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In Vitro Polymerization of F-actin on Early Endosomes
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The bacterial effector VopL organizes actin into filament-like structures
Jacob A Zahm1, Shae B Padrick, Zhucheng Chen
1Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
Cell
|October 15, 2013
Summary
Vibrio parahaemolyticus VopL protein
Area of Science:
- Microbiology
- Cell Biology
- Structural Biology
Background:
- Vibrio parahaemolyticus VopL is an effector protein.
- VopL nucleates actin filaments and has a VopL C-terminal domain (VCD) and three WASP homology 2 (WH2) motifs.
Purpose of the Study:
- To determine the crystal structure of the VCD dimer bound to actin.
- To elucidate the mechanism of VopL-mediated actin nucleation.
Main Methods:
- X-ray crystallography
- Structural analysis of VopL C-terminal domain (VCD) bound to actin.
Main Results:
- The crystal structure reveals the VCD dimer organizes three actin monomers in a filament-like arrangement.
- WH2 motifs can bind these actin monomers without steric hindrance.
- This organization facilitates templating of new actin subunit addition.
Conclusions:
- VopL nucleates actin by creating filament-like structures organized by the VCD and monomers delivered by WH2 motifs.
- This mechanism is analogous to actin nucleation by Arp2/3 complex and formins.
- Monomer organization into filament-like structures is a key feature of actin nucleation.
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