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-Structure paper
Title | Structure of the Lifeact-F-actin complex. |
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Journal, issue, pages | PLoS Biol, Vol. 18, Issue 11, Page e3000925, Year 2020 |
Publish date | Nov 20, 2020 |
Authors | Alexander Belyy / Felipe Merino / Oleg Sitsel / Stefan Raunser / |
PubMed Abstract | Lifeact is a short actin-binding peptide that is used to visualize filamentous actin (F-actin) structures in live eukaryotic cells using fluorescence microscopy. However, this popular probe has been ...Lifeact is a short actin-binding peptide that is used to visualize filamentous actin (F-actin) structures in live eukaryotic cells using fluorescence microscopy. However, this popular probe has been shown to alter cellular morphology by affecting the structure of the cytoskeleton. The molecular basis for such artefacts is poorly understood. Here, we determined the high-resolution structure of the Lifeact-F-actin complex using electron cryo-microscopy (cryo-EM). The structure reveals that Lifeact interacts with a hydrophobic binding pocket on F-actin and stretches over 2 adjacent actin subunits, stabilizing the DNase I-binding loop (D-loop) of actin in the closed conformation. Interestingly, the hydrophobic binding site is also used by actin-binding proteins, such as cofilin and myosin and actin-binding toxins, such as the hypervariable region of TccC3 (TccC3HVR) from Photorhabdus luminescens and ExoY from Pseudomonas aeruginosa. In vitro binding assays and activity measurements demonstrate that Lifeact indeed competes with these proteins, providing an explanation for the altering effects of Lifeact on cell morphology in vivo. Finally, we demonstrate that the affinity of Lifeact to F-actin can be increased by introducing mutations into the peptide, laying the foundation for designing improved actin probes for live cell imaging. |
External links | PLoS Biol / PubMed:33216759 / PubMed Central |
Methods | EM (helical sym.) |
Resolution | 3.5 Å |
Structure data | EMDB-11721, PDB-7ad9: |
Chemicals | ChemComp-ADP: ChemComp-MG: ChemComp-PO4: |
Source |
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Keywords | STRUCTURAL PROTEIN / Cytoskeleton / Actin / Lifeact / labelling. |