DOC2B, C2 Domains, and Calcium: A Tale of Intricate Interactions

Friedrich, Reut; Yeheskel, Adva; Ashery, Uri

doi:10.1007/s12035-009-8094-8

Cited by 32 publications

(25 citation statements)

References 71 publications

(134 reference statements)

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“…The Ca 2+ ion contacts the acidic side chains of residues Asp413 of CBR1 and Asp476 and Glu482 of CBR3 but maintaining an incomplete coordination. Strikingly, this ion was located close to the conventional position of Ca2 described for most of the Ca 2+ -dependent C2 domains (2,5,32), indicating the existence of an intermediate step in the calcium-binding process. Thus, we compared both the 3D structures and electrostatic potentials of the Ca 2+ -free (Protein Data Bank, PDB ID code 2CHD) (29) and the 2Ca 2+ -bound structures (PDB ID code 2K3H) (27) with the structure determined in this work.…”

Section: Resultsmentioning

confidence: 76%

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Guillén

Ferrer-Orta

Buxaderas

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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Proteins containing C2 domains are the sensors for Ca 2+ and PI (4,5)P 2 in a myriad of secretory pathways. Here, the use of a freemounting system has enabled us to capture an intermediate state of Ca 2+ binding to the C2A domain of rabphilin 3A that suggests a different mechanism of ion interaction. We have also determined the structure of this domain in complex with PI(4,5)P 2 and IP 3 at resolutions of 1.75 and 1.9 Å, respectively, unveiling that the polybasic cluster formed by strands β3-β4 is involved in the interaction with the phosphoinositides. A comparative study demonstrates that the C2A domain is highly specific for PI(4,5)P 2 /PI (3,4,5)P 3 , whereas the C2B domain cannot discriminate among any of the diphosphorylated forms. Structural comparisons between C2A domains of rabphilin 3A and synaptotagmin 1 indicated the presence of a key glutamic residue in the polybasic cluster of synaptotagmin 1 that abolishes the interaction with PI (4,5)P 2 . Together, these results provide a structural explanation for the ability of different C2 domains to pull plasma and vesicle membranes close together in a Ca 2+ -dependent manner and reveal how this family of proteins can use subtle structural changes to modulate their sensitivity and specificity to various cellular signals.PIP2 | calcium | vesicle fusion C 2 modules are most commonly found in enzymes involved in lipid modifications and signal transduction and in proteins involved in membrane trafficking. They consist of 130 residues and share a common fold composed of two four-stranded β-sheets arranged in a compact β-sandwich connected by surface loops and helices (1-4). Many of these C2 domains have been demonstrated to function in a Ca 2+ -dependent membrane-binding manner and hence act as cellular Ca 2+ sensors. Calcium ions bind in a cupshaped invagination formed by three loops at one tip of the β-sandwich where the coordination spheres for the Ca 2+ ions are incomplete (5-7). This incomplete coordination sphere can be occupied by neutral and anionic (7-9) phospholipids, enabling the C2 domain to dock at the membrane.Previous work in our laboratory has shed light on the 3D structure of the C2 domain of PKCα in complex with both PS and PI(4,5)P 2 simultaneously (10). This revealed an additional lipidbinding site located in the polybasic region formed by β3-β4 strands that preferentially binds to PI(4,5)P 2 (11-15). This site is also conserved in a wide variety of C2 domains of topology I, for example synaptotagmins, rabphilin 3A, DOC2, and PI3KC2α (10,(16)(17)(18)(19). Given the importance of PI(4,5)P 2 for bringing the vesicle and plasma membranes together before exocytosis to ensure rapid and efficient fusion upon calcium influx (20-23), it is crucial to understand the molecular mechanisms beneath this event.Many studies have reported different and contradictory results about the membrane binding properties of C2A and C2B domains of synaptotagmin 1 and rabphilin 3A providing an unclear picture about how Ca 2+ and PI(4,5)P 2 combine to orchestrate the vesi...

