Dataset Information

Toggling of Diacylglycerol Affinity Correlates with Conformational Plasticity in C1 Domains.

ABSTRACT: Conserved homology-1 (C1) domains are peripheral membrane domains that target their host proteins to diacylglycerol (DAG)-containing membranes. It has been previously shown that a conservative aromatic mutation of a single residue in the C1 domain has a profound effect on DAG affinity. We report that the "DAG-toggling" mutation changes the conformational dynamics of the loop region that forms the binding site for the C1 activators. Moreover, there is a correlation among the residue identity at the mutation site, DAG affinity, and loop dynamics in four C1 variants. We propose that "toggling" of DAG affinity may occur through modulation of both protein-membrane interactions and the geometry of the activator-binding cleft, with the loop dynamics being responsible for the latter.

SUBMITTER: Stewart MD

PROVIDER: S-EPMC5600822 | biostudies-literature | 2017 May

REPOSITORIES: biostudies-literature

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Toggling of Diacylglycerol Affinity Correlates with Conformational Plasticity in C1 Domains.

Stewart Mikaela D MD Igumenova Tatyana I TI

Biochemistry 20170518 21

Conserved homology-1 (C1) domains are peripheral membrane domains that target their host proteins to diacylglycerol (DAG)-containing membranes. It has been previously shown that a conservative aromatic mutation of a single residue in the C1 domain has a profound effect on DAG affinity. We report that the "DAG-toggling" mutation changes the conformational dynamics of the loop region that forms the binding site for the C1 activators. Moreover, there is a correlation among the residue identity at t ...[more]

PMID: 28505428

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Project description:Diacylglycerol kinases (DGKs) are multi-domain lipid kinases that phosphorylate diacylglycerol into phosphatidic acid, modulating the levels of these key signaling lipids. Recently, increasing attention has been paid to DGKα isozyme as a potential target for cancer immunotherapy. We have previously shown that DGKα is positively regulated by Ca2+ binding to its N-terminal EF-hand domains (DGKα-EF). However, little progress has been made for the structural biology of mammalian DGKs and the molecular mechanism underlying the Ca2+ -triggered activation remains unclear. Here we report the first crystal structure of Ca2+ -bound DGKα-EF and analyze the structural changes upon binding to Ca2+ . DGKα-EF adopts a canonical EF-hand fold, but unexpectedly, has an additional α-helix (often called a ligand mimic [LM] helix), which is packed into the hydrophobic core. Biophysical and biochemical analyses reveal that DGKα-EF adopts a protease-susceptible "open" conformation without Ca2+ that tends to form a dimer. Cooperative binding of two Ca2+ ions dissociates the dimer into a well-folded monomer, which resists to proteolysis. Taken together, our results provide experimental evidence that Ca2+ binding induces substantial conformational changes in DGKα-EF, which likely regulates intra-molecular interactions responsible for the activation of DGKα and suggest a possible role of the LM helix for the Ca2+ -induced conformational changes. SIGNIFICANCE STATEMENT: Diacylglycerol kinases (DGKs), which modulates the levels of two lipid second messengers, diacylglycerol and phosphatidic acid, is still structurally enigmatic enzymes since its first identification in 1959. We here present the first crystal structure of EF-hand domains of diacylglycerol kinase α in its Ca2+ bound form and characterize Ca2+ -induced conformational changes, which likely regulates intra-molecular interactions. Our study paves the way for future studies to understand the structural basis of DGK isozymes.

Dataset Information

Toggling of Diacylglycerol Affinity Correlates with Conformational Plasticity in C1 Domains.

Publications

Toggling of Diacylglycerol Affinity Correlates with Conformational Plasticity in C1 Domains.

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