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Analysis of flexural rigidity of actin filaments propelled by surface adsorbed myosin motors.

Bengtsson E, Persson M, Månsson A - Cytoskeleton (Hoboken) (2013)

Bottom Line: Actin filaments are central components of the cytoskeleton and the contractile machinery of muscle.The filaments are known to exist in a range of conformational states presumably with different flexural rigidity and thereby different persistence lengths.Our results analyze the approaches proposed previously to measure the persistence length from the statistics of the winding paths of actin filaments that are propelled by surface-adsorbed myosin motor fragments in the in vitro motility assay.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.

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Related in: MedlinePlus

Effects of cut-off angle and sliding distance between measurements. (A) Cut-off values given in terms of the number of standard deviations for simulations without uniform random errors. (B) Same analysis as in A but with uniform random errors in about 2.5% of the updates of the sliding direction between subsequent measurement points along a filament path. Digitization effects considered neither in A nor in B. Theoretical persistence length in simulations, 10 μm.
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fig05: Effects of cut-off angle and sliding distance between measurements. (A) Cut-off values given in terms of the number of standard deviations for simulations without uniform random errors. (B) Same analysis as in A but with uniform random errors in about 2.5% of the updates of the sliding direction between subsequent measurement points along a filament path. Digitization effects considered neither in A nor in B. Theoretical persistence length in simulations, 10 μm.

Mentions: A more detailed analysis was also performed of the effect of the cut-off angle on the final outcome of the analysis. The relevant scale in this case was the standard deviation (given by Eq. 2; see below), i.e., for a range of conditions, we plot estimated persistence lengths against different cut-off values expressed in terms of the number of standard deviations. Data in Fig. 5 are based on simulated results for three different sliding distances between image frames, i.e., for three different ratios vfΔt/LPtheor. In Fig. 5A, no abrupt changes in sliding direction are assumed. Data in Fig. 5B include such abrupt simulated changes, as described in “Materials and Methods” section. It can be seen from Fig. 5A that, in the absence of abrupt changes, the cut-off value should be larger than (Eq. 2) as lower cut-off values lead to overestimated LP-values due to elimination of the most curved filament paths from the analysis. The data in Fig. 5B, including abrupt changes in <2.5% of the updates of the sliding directions between data points, would clearly benefit from as low cut-off value as possible close to 3SD in order to prevent the abrupt changes to cause an underestimation of the persistence length. However, it is also clear that only a small error (less than ∼1 µm) is introduced if the cut-off value is in the range of 3–5 standard deviations.


Analysis of flexural rigidity of actin filaments propelled by surface adsorbed myosin motors.

Bengtsson E, Persson M, Månsson A - Cytoskeleton (Hoboken) (2013)

Effects of cut-off angle and sliding distance between measurements. (A) Cut-off values given in terms of the number of standard deviations for simulations without uniform random errors. (B) Same analysis as in A but with uniform random errors in about 2.5% of the updates of the sliding direction between subsequent measurement points along a filament path. Digitization effects considered neither in A nor in B. Theoretical persistence length in simulations, 10 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230416&req=5

fig05: Effects of cut-off angle and sliding distance between measurements. (A) Cut-off values given in terms of the number of standard deviations for simulations without uniform random errors. (B) Same analysis as in A but with uniform random errors in about 2.5% of the updates of the sliding direction between subsequent measurement points along a filament path. Digitization effects considered neither in A nor in B. Theoretical persistence length in simulations, 10 μm.
Mentions: A more detailed analysis was also performed of the effect of the cut-off angle on the final outcome of the analysis. The relevant scale in this case was the standard deviation (given by Eq. 2; see below), i.e., for a range of conditions, we plot estimated persistence lengths against different cut-off values expressed in terms of the number of standard deviations. Data in Fig. 5 are based on simulated results for three different sliding distances between image frames, i.e., for three different ratios vfΔt/LPtheor. In Fig. 5A, no abrupt changes in sliding direction are assumed. Data in Fig. 5B include such abrupt simulated changes, as described in “Materials and Methods” section. It can be seen from Fig. 5A that, in the absence of abrupt changes, the cut-off value should be larger than (Eq. 2) as lower cut-off values lead to overestimated LP-values due to elimination of the most curved filament paths from the analysis. The data in Fig. 5B, including abrupt changes in <2.5% of the updates of the sliding directions between data points, would clearly benefit from as low cut-off value as possible close to 3SD in order to prevent the abrupt changes to cause an underestimation of the persistence length. However, it is also clear that only a small error (less than ∼1 µm) is introduced if the cut-off value is in the range of 3–5 standard deviations.

Bottom Line: Actin filaments are central components of the cytoskeleton and the contractile machinery of muscle.The filaments are known to exist in a range of conformational states presumably with different flexural rigidity and thereby different persistence lengths.Our results analyze the approaches proposed previously to measure the persistence length from the statistics of the winding paths of actin filaments that are propelled by surface-adsorbed myosin motor fragments in the in vitro motility assay.

View Article: PubMed Central - PubMed

Affiliation: Faculty of Health and Life Sciences, Linnaeus University, Kalmar, Sweden.

Show MeSH
Related in: MedlinePlus