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Section: Resultsmentioning

confidence: 76%

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Guillén

Ferrer-Orta

Buxaderas

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

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“…The final stage of the translocation mechanism likely includes an electrostatic attraction between DOC2B•Ca 2+ and the PLs near the PM 56,57 . This promotes specific PI(4,5)P 2 interactions and penetration of adjacent hydrophobic residues, some of which are exposed as a result of Ca 2+ activation, into the lipid bilayer 1,58 . The MD simulation suggests that charge neutralization in the Ca 2+ -binding site of the C2B domain by Ca 2+ reduces the electrostatic repulsion of the domain from the PM and promotes association with PI(4,5)P 2 , as recently described for syt1 27 and the constitutive PM localization of DOC2B D218,220N .…”

Section: Discussionmentioning

confidence: 99%

Phosphatidylinositol (4, 5)‐bisphosphate targets double C2 domain protein B to the plasma membrane

Michaeli

Gottfried

Bykhovskaia

et al. 2017

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DOC2B is a high-affinity Ca2+ sensor that translocates from the cytosol to the plasma membrane (PM) and promotes vesicle priming and fusion. However, the molecular mechanism underlying its translocation and targeting to the PM in living cells is not completely understood. DOC2B interacts in vitro with the PM components phosphatidylserine, phosphatidylinositol (4,5)-bisphosphate [PI(4,5)P2] and target SNAREs (t-SNAREs). Here we show that PI(4,5)P2 hydrolysis at the PM of living cells abolishes DOC2B translocation, whereas manipulations of t-SNAREs and other phosphoinositides have no effect. Moreover, we were able to redirect DOC2B to intracellular membranes by synthesizing PI(4,5)P2 in those membranes. Molecular dynamics simulations and mutagenesis in the calcium and PI(4,5)P2-binding sites strengthened our findings, demonstrating that both calcium and PI(4,5)P2 are required for the DOC2B–PM association and revealing multiple PI(4,5)P2–C2B interactions. In addition, we show that DOC2B translocation to the PM is ATP-independent, and occurs in a diffusion-like manner. Our data suggest that the Ca2+-triggered translocation of DOC2B is diffusion-driven and aimed at PI(4,5)P2-containing membranes.

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“…Strikingly, all homologs of TMEM24 contain an ~130 amino acid C2 domain that folds into an eight stranded β-sandwich found in over 100 proteins involved in vesicle trafficking and signal transduction. C2 domains bind phospholipids in a Ca 2+ -dependent manner and mediate protein-membrane associations that facilitate exocytosis of synaptic vesicles and insulin granules (Friedrich et al, 2010). Different pools of granules in β-cells have different Ca 2+ sensitivities.…”

Section: Discussionmentioning

confidence: 99%

Insulin Biosynthetic Interaction Network Component, TMEM24, Facilitates Insulin Reserve Pool Release

et al. 2013

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SUMMARY Insulin homeostasis in pancreatic β-cell is now recognized as a critical element in the progression of obesity and type II diabetes (T2D). Proteins that interact with insulin to direct its sequential synthesis, folding, trafficking and packaging into reserve granules to manage release in response to elevated glucose remains largely unknown. Using a conformation based approach combined with mass spectrometry we have now generated the insulin biosynthetic interaction network (insulin BIN), a proteomic roadmap in the β-cell that describes the sequential interacting partners of insulin along the secretory axis. The insulin BIN revealed an abundant C2 domain-containing transmembrane protein 24 (TMEM24) that manages glucose-stimulated insulin secretion from reserve pool of granules, a critical event impaired in patients with T2D. Identification of TMEM24 in the context of a comprehensive set of sequential insulin binding partners provides a molecular description of the insulin secretory pathway in β-cells.

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DOC2B, C2 Domains, and Calcium: A Tale of Intricate Interactions

Cited by 32 publications

References 71 publications

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Phosphatidylinositol (4, 5)‐bisphosphate targets double C2 domain protein B to the plasma membrane

Insulin Biosynthetic Interaction Network Component, TMEM24, Facilitates Insulin Reserve Pool Release

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DOC2B, C2 Domains, and Calcium: A Tale of Intricate Interactions

Cited by 32 publications

References 71 publications

Structural insights into the Ca 2+ and PI(4,5)P 2 binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Structural insights into the Ca 2+ and PI(4,5)P 2 binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Phosphatidylinositol (4, 5)‐bisphosphate targets double C2 domain protein B to the plasma membrane

Insulin Biosynthetic Interaction Network Component, TMEM24, Facilitates Insulin Reserve Pool Release

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Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1

Structural insights into the Ca ²⁺ and PI(4,5)P ₂ binding modes of the C2 domains of rabphilin 3A and synaptotagmin 1