RRC ID 20965
Author Uyeda TQ, Iwadate Y, Umeki N, Nagasaki A, Yumura S.
Title Stretching actin filaments within cells enhances their affinity for the myosin II motor domain.
Journal PLoS ONE
Abstract To test the hypothesis that the myosin II motor domain (S1) preferentially binds to specific subsets of actin filaments in vivo, we expressed GFP-fused S1 with mutations that enhanced its affinity for actin in Dictyostelium cells. Consistent with the hypothesis, the GFP-S1 mutants were localized along specific portions of the cell cortex. Comparison with rhodamine-phalloidin staining in fixed cells demonstrated that the GFP-S1 probes preferentially bound to actin filaments in the rear cortex and cleavage furrows, where actin filaments are stretched by interaction with endogenous myosin II filaments. The GFP-S1 probes were similarly enriched in the cortex stretched passively by traction forces in the absence of myosin II or by external forces using a microcapillary. The preferential binding of GFP-S1 mutants to stretched actin filaments did not depend on cortexillin I or PTEN, two proteins previously implicated in the recruitment of myosin II filaments to stretched cortex. These results suggested that it is the stretching of the actin filaments itself that increases their affinity for the myosin II motor domain. In contrast, the GFP-fused myosin I motor domain did not localize to stretched actin filaments, which suggests different preferences of the motor domains for different structures of actin filaments play a role in distinct intracellular localizations of myosin I and II. We propose a scheme in which the stretching of actin filaments, the preferential binding of myosin II filaments to stretched actin filaments, and myosin II-dependent contraction form a positive feedback loop that contributes to the stabilization of cell polarity and to the responsiveness of the cells to external mechanical stimuli.
Volume 6(10)
Pages e26200
Published 2011
DOI 10.1371/journal.pone.0026200
PII PONE-D-11-12001
PMID 22022566
PMC PMC3192770
MeSH Actin Cytoskeleton / metabolism* Dictyostelium / cytology* Dictyostelium / metabolism* Gene Knockout Techniques Green Fluorescent Proteins / metabolism Models, Biological Molecular Probes / metabolism Mutant Proteins / chemistry Mutant Proteins / metabolism Myosin Type II / chemistry* Myosin Type II / metabolism* Phalloidine / analogs & derivatives Phalloidine / metabolism Protein Structure, Tertiary Protein Transport Rhodamines / metabolism
IF 2.766
Times Cited 50
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