Reconstitution of ventricular myosin with atrial light chains 1 improves its functional properties.
Atrial light chain 1 (ALC-1) is expressed in embryonic and hypertrophied human ventricles but not in normal adult human ventricles. We investigated the effects of recombinant human atrial light chains (hALC-1) on the structure and enzymatic activity of synthetic filaments of ventricular myosin. The endogenous ventricular myosin light chain 1 (VLC-1) was partially replaced by recombinant hALC-1 yielding hALC-1 levels of 12%, 24% and 42%. This reconstitution of ventricular myosin with hALC-1 did not change the length of synthetic myosin filaments but led to more rounded myosin heads in comparison with those of control filaments. Actin-activated ATPase activity of myosin, a parameter of functional activity of molecular motor, amounted to 79.5 nmol P(i)/mg per min in control myosin filaments. Reconstitution with hALC-1 caused a profound increase of the actin-activated myosin ATPase activity in a dose dependent manner, for example, synthetic myosin filaments formed with 12%, 24% and 42% hALC-1 reconstituted myosin revealed the actin-activated ATPase activity increased by 18%, 26% and 36%, respectively, as compared to control. These results strongly suggest that in vivo expression of ALC-1 enhances ventricular myosin function, thereby contributing to cardiac compensation.
Khalina
Yana N
YN
Institute of Theoretical and Experimental Biophysics RAS, Laboratory of Structure and Function of Muscle Proteins, Pushchino, Russia.
Bartsch
Holger
H
Petzhold
Daria
D
Haase
Hannelore
H
Podlubnaya
Zoya A
ZA
Shpagina
Mila D
MD
Morano
Ingo
I
D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D008854:Microscopy, Electron; D018994:Myosin Light Chains / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D009218:Myosins / Q000378:metabolism
D018994:Myosin Light Chains; C491915:hALC-1 protein, human; D009218:Myosins