Omayma Y Al Azzam, Janie C Watts, Justin E Reynolds, Juliana E Davis, Dana N Reinemann
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引用次数: 1
Abstract
Introduction: Myosin II has been investigated with optical trapping, but single motor-filament assay arrangements are not reflective of the complex cellular environment. To understand how myosin interactions propagate up in scale to accomplish system force generation, we devised a novel actomyosin ensemble optical trapping assay that reflects the hierarchy and compliancy of a physiological environment and is modular for interrogating force effectors.
Methods: Hierarchical actomyosin bundles were formed in vitro. Fluorescent template and cargo actin filaments (AF) were assembled in a flow cell and bundled by myosin. Beads were added in the presence of ATP to bind the cargo AF and activate myosin force generation to be measured by optical tweezers.
Results: Three force profiles resulted across a range of myosin concentrations: high force with a ramp-plateau, moderate force with sawtooth movement, and baseline. The three force profiles, as well as high force output, were recovered even at low solution concentration, suggesting that myosins self-optimize within AFs. Individual myosin steps were detected in the ensemble traces, indicating motors are taking one step at a time while others remain engaged in order to sustain productive force generation.
Conclusions: Motor communication and system compliancy are significant contributors to force output. Environmental conditions, motors taking individual steps to sustain force, the ability to backslip, and non-linear concentration dependence of force indicate that the actomyosin system contains a force-feedback mechanism that senses the local cytoskeletal environment and communicates to the individual motors whether to be in a high or low duty ratio mode.
Supplementary information: The online version contains supplementary material available at 10.1007/s12195-022-00731-1.
期刊介绍：
The field of cellular and molecular bioengineering seeks to understand, so that we may ultimately control, the mechanical, chemical, and electrical processes of the cell. A key challenge in improving human health is to understand how cellular behavior arises from molecular-level interactions. CMBE, an official journal of the Biomedical Engineering Society, publishes original research and review papers in the following seven general areas:
Molecular: DNA-protein/RNA-protein interactions, protein folding and function, protein-protein and receptor-ligand interactions, lipids, polysaccharides, molecular motors, and the biophysics of macromolecules that function as therapeutics or engineered matrices, for example.
Cellular: Studies of how cells sense physicochemical events surrounding and within cells, and how cells transduce these events into biological responses. Specific cell processes of interest include cell growth, differentiation, migration, signal transduction, protein secretion and transport, gene expression and regulation, and cell-matrix interactions.
Mechanobiology: The mechanical properties of cells and biomolecules, cellular/molecular force generation and adhesion, the response of cells to their mechanical microenvironment, and mechanotransduction in response to various physical forces such as fluid shear stress.
Nanomedicine: The engineering of nanoparticles for advanced drug delivery and molecular imaging applications, with particular focus on the interaction of such particles with living cells. Also, the application of nanostructured materials to control the behavior of cells and biomolecules.
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