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

1. Myosin and its subfragment-1 (S1) From carp acclimated to 10 degrees C showed higher actin-activated Mg2+-ATPase activity and lower thermostability than their counterparts from carp acclimated to 30 degrees C. Accordingly, filament velocity for the 10 degrees C-acclimated carp myosin was higher at any measuring temperatures from 3 to 23 degrees C than that for the 30 degrees C-acclimated carp myosin. 2. Three types of cDNA clones encoding myosin heavy chains were isolated from thermally acclimated carp. The 10 and 30 degrees C types were predominating in carp acclimated to 10 and 30 degrees C, respectively, whereas the intermediate type was found as a minor component in the 10 degrees C-acclimated carp with an intermediate feature in both DNA nucleotide and deduced amino acid sequences between those of the 10 and 30 degrees C types. 3. The three types of myosin rod all showed a typical coiled-coil structure of alpha-helices. DSC scans demonstrated that myosin rod prepared from carp acclimated to 10 degrees C had a lower thermostability than that from carp acclimated to 30 degrees C. showing that low thermostability in cold-acclimated carp myosin prevails over the entire molecule. 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 degrees C- than 10 degrees C-acclimated (3.10) carp. (C) 1998 Elsevier Science Ltd. All rights reserved.