TY - JOUR
T1 - Dual regulation of diacylglycerol kinase (DGK)-θ
T2 - Polybasic proteins promote activation by phospholipids and increase substrate affinity
AU - Tu-Sekine, Becky
AU - Raben, Daniel M.
PY - 2012/12/7
Y1 - 2012/12/7
N2 - Diacylglycerol kinases are important mediators of lipid signaling cascades, and insight into their regulation is of increasing interest. Using purified DGK-θ, we show that this isoform is subject to dual regulation and that the previously characterized stimulation by acidic phospholipids is dependent on the presence of a positively charged protein or peptide. Polybasic cofactors lowered the Km for diacylglycerol at the membrane surface (K m(surf)), and worked synergistically with acidic phospholipids to increase activity 10- to 30-fold, suggesting that the purified enzyme is autoinhibited. Vesicle pulldown studies showed that acidic phospholipids recruit polybasic cofactors to the vesicle surface but have little effect on the membrane association of DGK-θ, suggesting that a triad of enzyme, acidic lipid and basic protein are necessary for interfacial activity. Importantly, these data demonstrate that the interfacial association and catalytic activity of DGK-θ are independently regulated. Finally, we show that DGK-θ directly interacts with, and is activated by, basic proteins such as histone H1 and Tau with nM affinity, consistent with a potential role for a polybasic protein or protein domain in the activation of this enzyme.
AB - Diacylglycerol kinases are important mediators of lipid signaling cascades, and insight into their regulation is of increasing interest. Using purified DGK-θ, we show that this isoform is subject to dual regulation and that the previously characterized stimulation by acidic phospholipids is dependent on the presence of a positively charged protein or peptide. Polybasic cofactors lowered the Km for diacylglycerol at the membrane surface (K m(surf)), and worked synergistically with acidic phospholipids to increase activity 10- to 30-fold, suggesting that the purified enzyme is autoinhibited. Vesicle pulldown studies showed that acidic phospholipids recruit polybasic cofactors to the vesicle surface but have little effect on the membrane association of DGK-θ, suggesting that a triad of enzyme, acidic lipid and basic protein are necessary for interfacial activity. Importantly, these data demonstrate that the interfacial association and catalytic activity of DGK-θ are independently regulated. Finally, we show that DGK-θ directly interacts with, and is activated by, basic proteins such as histone H1 and Tau with nM affinity, consistent with a potential role for a polybasic protein or protein domain in the activation of this enzyme.
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U2 - 10.1074/jbc.M112.404855
DO - 10.1074/jbc.M112.404855
M3 - Article
C2 - 23091060
AN - SCOPUS:84871289332
SN - 0021-9258
VL - 287
SP - 41619
EP - 41627
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 50
ER -