Isolation of myosin XI genes from the Closterium peracerosum-strigosum-littorale complex and analysis of their expression during sexual reproduction.

Myosins comprise a large superfamily of molecular motors that generate mechanical force in ATP-dependent interactions with actin filaments. On the basis of their conserved motor domain sequences, myosins can be divided into at least 17 classes, 3 of which (VIII, XI, XIII) are found in plants. Although full sequences of myosins are available from several species of green plants, little is known about the functions of these proteins. Additionally, sequence information for algal myosin is incomplete, and little attention has been given to the molecular evolution of myosin from green plants. In the present study, the Closterium peracerosum-strigosum-littorale complex was used as a model system for investigating a unicellular basal charophycean alga. This organism has been well studied with respect to sexual reproduction between its two mating types. Three types of partial sequences belonging to class XI myosins were obtained using degenerate primers designed to amplify motor domain sequences. Real-time polymerase chain reaction analysis of the respective myosin genes during various stages of the algal life cycle showed that one of the genes was more highly expressed during sexual reproduction, and that expression was cell-cycle-dependent in vegetatively grown cells.