Carp expresses fast skeletal myosin isoforms with altered motor functions and structural stabilities to compensate for changes in environmental temperature

Abstract 1. 1. Myosin and its subfragment-1 (Sl) from carp acclimated to 10°C showed higher actin-activated Mg 2+ -ATPase activity and lower thermostability than their counterparts from carp acclimated to 30°C. Accordingly, filament velocity for the 10°C-acclimated carp myosin was higher at any measuring temperatures from 3 to 23°C than that for the 30°C-acclimated carp myosin. 2. 2. Three types of cDNA clones encoding myosin heavy chains were isolated from thermally acclimated carp. The 10 and 30°C types were predominating in carp acclimated to 10 and 30°C, respectively, whereas the intermediate type was found as a minor component in the 10°C-acclimated carp with an intermediate feature in both DNA nucleotide and deduced amino acid sequences between those of the 10 and 30°C types. 3. 3. The three types of myosin rod all showed a typical coiled-coil structure of α-helices. DSC scans demonstrated that myosin rod prepared from carp acclimated to 10°C had a lower thermostability than that from carp acclimated to 30°C, showing that low thermostability in cold-acclimated carp myosin prevails over the entire molecule. 4. 4. cDNA clones encoding myosin alkali light chains were isolated from thermally acclimated carp. Northern blot analysis showed that the ratios of LC3 LC1 mRNAs were significantly higher (3.92) in the 30°C- than 10°C-acclimated (3.10) carp.