The Regulatory Domain of the Myosin Head Behaves as a Rigid Lever

Baumann, Bruce A.J.; Hambly, Brett D.; Hideg, Kálmán; Fajer, Piotr G.

doi:10.1021/bi002731h

Cited by 17 publications

(16 citation statements)

References 52 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Fluorescence polarization investigation of both S1 and muscle fibers showed a nucleotide-and actin-dependent change in the orientation of the ELC-180 (9,23). The electron paramagnetic resonance measurements detected a change in the mobility of a spin probe attached in reconstituted myosin filaments (25). However, despite the accumulated information, the interpretation of these findings is limited by the use of fragmentary protein systems and a single labeling site in the ELC.…”

Section: Discussionmentioning

confidence: 99%

Response of Rigor Cross-bridges to Stretch Detected by Fluorescence Lifetime Imaging Microscopy of Myosin Essential Light Chain in Skeletal Muscle Fibers

Ushakov

Caorsi

Ibanez-Garcia

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

We applied fluorescence lifetime imaging microscopy to map the microenvironment of the myosin essential light chain (ELC) in permeabilized skeletal muscle fibers. Four ELC mutants containing a single cysteine residue at different positions in the C-terminal half of the protein (ELC-127, ELC-142, ELC-160, and ELC-180) were generated by site-directed mutagenesis, labeled with 7-diethylamino-3-((((2-iodoacetamido)-ethyl)amino)carbonyl)coumarin, and introduced into permeabilized rabbit psoas fibers. Binding to the myosin heavy chain was associated with a large conformational change in the ELC. When the fibers were moved from relaxation to rigor, the fluorescence lifetime increased for all label positions. However, when 1% stretch was applied to the rigor fibers, the lifetime decreased for ELC-127 and ELC-180 but did not change for ELC-142 and ELC-160. The differential change of fluorescence lifetime demonstrates the shift in position of the C-terminal domain of ELC with respect to the heavy chain and reveals specific locations in the lever arm region sensitive to the mechanical strain propagating from the actin-binding site to the lever arm.The function of striated muscles is brought about by the relative sliding of actin and myosin filaments. Muscle myosin is a hexameric protein, assembled from two heavy chains, each bearing a regulatory and an essential light chain (RLC 3 and ELC, respectively). The heavy chains consist of a long tail region responsible for the formation of a filament structure and a globular head containing the catalytic domain and the lever arm, which binds the light chains. The interaction of the globular head with actin filament facilitates the release of ATP hydrolysis products from myosin. The accompanying structural changes result in rotation of the lever arm (1-3).The molecular details of the change in position of the lever arm with respect to the catalytic domain were revealed by crystallographic studies of myosin head in the presence of nucleotide analogues in the ATPase pocket (2). Although there is still no crystal structure of actomyosin available, x-ray diffraction (4) and fluorescence polarization studies of both RLC (5-7) and ELC (8) confirmed rotation of the lever arm when comparing active, relaxed, and rigor muscle fibers. However, the angular changes were substantially different from those expected by crystallography. This discrepancy could be due to the crystal packing or the use of a truncated form of myosin head, which lacked most of the lever arm. In addition, the fluorescence polarization studies were focused on the distal part of the lever arm, which is remote from the catalytic domain. Therefore, the proximal part of the lever arm, which forms an interface with the catalytic domain, is of particular interest. The fluorescence polarization study of this region (9) showed its reorientation when muscle fibers were moved from relaxation to rigor. However, only a single labeling site was used, and the details of this reorientation are still not clear.The aim of this work ...

show abstract

Section: Discussionmentioning

confidence: 99%

Response of Rigor Cross-bridges to Stretch Detected by Fluorescence Lifetime Imaging Microscopy of Myosin Essential Light Chain in Skeletal Muscle Fibers

Ushakov

Caorsi

Ibanez-Garcia

et al. 2011

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…Phosphorylation of cardiac MyBPC releases the S2 region, which is thought to allow the myosin crossbridges to reach out and interact more efficiently with actin, increasing force generation and systolic tension [48][49][50]. Flexibility of the myosin head, both as a whole, and within its two domains, is a necessary requirement for efficient force generation [51][52][53]. The extent of phosphorylation required to abolish the interaction with S2 remains unclear [4].…”

Section: Figmentioning

confidence: 99%

Myosin binding protein C: Structural abnormalities in familial hypertrophic cardiomyopathy

et al. 2004

View full text Add to dashboard Cite

“…The rotational correlation times were similar, implying that the RD is fairly rigid, thus allowing force transmission from the CD (29). The mobility of the RD of SMM is much slower than that of skMM as implied by higher intensity at diagnostic L″, C′, and H″ positions, see Figure 4a,b.…”

