Abstract
Rapid petiolar bending and leaf closing of Mimosa pudica L. occurs in response to mechanical, thermal, electrical, and chemical stimuli. We have reported that phosphorylation/dephosphorylation cycles at tyrosine residue play a role in this seismonastic movement. However, protein tyrosine phosphatase (PTP) in plants is less well-characterized than those in animals. In the present study, we have isolated and characterized cDNA clones (MpPTP1 and MpPTP2) encoding tyrosine phosphatase of Mimosa plant. For characterization, the biochemical properties of these clones, GST-fused MpPTPs were expressed in E. coli, and its phosphatase activity was measured. Both clones exhibited a tyrosine-specific phosphatase activity. Analysis of expression profiles of these clones reveals that MpPTP1 was specifically expressed in root. We further examined the effect of PTP-inhibitor, phenylarsine oxide (PAO), on development. Unusual root growth was observed by incubating seedlings in PAO-containing media. Thus, we consider that MpPTP1 affects the root development negatively in mimosa pudica.
