1. Single-molecule analysis reveals that regulatory light chains fine-tune skeletal myosin II function
- Author
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Arnab Nayak, Igor Chizhov, Georgios Tsiavaliaris, Mamta Amrute-Nayak, Walter Steffen, Tianbang Wang, and Peter Franz
- Subjects
0301 basic medicine ,Gene isoform ,Myosin Light Chains ,Optical Tweezers ,macromolecular substances ,Immunoglobulin light chain ,Major histocompatibility complex ,Biochemistry ,03 medical and health sciences ,Myosin ,Molecular motor ,medicine ,Animals ,Molecular Biology ,Actin ,Myosin Type II ,030102 biochemistry & molecular biology ,biology ,Chemistry ,Cell Biology ,Isoenzymes ,Actin Cytoskeleton ,030104 developmental biology ,biology.protein ,Biophysics ,Rabbits ,medicine.symptom ,Molecular Biophysics ,Function (biology) ,Muscle contraction - Abstract
Myosin II is the main force-generating motor during muscle contraction. Myosin II exists as different isoforms that are involved in diverse physiological functions. One outstanding question is whether the myosin heavy chain (MHC) isoforms alone account for these distinct physiological properties. Unique sets of essential and regulatory light chains (RLCs) are known to assemble with specific MHCs, raising the intriguing possibility that light chains contribute to specialized myosin functions. Here, we asked whether different RLCs contribute to this functional diversification. To this end, we generated chimeric motors by reconstituting the MHC fast isoform (MyHC-IId) and slow isoform (MHC-I) with different light-chain variants. As a result of the RLC swapping, actin filament sliding velocity increased by ∼10-fold for the slow myosin and decreased by >3-fold for the fast myosin. Results from ensemble molecule solution kinetics and single-molecule optical trapping measurements provided in-depth insights into altered chemo-mechanical properties of the myosin motors that affect the sliding speed. Notably, we found that the mechanical output of both slow and fast myosins is sensitive to the RLC isoform. We therefore propose that RLCs are crucial for fine-tuning the myosin function.
- Published
- 2020