title: Biophysical and molecular-dynamics studies of phosphatidic acid binding by the Dvl-2 DEP domain.
abstract: The Wnt-dependent, β-catenin-independent pathway modulates cell movement and behavior. A downstream regulator of this signaling pathway is Dishevelled (Dvl), which, among other multiple interactions, binds to the Frizzled receptor and the plasma membrane via phosphatidic acid (PA) in a mechanism proposed to be pH-dependent. While the Dvl DEP domain is central to the β-catenin-independent Wnt signaling function, the mechanism underlying its physical interaction with the membrane remains elusive. In this report, we elucidate the structural and functional basis of PA association to the Dvl2 DEP domain. Nuclear magnetic resonance, molecular-dynamics simulations, and mutagenesis data indicated that the domain interacted with the phospholipid through the basic helix 3 and a contiguous loop with moderate affinity. The association suggested that PA binding promoted local conformational changes in helix 2 and β-strand 4, both of which are compromised to maintain a stable hydrophobic core in the DEP domain. We also show that the Dvl2 DEP domain bound PA in a pH-dependent manner in a mechanism that resembles deprotonation of PA. Collectively, our results structurally define the PA-binding properties of the Dvl2 DEP domain, which can be exploited for the investigation of binding mechanisms of other DEP domain-interacting proteins.
authors.affiliation: Protein Signaling Domains Laboratory, Virginia Tech, Blacksburg, Virginia. Electronic address: capellut@vt.edu.
authors.forename: Daniel G S
authors.initials: DG
authors.lastname: Capelluto
authors.affiliation: Protein Signaling Domains Laboratory, Virginia Tech, Blacksburg, Virginia.
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Protein Signaling Domains Laboratory, Virginia Tech, Blacksburg, Virginia; Integrated Cellular Responses Laboratory, Department of Biological Sciences, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia.
authors.forename: Andrew
authors.initials: A
authors.lastname: Lucas
authors.affiliation: Department of Biochemistry, Virginia Tech, Blacksburg, Virginia.
authors.forename: Justin A
authors.initials: JA
authors.lastname: Lemkul
authors.affiliation: Protein Signaling Domains Laboratory, Virginia Tech, Blacksburg, Virginia.
authors.forename: Shuyan
authors.initials: S
authors.lastname: Xiao
authors.affiliation: Integrated Cellular Responses Laboratory, Department of Biological Sciences, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia.
authors.forename: Xiangping
authors.initials: X
authors.lastname: Fu
authors.affiliation: Protein Signaling Domains Laboratory, Virginia Tech, Blacksburg, Virginia.
authors.forename: Furong
authors.initials: F
authors.lastname: Sun
authors.affiliation: Department of Biochemistry, Virginia Tech, Blacksburg, Virginia.
authors.forename: David R
authors.initials: DR
authors.lastname: Bevan
authors.affiliation: Integrated Cellular Responses Laboratory, Department of Biological Sciences, Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia.
authors.forename: Carla V
authors.initials: CV
authors.lastname: Finkielstein
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism*; D055592:Biophysical Phenomena; D002462:Cell Membrane / Q000378:metabolism; D051157:Frizzled Receptors / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D056004:Molecular Dynamics Simulation; D010712:Phosphatidic Acids / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D015398:Signal Transduction
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051157:Frizzled Receptors; D010712:Phosphatidic Acids