Structural Study on K-Segment of Rice Dehydrin in Mimetic Membrane / 分析化学

ABSTRACT

Dehydrins are well associated with the abiotic stress tolerance of the plants, such as dehydration, salt stress and cold stress. They include a highly conserved lysine-rich motif called K-segment, which is believed to play a significant role in dehydrin function. The K-segment shows in vitro antibacterial activity against Gram-positive bacteria like its full-length dehydrin protein. In this study, the structures of the K-segment from rice dehydrin have been investigated by CD spectroscopy, NMR and molecular dynamic simulation. The results reveal that the K-segment is disordered in aqueous solution, but adopts helical structure in mimetic membrane environment, sodium dodecyl sulfate (SDS) micelles. The central region of K-segment forms an a-helix and exhibits amphipathic arrangement,where hydrophobic residues locate on one side and hydrophilic residues are on the other side. The amphipathic feature allows the helix region of the K-segment to insert into the SDS micelles, resulting in stable association with mimetic membrane. To realize the energy minimization,the hydrophobic side of the helix faces to the hydrophobic core of SDS micelles,and the hydrophilic side of the helix faces to the surface of micelles. The precise 3D structure and orientation information of the K-segment obtained in this work might provide new insights in understanding the structure-function relationship of dehydrins.