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Single-molecule analysis reveals that regulatory light chains fine-tune skeletal myosin II function
Arnab Nayak1, Tianbang Wang1, Peter Franz2
1Institute of Molecular and Cell Physiology, Hannover Medical School, 30625 Hannover, Germany.
The Journal of Biological Chemistry
|April 11, 2020
Summary
Regulatory light chains (RLCs) fine-tune myosin II motor function. Swapping RLCs between fast and slow myosin heavy chains (MHCs) significantly altered actin filament sliding velocity, demonstrating RLCs
Area of Science:
- Muscle physiology
- Molecular motors
- Biochemistry
Background:
- Myosin II motors generate force for muscle contraction.
- Myosin heavy chain (MHC) isoforms contribute to diverse physiological functions.
- The role of myosin light chains (RLCs) in myosin specialization remains unclear.
Purpose of the Study:
- To investigate the contribution of different RLCs to myosin II functional diversification.
- To determine if RLCs fine-tune the chemo-mechanical properties of myosin motors.
Main Methods:
- Construction of chimeric myosin II motors by swapping RLCs between fast (MyHC-IId) and slow (MHC-I) isoforms.
- Ensemble molecule solution kinetics assays.
- Single-molecule optical trapping measurements.
Main Results:
- Actin filament sliding velocity was significantly altered by RLC swapping: a ~10-fold increase for slow myosin and a >3-fold decrease for fast myosin.
- RLC isoform significantly influenced the chemo-mechanical properties and mechanical output of both slow and fast myosins.
- Altered sliding speeds correlated with changes in myosin motor kinetics.
Conclusions:
- Regulatory light chains (RLCs) are critical for diversifying myosin II motor functions.
- RLCs play a crucial role in fine-tuning the mechanical output and performance of myosin motors.
- Myosin II functional specialization arises from the interplay between MHC and RLC isoforms.
Keywords:
actinactin filament gliding assaymolecular imagingmolecular motormuscle contractionmyosinmyosin IIoptical trappingoptical tweezersregulatory light chainsingle-molecule analysissingle-molecule biophysicssolution kineticsMore Related Videos
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