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Actin cable distribution and dynamics arising from cross-linking, motor pulling, and filament turnover.

Tang H, Laporte D, Vavylonis D - Mol. Biol. Cell (2014)

Bottom Line: Our simulations reproduce the particular actin cable structures in myoVΔ cells and predict the effect of increased myosin V pulling.Increasing cross-linking parameters generates thicker actin cables.It also leads to antiparallel and parallel phases with straight or curved cables, consistent with observations of cells overexpressing α-actinin.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Lehigh University, Bethlehem, PA 18015.

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Model mechanism. (A) Images of actin cables in fission yeast (inverted black and white). GFP-CHD–tagged actin showing structures of actin cables (black lines) and actin patches (black dots). (B) A single actin filament is described by a bead-spring model. (C) The effect of cross-linking proteins that link neighboring actin filaments into bundles is represented as finite-range spring interactions. (D) Tea1p/Tea4p landmark proteins at the cell tip recruit For3p molecules to form clusters, which polymerize actin subunits into actin filaments. This is represented by growth of semiflexible polymers from fixed positions at cell tips. (E) Myosin V pulls actin filaments by carrying or anchoring on heavy loads. This is represented by tangential forces along actin filaments.
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Figure 1: Model mechanism. (A) Images of actin cables in fission yeast (inverted black and white). GFP-CHD–tagged actin showing structures of actin cables (black lines) and actin patches (black dots). (B) A single actin filament is described by a bead-spring model. (C) The effect of cross-linking proteins that link neighboring actin filaments into bundles is represented as finite-range spring interactions. (D) Tea1p/Tea4p landmark proteins at the cell tip recruit For3p molecules to form clusters, which polymerize actin subunits into actin filaments. This is represented by growth of semiflexible polymers from fixed positions at cell tips. (E) Myosin V pulls actin filaments by carrying or anchoring on heavy loads. This is represented by tangential forces along actin filaments.

Mentions: Budding and fission yeast cells are ideal for quantitative studies of actin organization because they are amenable to genetic modifications and microscopic imaging. Their interphase actin cytoskeleton is organized into two distinct components (Figure 1A): actin patches (nucleated by the Arp2/3 complex) and actin cables (nucleated by formins) (Drake and Vavylonis, 2010; Kovar et al., 2011). The actin cables are bundles of ∼10 actin filaments (Kamasaki et al., 2005) that help cells establish polarized growth by providing tracks to transport secretory vesicles and organelles toward the growing part of the cell in both yeasts and plants (Vidali et al., 2009; Wu et al., 2010). In this work, we develop a model of actin cables in fission yeast that has a simple tube-like shape and a single actin cable nucleator, formin For3p. In fission yeast, actin cables growing from either tip can meet and cross-link with one another and form different morphologies, depending on the cross-linking dynamics. Of importance, actin cables are critical for polarized growth by supporting myosin cargo directional motility.


Actin cable distribution and dynamics arising from cross-linking, motor pulling, and filament turnover.

Tang H, Laporte D, Vavylonis D - Mol. Biol. Cell (2014)

Model mechanism. (A) Images of actin cables in fission yeast (inverted black and white). GFP-CHD–tagged actin showing structures of actin cables (black lines) and actin patches (black dots). (B) A single actin filament is described by a bead-spring model. (C) The effect of cross-linking proteins that link neighboring actin filaments into bundles is represented as finite-range spring interactions. (D) Tea1p/Tea4p landmark proteins at the cell tip recruit For3p molecules to form clusters, which polymerize actin subunits into actin filaments. This is represented by growth of semiflexible polymers from fixed positions at cell tips. (E) Myosin V pulls actin filaments by carrying or anchoring on heavy loads. This is represented by tangential forces along actin filaments.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4230589&req=5

Figure 1: Model mechanism. (A) Images of actin cables in fission yeast (inverted black and white). GFP-CHD–tagged actin showing structures of actin cables (black lines) and actin patches (black dots). (B) A single actin filament is described by a bead-spring model. (C) The effect of cross-linking proteins that link neighboring actin filaments into bundles is represented as finite-range spring interactions. (D) Tea1p/Tea4p landmark proteins at the cell tip recruit For3p molecules to form clusters, which polymerize actin subunits into actin filaments. This is represented by growth of semiflexible polymers from fixed positions at cell tips. (E) Myosin V pulls actin filaments by carrying or anchoring on heavy loads. This is represented by tangential forces along actin filaments.
Mentions: Budding and fission yeast cells are ideal for quantitative studies of actin organization because they are amenable to genetic modifications and microscopic imaging. Their interphase actin cytoskeleton is organized into two distinct components (Figure 1A): actin patches (nucleated by the Arp2/3 complex) and actin cables (nucleated by formins) (Drake and Vavylonis, 2010; Kovar et al., 2011). The actin cables are bundles of ∼10 actin filaments (Kamasaki et al., 2005) that help cells establish polarized growth by providing tracks to transport secretory vesicles and organelles toward the growing part of the cell in both yeasts and plants (Vidali et al., 2009; Wu et al., 2010). In this work, we develop a model of actin cables in fission yeast that has a simple tube-like shape and a single actin cable nucleator, formin For3p. In fission yeast, actin cables growing from either tip can meet and cross-link with one another and form different morphologies, depending on the cross-linking dynamics. Of importance, actin cables are critical for polarized growth by supporting myosin cargo directional motility.

Bottom Line: Our simulations reproduce the particular actin cable structures in myoVΔ cells and predict the effect of increased myosin V pulling.Increasing cross-linking parameters generates thicker actin cables.It also leads to antiparallel and parallel phases with straight or curved cables, consistent with observations of cells overexpressing α-actinin.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Lehigh University, Bethlehem, PA 18015.

Show MeSH
Related in: MedlinePlus