Applied and Environmental Microbiology (2012) 78, 3816-3823
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Phospholipase A2 inhibitors synthesized by two entomopathogenic bacteria, Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata
Applied and Environmental Microbiology 78 (11), 3816-3823
Abstract: The entomopathogenic bacteria Xenorhabdus nematophila and Photorhabdus temperata subsp. temperata suppress insect immune responses by inhibiting the catalytic activity of phospholipase A2 (PLA2), which results in preventing biosynthesis of immune-mediating eicosanoids. This study identified PLA2 inhibitors derived from culture broths of these two bacteria. Both X. nematophila and P. temperata subsp. temperata culture broths possessed significant PLA2-inhibitory activities. Fractionation of these bacterial metabolites in the culture broths using organic solvent and subsequent chromatography purified seven potent PLA2 inhibitors, three of which (benzylideneacetone [BZA], proline-tyrosine [PY], and acetylated phenylalanine-glycine-valine [FGV]) were reported in a previous study. Four other compounds (indole, oxindole, cis-cyclo-PY, and p-hydroxyphenyl propionic acid) were identified and shown to significantly inhibit PLA2. X. nematophila culture broth contained these seven compounds, while P. temperata subsp. temperata culture broth contained three compounds (BZA, acetylated FGV, and cis-cyclo-PY). BZA was detected in the largest amount among these PLA2 compounds in both bacterial culture broths. All seven bacterial metabolites also showed significant inhibitory activities against immune responses, such as phenoloxidase activity and hemocytic nodulation; BZA was the most potent. Finally, this study characterized these seven compounds for their insecticidal activities against the diamondback moth, Plutella xylostella. Even though these compounds showed relatively low toxicities to larvae, they significantly enhanced the pathogenicity of Bacillus thuringiensis. This study reports bacterial-origin PLA2 inhibitors, which would be applicable for developing novel insecticides.
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Database assignments for author(s): Yong Gyun Kim
Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
molecular biology - genes
Pest and/or beneficial records:
|Bacillus thuringiensis (entomopathogen)||Plutella xylostella|
|Steinernema carpocapsae/Xenorhabdus nematophila (entomopathogen)||Plutella xylostella|
|Heterorhabditis megidis/Photorhabdus temperata (entomopathogen)||Plutella xylostella|