Dual regulation of diacylglycerol kinase (DGK)-θ: Polybasic proteins promote activation by phospholipids and increase substrate affinity

Becky Tu-Sekine, Daniel M. Raben

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)41619-41627
Number of pages9
JournalJournal of Biological Chemistry
Volume287
Issue number50
DOIs
StatePublished - Dec 7 2012

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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