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Screening marine fungi for inhibitors of the C4 plant enzyme pyruvate phosphate dikinase: unguinol as a potential novel herbicide candidate.

ABSTRACT: A total of 2,245 extracts, derived from 449 marine fungi cultivated in five types of media, were screened against the C(4) plant enzyme pyruvate phosphate dikinase (PPDK), a potential herbicide target. Extracts from several fungal isolates selectively inhibited PPDK. Bioassay-guided fractionation of one isolate led to the isolation of the known compound unguinol, which inhibited PPDK with a 50% inhibitory concentration of 42.3 +/- 0.8 muM. Further kinetic analysis revealed that unguinol was a mixed noncompetitive inhibitor of PPDK with respect to the substrates pyruvate and ATP and an uncompetitive inhibitor of PPDK with respect to phosphate. Unguinol had deleterious effects on a model C(4) plant but no effect on a model C(3) plant. These results indicate that unguinol inhibits PPDK via a novel mechanism of action which also translates to an herbicidal effect on whole plants.

SUBMITTER: Motti CA

PROVIDER: S-EPMC1828816 | biostudies-literature | 2007 Mar

REPOSITORIES: biostudies-literature

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Screening marine fungi for inhibitors of the C4 plant enzyme pyruvate phosphate dikinase: unguinol as a potential novel herbicide candidate.

Motti Cherie A CA Bourne David G DG Burnell James N JN Doyle Jason R JR Haines Dianne S DS Liptrot Catherine H CH Llewellyn Lyndon E LE Ludke Shilo S Muirhead Andrew A Tapiolas Dianne M DM

Applied and environmental microbiology 20070112 6

A total of 2,245 extracts, derived from 449 marine fungi cultivated in five types of media, were screened against the C(4) plant enzyme pyruvate phosphate dikinase (PPDK), a potential herbicide target. Extracts from several fungal isolates selectively inhibited PPDK. Bioassay-guided fractionation of one isolate led to the isolation of the known compound unguinol, which inhibited PPDK with a 50% inhibitory concentration of 42.3 +/- 0.8 muM. Further kinetic analysis revealed that unguinol was a mi ...[more]

PMID: 17220253

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Project description:1. The activity of pyruvate,P(i) dikinase in leaves of maize and Amaranthus palmeri rapidly falls on transferring illuminated plants to darkness. Illumination of dark-treated plants results in an immediate rapid increase in activity of the enzyme, the final activity reached being dependent on the intensity of the incident light. 2. Activation of the enzyme in extracts of dark-treated maize leaves after gel filtration on Sephadex G-25 requires a thiol and P(i). The P(i) requirement for activation can be replaced by arsenate. Activation of the enzyme is inhibited by AMP and GMP and possibly also by ADP and ATP. Activation of the enzyme after gel filtration on Sephadex G-200 also requires a heat-labile component that is excluded by Sephadex G-25. 3. The active enzyme isolated from illuminated leaves is inactivated by ADP in the presence of a thiol, the rate of inactivation being very much faster in air than in an oxygen-free atmosphere. Reactivation of the ADP-inactivated enzyme requires a thiol, P(i) and a component excluded by Sephadex G-25 but considerably retarded by Sephadex G-200. 4. The active enzyme is rapidly and irreversibly inactivated in the absence of a thiol. Inactivation is accelerated by both sodium diethyldithiocarbamate and tetraethylthiuram disulphide, and the enzyme inactivated by these reagents is completely reactivated by incubation with dithiothreitol. This reactivation does not require P(i). The inactive enzyme from dark-treated leaves is stabilized by diethyldithiocarbamate and can be partially activated by dithiothreitol alone; complete reactivation requires both dithiothreitol and P(i). 5. The enzyme activity is markedly inhibited by the thiol reagents p-chloromercuribenzoate, gamma-(p-arsenophenyl)-n-butyrate and an equimolar mixture of arsenite and 2,3-dimercaptopropan-1-ol. 6. The processes of activation and inactivation observed in vitro are discussed in relation to the regulation of pyruvate,P(i) dikinase activity in the leaf.

Dataset Information

Screening marine fungi for inhibitors of the C4 plant enzyme pyruvate phosphate dikinase: unguinol as a potential novel herbicide candidate.

Publications

Screening marine fungi for inhibitors of the C4 plant enzyme pyruvate phosphate dikinase: unguinol as a potential novel herbicide candidate.

Similar Datasets

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