Oligomerization Affects the Ability of Human Cyclase-Associated Proteins 1 and 2 to Promote Actin Severing by Cofilins
Open Access
- 12 November 2019
- journal article
- research article
- Published by MDPI AG in International Journal of Molecular Sciences
- Vol. 20 (22), 5647
- https://doi.org/10.3390/ijms20225647
Abstract
Actin-depolymerizing factor (ADF)/cofilins accelerate actin turnover by severing aged actin filaments and promoting the dissociation of actin subunits. In the cell, ADF/cofilins are assisted by other proteins, among which cyclase-associated proteins 1 and 2 (CAP1,2) are particularly important. The N-terminal half of CAP has been shown to promote actin filament dynamics by enhancing ADF-/cofilin-mediated actin severing, while the central and C-terminal domains are involved in recharging the depolymerized ADP–G-actin/cofilin complexes with ATP and profilin. We analyzed the ability of the N-terminal fragments of human CAP1 and CAP2 to assist human isoforms of “muscle” (CFL2) and “non-muscle” (CFL1) cofilins in accelerating actin dynamics. By conducting bulk actin depolymerization assays and monitoring single-filament severing by total internal reflection fluorescence (TIRF) microscopy, we found that the N-terminal domains of both isoforms enhanced cofilin-mediated severing and depolymerization at similar rates. According to our analytical sedimentation and native mass spectrometry data, the N-terminal recombinant fragments of both human CAP isoforms form tetramers. Replacement of the original oligomerization domain of CAPs with artificial coiled-coil sequences of known oligomerization patterns showed that the activity of the proteins is directly proportional to the stoichiometry of their oligomerization; i.e., tetramers and trimers are more potent than dimers, which are more effective than monomers. Along with higher binding affinities of the higher-order oligomers to actin, this observation suggests that the mechanism of actin severing and depolymerization involves simultaneous or consequent and coordinated binding of more than one N-CAP domain to F-actin/cofilin complexes.Funding Information
- National Institutes of Health (P41 GM128577, R01 GM114666)
This publication has 85 references indexed in Scilit:
- ATP and ADP actin statesPeptide Science, 2012
- Serum Response Factor (SRF)-cofilin-actin signaling axis modulates mitochondrial dynamicsProceedings of the National Academy of Sciences of the United States of America, 2012
- Active maintenance of nuclear actin by importin 9 supports transcriptionProceedings of the National Academy of Sciences of the United States of America, 2012
- Remodeling of actin filaments by ADF/cofilin proteinsProceedings of the National Academy of Sciences of the United States of America, 2011
- ADF/cofilin proteins translocate to mitochondria during apoptosis but are not generally required for cell death signalingCell Death & Differentiation, 2011
- A Nucleotide State-sensing Region on ActinOnline Journal of Public Health Informatics, 2010
- A central role for the WH2 domain of Srv2/CAP in recharging actin monomers to drive actin turnover in vitro and in vivoCytoskeleton, 2010
- Coronin Switches Roles in Actin Disassembly Depending on the Nucleotide State of ActinMolecular Cell, 2009
- Reconstitution and Dissection of the 600-kDa Srv2/CAP ComplexOnline Journal of Public Health Informatics, 2009
- Rate constants for the reactions of ATP- and ADP-actin with the ends of actin filaments.The Journal of cell biology, 1986