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Title: Single-molecule imaging of IQGAP1 regulating actin filament dynamics
IQGAP is a conserved family of actin-binding proteins with essential roles in cell motility, cytokinesis, and cell adhesion, yet there remains a limited understanding of how IQGAP proteins directly influence actin filament dynamics. To close this gap, we used single-molecule and single-filament total internal reflection fluorescence microscopy to observe IQGAP regulating actin dynamics in real time. To our knowledge, this is the first study to do so. Our results demonstrate that full-length human IQGAP1 forms dimers that stably bind to actin filament sides and transiently cap barbed ends. These interactions organize filaments into thin bundles, suppress barbed end growth, and inhibit filament disassembly. Surprisingly, each activity depends on distinct combinations of IQGAP1 domains and/or dimerization, suggesting that different mechanisms underlie each functional effect on actin. These observations have important implications for how IQGAP functions as an actin regulator in vivo and how it may be regulated in different biological settings.  more » « less
Award ID(s):
2011846
PAR ID:
10506791
Author(s) / Creator(s):
; ; ;
Editor(s):
Blanchoin, Laurent
Publisher / Repository:
American Society for Cell Biology
Date Published:
Journal Name:
Molecular Biology of the Cell
Volume:
33
Issue:
1
ISSN:
1059-1524
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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