6044025 L3 - citeulike-article-id:6044025 N2 - 10.1074/jbc.M109.050617 The phosphatidylinositol (PI) cycle mediates many cellular events by controlling the metabolism of many lipid second messengers. Diacylglycerol kinase ϵ (DGKϵ) has an important role in this cycle. DGKϵ is the only DGK isoform to show inhibition by its product phosphatidic acid (PA) as well as substrate specificity for -2 arachidonoyl-diacylglycerol (DAG). Here, we show that this inhibition and substrate specificity are both determined by selectivity for a combination of the -1 and -2 acyl chains of PA or DAG, respectively, preferring the most prevalent acyl chain composition of lipids involved specifically in the PI cycle, 1-stearoyl-2-arachidonoyl. Although the difference in rate for closely related lipid species is small, there is a significant enrichment of 1-stearoyl-2-arachidonoyl PI because of the cyclical nature of PI turnover. We also show that the inhibition of DGKϵ by PA is competitive and that the deletion of the hydrophobic segment and cationic cluster of DGKϵ does not affect its selectivity for the acyl chains of PA or DAG. Thus, this active site not only recognizes the lipid headgroup but also a combination of the two acyl chains in PA or DAG. We propose a mechanism of DGKϵ regulation where its dual acyl chain selectivity is used to negatively regulate its enzymatic activity in a manner that ensures DGKϵ remains committed to the PI turnover cycle. This novel mechanism of enzyme regulation within a signaling pathway could serve as a template for the regulation of enzymes in other pathways in the cell. IS - 45 JF - Journal of Biological Chemistry EP - 31073 TI - Diacylglycerol Kinase ϵ Is Selective for Both Acyl Chains of Phosphatidic Acid or Diacylglycerol VL - 284 SP - 31062 KW - acid KW - fatty KW - lipase KW - lung09pdf KW - regulation KW - specificity AU - Lung, Michael AU - Shulga, Yulia AU - Ivanova, Pavlina AU - Myers, David AU - Milne, Stephen AU - Brown, Alex AU - Topham, Matthew AU - Epand, Richard PY - 2009/11/06/ UR - http://dx.doi.org/10.1074/jbc.M109.050617 ER -