Key result
The synthetic myosin II-based nanomachine assembled with the Ca2+-insensitive gelsolin fragment TL40 exhibited identical mechanical performance compared to the standard Ca2+-dependent assembly.
Why the study?
Investigating Ca2+-dependent regulation mechanisms of sarcomeric proteins with an original synthetic nanomachine was prevented by the inability to preserve Ca2+ as a free parameter.
Absolute Event Rate: 15.88% vs 15.41%
p-value: p=>0.1
The use of a Ca2+-insensitive gelsolin fragment preserves the mechanical performance of a myosin II-based nanomachine while allowing Ca2+ concentration to be a free parameter for future studies of sarcomeric proteins.
Simplifies Ca2+-independent myosin nanomachine assembly; extends basic cardiac mechanics tools while leaving clinical translation open.
The emergent properties of the array arrangement of the molecular motor myosin II in the sarcomere of the striated muscle, generation of steady force and shortening, can be studied in vitro with a synthetic nanomachine, made by an ensemble of eight HMM myosin fragments from rabbit psoas muscle carried on a piezoelectric nanopositioner and brought to interact with a properly oriented actin filament attached via gelsolin (a Ca 2+ -regulated actin binding protein) to a bead trapped by a Dual Laser Optical Tweezers. The application of the original version of the nanomachine to investigation of the Ca 2+ -dependent regulation mechanisms of the other sarcomeric (regulatory or cytoskeleton) proteins, adding them on at a time, was anyway prevented by the impossibility to preserve Ca 2+ as a free parameter. Here the nanomachine is implemented by assembling the bead-attached actin filament with the Ca 2+ -insensitive gelsolin fragment TL40. The performance of the nanomachine is determined either in the absence or in the presence of 0.1 mM Ca 2+ (the concentration required for BTA preparation with gelsolin). The nanomachine exhibits a maximum power output of 5.4 aW, independently of [Ca 2+ ], opening the possibility for future studies of the Ca 2+ -dependent function/dysfunction of regulatory and cytoskeletal proteins.
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Pertici et al. (2020) studied this question. Ca2+-insensitive gelsolin fragment TL40 (Ca2+-free solution) vs. 0.1 mM Ca2+ (gelsolin) was evaluated on Maximum steady isometric force (F0) in pN (p=>0.1). The synthetic myosin II-based nanomachine assembled with the Ca2+-insensitive gelsolin fragment TL40 exhibited identical mechanical performance compared to the standard Ca2+-dependent assembly.
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