Tittel, Janine and Welz, Tobias and Czogalla, Aleksander and Dietrich, Susanne and Samol-Wolf, Annette and Schulte, Markos and Schwille, Petra and Weidemann, Thomas and Kerkhoff, Eugen (2015) Membrane Targeting of the Spir.Formin Actin Nucleator Complex Requires a Sequential Handshake of Polar Interactions. JOURNAL OF BIOLOGICAL CHEMISTRY, 290 (10). pp. 6428-6444. ISSN 0021-9258, 1083-351X
Full text not available from this repository. (Request a copy)Abstract
Spir and formin (FMN)-type actin nucleators initiate actin polymerization at vesicular membranes necessary for long range vesicular transport processes. Here we studied in detail the membrane binding properties and protein/protein interactions that govern the assembly of the membrane-associated SpirFMN complex. Using biomimetic membrane models we show that binding of the C-terminal Spir-2 FYVE-type zinc finger involves both the presence of negatively charged lipids and hydrophobic contributions from the turret loop that intrudes the lipid bilayer. In solution, we uncovered a yet unknown intramolecular interaction between the Spir-2 FYVE-type domain and the N-terminal kinase non-catalytic C-lobe domain (KIND) that could not be detected in the membrane-bound state. Interestingly, we found that the intramolecular Spir-2 FYVE/KIND and the trans-regulatory Fmn-2-FSI/Spir-2-KIND interactions are competitive. We therefore characterized co-expressed Spir-2 and Fmn-2 fluorescent protein fusions in living cells by fluorescence cross-correlation spectroscopy. The data corroborate a model according to which Spir-2 exists in two different states, a cytosolic monomeric conformation and a membrane-bound state in which the KIND domain is released and accessible for subsequent Fmn-2 recruitment. This sequence of interactions mechanistically couples membrane binding of Spir to the recruitment of FMN, a pivotal step for initiating actin nucleation at vesicular membranes.
| Item Type: | Article |
|---|---|
| Uncontrolled Keywords: | FLUORESCENCE CORRELATION SPECTROSCOPY; CROSS-CORRELATION SPECTROSCOPY; FYVE DOMAIN; PHOSPHATIDYLINOSITOL 3-PHOSPHATE; CELLULAR MEMBRANES; VESICLE TRANSPORT; CRYSTAL-STRUCTURE; KINASE FUNCTION; C-LOBE; PROTEIN; |
| Subjects: | 600 Technology > 610 Medical sciences Medicine |
| Divisions: | Medicine > Lehrstuhl für Neurologie |
| Depositing User: | Dr. Gernot Deinzer |
| Date Deposited: | 22 Jul 2019 14:15 |
| Last Modified: | 22 Jul 2019 14:15 |
| URI: | https://pred.uni-regensburg.de/id/eprint/5801 |
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