綠豆防禦素VrD1之抗蟲活性及其與鉀離子通道作用之分子機制探討
Date Issued
2005
Date
2005
Author(s)
薛宜青
DOI
zh-TW
Abstract
A variety of evolutionarily related defensin molecules is found in plants and animals. However, little is known about whether defensins are also involved in plant resistance to insect. A cDNA encoding a small cysteine-rich protein designated VrD1 (VrCRP) was isolated in the laboratory of Prof. Ching-San Chen, Academia Sinica, from the bruchid-resistant mungbean -- a well-known important food source in Asia and worldwide. VrD1 is apparently the first reported plant defensin exhibiting in vitro and in vivo insecticidal activity against C. chinensis. The molecular and structural basis of such unique insecticidal activity of VrD1 is not clear.
VrD1 has a four-disulfide linkage which connects the cysteine-stabilizing helix and the β–sheet, and can be categorized as a member of the γ-thionin family. From our structural analysis, VrD1 may use the three to four basic residues on one side of the molecule to perform the interaction with its membrane target, which is comprehended as potassium or chloride channel(s). And as further described in this thesis, our electrophysiological results with whole-cell recordings have demonstrated a very large inhibitory effect of VrD1 on the membrane potentials of SF-21 cells. Upon utilization of the channel agonists/antagonists, it is suggested that the insecticidal activity of VrD1 be very possibly related to the modulation or directly targeting at the potassium channels on Sf-21 plasma membranes. The exact channel type(s) is still under intensive investigations and will be the focused concerns in the near future.
Not only to provide the necessary information required for the studies of molecular mechanisms, our data should be also very helpful in the development of bioactive insecticides and in the related rational drug designs.
Subjects
綠豆防禦素
鉀離子通道
VrD1
cysteine-rich proteins
potassium channel
Type
other
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