Actomyosin interaction at low ATP concentrations
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- 作者：Manuela Maffei ; Emanuela Longa ; Antonio Sabatini…
- 关键词：In vitro motility assay ; ATP concentration ; Actomyosin interaction ; Gibbs free energy ; ATP hydrolysis
- 刊名：European Biophysics Journal
- 出版年：2017
- 出版时间：March 2017
- 年：2017
- 卷：46
- 期：2
- 页码：195-202
- 全文大小：
- 刊物类别：Physics and Astronomy
- 刊物主题：Biochemistry, general; Biological and Medical Physics, Biophysics; Cell Biology; Neurobiology; Membrane Biology; Nanotechnology;
- 出版者：Springer Berlin Heidelberg
- ISSN：1432-1017
- 卷排序：46
文摘
In vitro motility assay (IVMA) experiments were performed to analyze the movement of actin filaments sliding on a pavement of myosin molecules at different [ATP] and [ADP]. In standard experimental conditions at [ATP] = 2 mM, about 80% of the actin filaments move in unloaded conditions with a constant velocity. However, a fraction of at least 20% static actin filaments is always present. The accepted explanation is the occurrence of damaged “rigor”-like myosin heads that do not undergo the normal ATP-dependent cycling motion. However, in a series of IVMA experiments performed at different [ATP] we observed that the mobility of actin filaments increased with lowering [ATP]. We investigated the influence of [ATP] on the number of mobile actin filaments. IVMA experiments were performed at controlled nucleotide concentrations and the percentage of mobile filaments accurately determined by specific operator-guided software. The value of ΔGATP involved was determined. Results showed that the number of mobile actin filaments sliding on type 2B heavy meromyosin isoform (2B HMM) increased at very low [ATP] accompanied by less negative ΔGATP values. Similar results were obtained by increasing [ADP]. Performing experiments at the same [ATP] with different myosin types, we found a higher number of mobile actin filaments on slow type 1 HMM with respect to type 2B HMM while the highest number of mobile actin filaments was found on single-head myosin (S1 fraction). We also found that [ATP] did not influence the percentage of mobile actin filaments sliding on S1. Our results reveal novel aspects of actomyosin interaction.