scholarly journals Single molecule analysis reveals the role of regulatory light chains in fine-tuning skeletal myosin-II function

2020 ◽  
Author(s):  
Arnab Nayak ◽  
Tianbang Wang ◽  
Peter Franz ◽  
Walter Steffen ◽  
Igor Chizhov ◽  
...  
Keyword(s):  
Single Molecule ◽  
Myosin Ii ◽  
Fine Tuning ◽  
Light Chains ◽  
Mhc I ◽  
Regulatory Light Chains ◽  
Fast Myosin ◽  
Skeletal Myosin ◽  
Myosin Motors ◽  
Outstanding Question

AbstractMyosin II is the main force generating motor during muscle contraction. Myosin II exists as different isoforms, involved in diverse physiological functions. The outstanding question is whether the myosin heavy chain (MHC) isoforms alone account for the distinct physiological properties. Unique sets of essential and regulatory light chains (RLCs) assembled with specific MHCs raises an interesting possibility of specialization of myosin functions via light chains (LCs). Here, we ask whether different RLCs contribute to the functional diversification. To investigate this, we generated chimeric motors by reconstituting MHC fast isoform (MyHC-IId) and slow isoform (MHC-I) with different light chain variants. As a result of RLCs swapping, actin filament sliding velocity increased by ∼ 10 fold for the slow myosin and decreased by >3 fold for the fast myosin. Ensemble molecule solution kinetics and single molecule optical trapping measurements provided in-depth insights into altered chemo mechanical properties of the myosin motors, thereby affecting the sliding speed. We find that both slow and fast myosins mechanical output is sensitive to the RLC isoform and propose that RLCs are crucial in fine-tuning of the myosin function.

scholarly journals Single-molecule analysis reveals that regulatory light chains fine-tune skeletal myosin II function

2020 ◽  
Vol 295 (20) ◽  
pp. 7046-7059 ◽  
Author(s):  
Arnab Nayak ◽  
Tianbang Wang ◽  
Peter Franz ◽  
Walter Steffen ◽  
Igor Chizhov ◽  
...  
Keyword(s):  
Single Molecule ◽  
Myosin Ii ◽  
Fine Tuning ◽  
Light Chains ◽  
Mhc I ◽  
Regulatory Light Chains ◽  
Fast Myosin ◽  
Skeletal Myosin ◽  
Myosin Motors ◽  
Outstanding Question

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.

scholarly journals Regulatory Light Chains Fine-Tune Skeletal Muscle Myosin-II Function

2021 ◽  
Vol 120 (3) ◽  
pp. 344a
Author(s):  
Arnab Nayak ◽  
Tianbang Wang ◽  
Peter Franz ◽  
Walter Steffen ◽  
Igor Chizhov ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Myosin Ii ◽  
Light Chains ◽  
Skeletal Muscle Myosin ◽  
Regulatory Light Chains ◽  
Muscle Myosin ◽  
Fine Tune

Myosin regulatory light chains are required to maintain the stability of myosin II and cellular integrity

2011 ◽  
Vol 434 (1) ◽  
pp. 171-180 ◽  
Author(s):  
Inju Park ◽  
Cecil Han ◽  
Sora Jin ◽  
Boyeon Lee ◽  
Heejin Choi ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Interaction Analysis ◽  
Cell Structure ◽  
Myosin Ii ◽  
Actin Binding ◽  
Light Chains ◽  
Loss Of Function ◽  
Regulatory Light Chains ◽  
Mhc Ii ◽  
Nih 3T3

Myosin II is an actin-binding protein composed of MHC (myosin heavy chain) IIs, RLCs (regulatory light chains) and ELCs (essential light chains). Myosin II expressed in non-muscle tissues plays a central role in cell adhesion, migration and division. The regulation of myosin II activity is known to involve the phosphorylation of RLCs, which increases the Mg2+-ATPase activity of MHC IIs. However, less is known about the details of RLC–MHC II interaction or the loss-of-function phenotypes of non-muscle RLCs in mammalian cells. In the present paper, we investigate three highly conserved non-muscle RLCs of the mouse: MYL (myosin light chain) 12A (referred to as MYL12A), MYL12B and MYL9 (MYL12A/12B/9). Proteomic analysis showed that all three are associated with the MHCs MYH9 (NMHC IIA) and MYH10 (NMHC IIB), as well as the ELC MYL6, in NIH 3T3 fibroblasts. We found that knockdown of MYL12A/12B in NIH 3T3 cells results in striking changes in cell morphology and dynamics. Remarkably, the levels of MYH9, MYH10 and MYL6 were reduced significantly in knockdown fibroblasts. Comprehensive interaction analysis disclosed that MYL12A, MYL12B and MYL9 can all interact with a variety of MHC IIs in diverse cell and tissue types, but do so optimally with non-muscle types of MHC II. Taken together, our study provides direct evidence that normal levels of non-muscle RLCs are essential for maintaining the integrity of myosin II, and indicates that the RLCs are critical for cell structure and dynamics.

scholarly journals Hybrids of Physarum myosin light chains and desensitized scallop myofibrils.

1981 ◽  
Vol 90 (2) ◽  
pp. 408-414 ◽  
Author(s):  
V T Nachmias
Keyword(s):  
Light Chain ◽  
Myosin Light Chain ◽  
Myosin Atpase ◽  
Light Chains ◽  
Myosin Light Chains ◽  
Free Calcium ◽  
Standard Methods ◽  
Regulatory Light Chains ◽  
Skeletal Myosin

The two light chains of Physarum myosin have been purified in a 1:1 ratio with a yield of 0.5-1 mg/100 g of plasmodium and a purity of 40-70%; the major contaminant is a 42,000-dalton protein. The 17,700 Mr Physarum myosin light chain (PhLC1) binds to scallop myofibrils, providing the regulatory light chains (ScRLC) have been removed. The 16,500 Mr light (PhLC2) does not bind to scallop myofibrils. The calcium control of scallop myosin ATPase is lost by the removal of one of the two ScRLC's and restored equally well by the binding of either PhLC1 or rabbit skeletal myosin light chains. When both ScRLC's are removed, replacement by two plasmodial light chains does not restore calcium control as platelet or scallop light chains do. Purified plasmodial actomyosin does not bind calcium in 10(-6) M free calcium, 1 mM MgCl2. No tropomyosin was isolated from Physarum by standard methods. Because the Physarum myosin light chains can substitute only partially for light chains from myosin linked systems, because calcium does not bind to the actomyosin, and because tropomyosin is apparently absent, the regulation of plasmodial actomyosin by micromolar Ca++ may involve other mechanisms, possibly phosphorylation.

scholarly journals Differential localization of non-muscle myosin II isoforms and phosphorylated regulatory light chains in human MRC-5 fibroblasts

FEBS Letters ◽  
2001 ◽  
Vol 509 (3) ◽  
pp. 365-369 ◽  
Author(s):  
Takayuki Saitoh ◽  
Shuhei Takemura ◽  
Kozue Ueda ◽  
Hiroshi Hosoya ◽  
Masafumi Nagayama ◽  
...  
Keyword(s):  
Myosin Ii ◽  
Light Chains ◽  
Regulatory Light Chains ◽  
Differential Localization ◽  
Muscle Myosin
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