Section: Rd Dynamics Of Different Isoforms: Smm Vs Skmmmentioning

confidence: 84%

“…InVSL has been previously found to be fully immobilized on a number of proteins, e.g., skeletal myosin S1 and ELC (27,28), RLC (29), troponin C and troponin I (41). To check the immobilization of InVSL on Cys-108 of gRLC we have cross-linked the InVSL-RLC to DITC-coated glass beads.…”

Section: Invsl As a Probe For Domain Motionmentioning

confidence: 99%

See 1 more Smart Citation

Regulatory and Catalytic Domain Dynamics of Smooth Muscle Myosin Filaments

Song

Salzameda

et al. 2006

Biochemistry

View full text Add to dashboard Cite

Domain dynamics of the chicken gizzard smooth muscle myosin catalytic domain (heavy chain Cys-717) and regulatory domain (regulatory light chain Cys-108) were determined in the absence of nucleotides using saturation-transfer electron paramagnetic resonance. In unphosphorylated synthetic filaments, the effective rotational correlation times, τ r , were 24 ± 6 μs and 441 ± 79 μs for the catalytic and regulatory domains, respectively. The corresponding amplitudes of motion were 42 ± 4° and 24 ± 9° as determined from steady-state phosphorescence anisotropy. These results suggest that the two domains have independent mobility due to a hinge between the two domains. Although a similar hinge was observed for skeletal myosin (Adhikari and Fajer (1997) Proc. Natl. Acad. Sci. U.S. A. 94, 9643-9647. Brown et al. (2001) Biochemistry 40,[8283][8284][8285][8286][8287][8288][8289][8290][8291], the latter displayed higher regulatory domain mobility, τ r = 40 ± 3 μs, suggesting a smooth muscle specific mechanism of constraining regulatory domain dynamics. In the myosin monomers the correlation times for both domains were the same (~4 μs) for both smooth and skeletal myosin, suggesting that the motional difference between the two isoforms in the filaments was not due to intrinsic variation of hinge stiffness. Heavy chain/regulatory light chain chimeras of smooth and skeletal myosin pinpointed the origin of the restriction to the heavy chain and established correlation between the regulatory domain dynamics with the ability of myosin to switch off but not to switch on the ATPase and the actin sliding velocity. Phosphorylation of smooth muscle myosin filaments caused a small increase in the amplitude of motion of the regulatory domain (from 24 ± 4° to 36 ± 7°) but did not significantly affect the rotational correlation time of the regulatory domain (441 to 408 μs) or the catalytic domain (24 to 17 μs). These data are not consistent with a stable interaction between the two catalytic domains in unphosphorylated smooth muscle myosin filaments in the absence of nucleotides. † This material is based upon work supported by the National Science Foundation under Grant No. 0346650, the AHA GIA 0455236B to P.G.F., and NIH AR40917 to C.R.C. and TCMRC 90103 to H.-C.L. L.S. is a recipient of American Heart Graduate Fellowship. *Author to whom correspondence should be addressed. Mailing address: Inst. Molecular Biophysics, Florida State University, Tallahassee, FL 32306. Tel: 850-645-1335. Fax: 850-644-1366. fajer@magnet.fsu.edu. ‡ Florida State University. § Tzu-Chi University. || These authors contributed equally. ⊥ University of Nevada School of Medicine. HHS Public Access Author Manuscript Author ManuscriptAuthor Manuscript Author ManuscriptMyosins are a superfamily of motor proteins that convert the chemical energy derived from ATP hydrolysis to mechanical energy by generating movement or force. Myosin II, the major protein from muscle, consists of two globular head domains and a coiled-coil tail or rod domain. At physiological...

show abstract

The Regulatory Domain of the Myosin Head Behaves as a Rigid Lever

Cited by 17 publications

References 52 publications

Response of Rigor Cross-bridges to Stretch Detected by Fluorescence Lifetime Imaging Microscopy of Myosin Essential Light Chain in Skeletal Muscle Fibers

Response of Rigor Cross-bridges to Stretch Detected by Fluorescence Lifetime Imaging Microscopy of Myosin Essential Light Chain in Skeletal Muscle Fibers

Myosin binding protein C: Structural abnormalities in familial hypertrophic cardiomyopathy

Regulatory and Catalytic Domain Dynamics of Smooth Muscle Myosin Filaments

Contact Info

Product

Resources

About