scholarly journals The effects of caldesmon on the ATPase activities of rabbit skeletal-muscle myosin

1986 ◽  
Vol 238 (2) ◽  
pp. 523-530 ◽  
Author(s):  
M S Lim ◽  
M P Walsh

We studied the effects of caldesmon, a major actin- and calmodulin-binding protein found in a variety of muscle and non-muscle tissues, on the various ATPase activities of skeletal-muscle myosin. Caldesmon inhibited the actin-activated myosin Mg2+-ATPase, and this inhibition was enhanced by tropomyosin. In the presence of the troponin complex and tropomyosin, caldesmon inhibited the Ca2+-dependent actomyosin Mg2+-ATPase; this inhibition could be partly overcome by Ca2+/calmodulin. Caldesmon, phosphorylated to the extent of approximately 4 mol of Pi/mol of caldesmon, inhibited the actin-activated myosin Mg2+-ATPase to the same extent as did non-phosphorylated caldesmon. Both inhibitions could be overcome by Ca2+/calmodulin. Caldesmon also inhibited the Mg2+-ATPase activity of skeletal-muscle myosin in the absence of actin; this inhibition also could be overcome by Ca2+/calmodulin. Caldesmon inhibited the Ca2+-ATPase activity of skeletal-muscle myosin in the presence or absence of actin, at both low (0.1 M-KCl) and high (0.3 M-KCl) ionic strength. Finally, caldesmon inhibited the skeletal-muscle myosin K+/EDTA-ATPase at 0.1 M-KCl, but not at 0.3 M-KCl. Addition of actin resulted in no inhibition of this ATPase by caldesmon at either 0.1 M- or 0.3 M-KCl. These observations suggest that caldesmon may function in the regulation of actin-myosin interactions in striated muscle and thereby modulate the contractile state of the muscle. The demonstration that caldesmon inhibits a variety of myosin ATPase activities in the absence of actin indicates a direct effect of caldesmon on myosin. The inhibition of the actin-activated Mg2+-ATPase activity of myosin (the physiological activity) may not be due therefore simply to the binding of caldesmon to the actin filament causing blockage of myosin-cross-bridge-actin interaction.

Dorothy M. Needham speaking. Since the pioneer work of Csapo and his colleagues, beginning about fifteen years ago, it has been realized that from uterine smooth muscle can be extracted a protein closely resembling skeletal-muscle actomyosin in its viscous behaviour, sedimentation rate and electrophoretic mobility. (See, for example, Csapo 1948, 1949, 1950, 1959; Csapo, Erdos, Naeslund & Snellman 1950; Naeslund & Snellman 1951). Later work, in which the properties of purified preparations of myosin, actin and actomyosin have been studied, bears out these earlier conclusions. Thus, for example, we have shown (Needham & Williams 1963 b ) that skeletal-muscle myosin will react normally with uterus actin to give the highly viscous actomyosin; and similarly uterus myosin with skeletal-muscle actin. In both types of experiment the results indicated that the two proteins associated together in about the same proportions as when both are derived from skeletal muscle. Uterus actomyosin may be fragmented by carefully controlled trypsin treatment giving light and heavy meromyosins which, so far as they have been studied, show similar properties to the meromyosins from skeletal-muscle actomyosin (Needham & Williams 1959; Cohen, Lowey & Kucera 1961). Smooth muscle, however, does contain very strikingly less actomyosin than striated muscle, only 6 to 10 mg/g wet wt as compared with about 70 mg/g wet wt in skeletal muscle (Needham & Williams 1963 a ).


2017 ◽  
Vol 39 (3) ◽  
pp. 309-319
Author(s):  
Vu Van Dung ◽  
Yoshitaka Umetsu ◽  
Shinya Ohki

In our previous study, functional ability and conformational stability had been examined for C-terminal deletion mutants of a 148-residue Ca2+-binding protein, chicken calmodulin (CaM). In that study, we had reported that a mutant named CCMΔ5, missing five residues at the C-terminus, activates CaM-target as much as full-length CaM does. This finding is intriguing because CCMΔ5 lacks the key residues, Met144 and Met145, for the target activation. To uncover why CCMΔ5 displays proper function, here we report the three-dimensional structure of CCMΔ5 bound to the peptide derived from skeletal muscle myosin light-chain kinase (skMLCK). The structure determination was achieved using multidimensional nuclear magnetic resonance (NMR) spectroscopy. The complex structure of CCM∆5-skMLCK was compared to that of wild CaM-skMLCK. The results showed that the orientation of helix-1 and helix-5 in CCM∆5 differs from those in wild CaM. Moreover, distinctive hydrophobic interaction manner was found in the binding between CCM∆5 and peptide; Phe141, Ala128, Met109, Leu105 and Phe92 of CCM∆5 contribute to the interaction with Trp4 of the skMLCK peptide.   Abbreviations: CaM, calmodulin; CCMΔX, a deletion mutant of CaM that lacks X C-terminal residues; NMR, Nuclear magnetic resonance; PDB, Protein date bank; skMLCK, skeletal muscle myosin light-chain kinase; TOF-MS, Time-of-flight mass spectrometry; RMSD, root mean square deviation; SDS-PAGE, Sodium dodecyl sulfate polyacrylamide gel electrophoresis Citation: Vu Van Dung, Umetsu Y., Ohki S., 2017. Three-dimensional structure of the complex between calmodulin mutant lacking the c-terminal five residues and the calmodulin-binding peptide derived from skeletal muscle myosin light-chain kinase. Tap chi Sinh hoc, 39(3): 309-319. DOI: 10.15625/0866-7160/v39n3.10111. *Corresponding author: [email protected] Received 19 June 2017, accepted 20 August 2017 


1985 ◽  
Vol 82 (10) ◽  
pp. 3187-3191 ◽  
Author(s):  
D. K. Blumenthal ◽  
K. Takio ◽  
A. M. Edelman ◽  
H. Charbonneau ◽  
K. Titani ◽  
...  

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