Abstract
Legume plants open their leaves early in the morning and close them in the evening. This phenomenon is called nyctinasty, which is controlled by circadian clock regulating the balance of concentrations between two endogenous bioactive substances, leaf-opening factor (LOF) and leaf-closing factor (LCF). Recent studies of Prof. M. Ueda et. al., (Tohoku University) identified a candidate for LOF binding protein in Cassia plant. Identified fragment sequences of the protein showed similarity to methionine synthase (MS). Thus, to examine whether MS is able to bind to LOF, how this binding affects MS activity, and whether MS plays the same role in other plants, we isolated cDNA clone of MS from Cassia obtusifolia. An anti-MS antibody generated against recombinant MS was used to examine the tissue distribution of MS. As a result, bacterially expressed recombinant proteins exhibited MS activity and were bound to LOF, though the activity was not changed by their binding. These data showed that MS appears to be a LOF receptor in vivo, though the role was still uncertain.
