A novel mode of capping protein-regulation by twinfilin
Abstract
Cellular actin assembly is controlled at the barbed ends of actin filaments, where capping protein (CP) limits polymerization. Twinfilin is a conserved in vivo binding partner of CP, yet the significance of this interaction has remained a mystery. Here, we discover that the C-terminal tail of Twinfilin harbors a CP-interacting (CPI) motif, identifying it as a novel CPI-motif protein. Twinfilin and the CPI-motif protein CARMIL have overlapping binding sites on CP. Further, Twinfilin binds competitively with CARMIL to CP, protecting CP from barbed-end displacement by CARMIL. Twinfilin also accelerates dissociation of the CP inhibitor V-1, restoring CP to an active capping state. Knockdowns of Twinfilin and CP each cause similar defects in cell morphology, and elevated Twinfilin expression rescues defects caused by CARMIL hyperactivity. Together, these observations define Twinfilin as the first ‘pro-capping’ ligand of CP and lead us to propose important revisions to our understanding of the CP regulatory cycle.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Oct 23, 2018
- Source ID
- 10.7554/elife.41313
Entities
People
- Adam B Johnston
- Avital Simone
- Britney Johnson
- Bruce L Goode
- Denise M Hilton
- Gaya K. Amarasinghe
- John A Cooper
- Meghan T Harris
- Patrick Mcconnell
Organizations
- Brandeis University
- Defense Threat Reduction Agency
- National Institutes of Health
- National Science Foundation
- Washington University in St. Louis