Casbene: An anti-fungal diterpene produced in cell-free extracts of Ricinus communis seedlings

Sitton, D.; West, Charles A.

doi:10.1016/0031-9422(75)83098-6

Cited by 68 publications

(21 citation statements)

References 18 publications

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“…This result is expected since the results of Table II Earlier work had demonstrated that casbene synthetase activity increased substantially after elicitation in comparison with the undetectable or very low values found in extracts of uninfected controls (7,28). The experiments summarized in Table I indicate that elicitation of casbene synthesis in 3-d-old castor bean seedlings results not only in an increase in casbene synthetase activity, but also in the activities of geranyl transferase and farnesyl transferase.…”

Section: Separation Of Organelles Inmentioning

confidence: 58%

“…Sitton and West (28) have proposed that casbene serves the castor bean plant as a phytoalexin based upon (a) the increased level of its production in the seedling after infection by Rhizopus stolonifer or other fungi and (b) its antibiotic properties. The radial growth of Aspergillus niger on agar plates was significantly inhibited by 10 to 20 tsg of casbene per ml.…”

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confidence: 99%

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Biosynthesis of the Macrocyclic Diterpene Casbene in Castor Bean (Ricinus communis L.) Seedlings

Dudley¹,

Dueber²,

West³

1986

Plant Physiol.

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ABSTRACICasbene is a macrocyclic diterpene hydrocarbon that is produced in young castor bean (Ricinus communis L.) seedlings after they are exposed to Rhizopus stolonifer or other fungi. The activities of enzymes that participate in casbene biosynthesis were measured in cell-free extracts of 67-hour castor bean seedlings (a) that had been exposed to R. stolonifer spores 18 hours prior to the preparation of extracts, and (b) that were maintained under aseptic conditions throughout. Activity for the conversion of mevalonate to isopentenyl pyrophosphate does not change significantly after infection. On the other hand, the activities of farnesyl pyrophosphate synthetase (geranyl transferase), geranylgeranyl pyrophosphate synthetase (farnesyl transferase), and casbene synthetase are all substantially greater in infected tissues in comparison with control seedlings maintained under sterile conditions. The subcellular localization of these enzymes of casbene biosynthesis was investigated in preparations of microsomes, mitochondria, glyoxysomes, and proplastids that were resolved by centrifugation in linear and step sucrose density gradients of homogenates of castor bean endosperm tissue from both infected and sterile castor bean seedlings. Isopentenyl pyrophosphate isomerase and geranyl transferase activities are associated with proplastids from both infected and sterile seedlings. Significant levels of farnesyl transferase and casbene synthetase are found only in association with the proplastids of infected tissues and not in the proplastids of sterile tissues. From these results, it appears that at least the last two steps of casbene biosynthesis, geranylgeranyl pyrophosphate synthetase and casbene synthetase, are induced during the process of infection, and that the enzymes responsible for the conversion of isopentenyl pyrophosphate to casbene are localized in proplastids.

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Section: Separation Of Organelles Inmentioning

confidence: 58%

mentioning

confidence: 99%

Biosynthesis of the Macrocyclic Diterpene Casbene in Castor Bean (Ricinus communis L.) Seedlings

Dudley¹,

Dueber²,

West³

1986

Plant Physiol.

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“…Casbene, a macrocyclic diterpene hydrocarbon with antifungal antibiotic properties, is produced in cell-free extracts of castor bean seedlings which have been exposed to spores of Rhizopus stolonifer or other fungi (20), to the extracellular endopolygalacturonase of R. stolonifer culture filtrates (12), or to pectic fragments released from pectic substances of the plant cell wall…”

Section: Abstracimentioning

confidence: 99%

“…One peak of farnesyl transferase activity (geranylgeranyl pyrophosphate synthetase) and two peaks of geranyl transferase activity (farnesyl pyrophosphate synthetases) from extracts of whole elicited seedlings were resolved by DEAE A-25 Sephadex sievorptive ion exchange chromatography. These results suggest that the pathway for geranylgeranyl pyrophosphate synthesis in elicited castor bean seedlings involves the successive actions of two enzymes-a geranyl transferase which utilizes dimethylallypyrophosphate and isopentenyl pyrophosphate as substrates and a farnesyl transferase which utilizes the farnesyl pyrophosphate produced in the first step and isopentenyl pyrophosphate as substrates.Casbene, a macrocyclic diterpene hydrocarbon with antifungal antibiotic properties, is produced in cell-free extracts of castor bean seedlings which have been exposed to spores of Rhizopus stolonifer or other fungi (20), to the extracellular endopolygalacturonase of R. stolonifer culture filtrates (12), or to pectic fragments released from pectic substances of the plant cell wall …”

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Biosynthesis of the Macrocyclic Diterpene Casbene in Castor Bean (Ricinus communis L.) Seedlings

Dudley¹,

Green²,

West³

1986

Plant Physiol.

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ABSTRACIFarnesyl transferase (farnesyl pyrophosphate: isopentenyl pyrophosphate farnesyl transferase; geranylgeranyl pyrophosphate synthetase) was purified at least 400-fold from extracts of castor bean (Ricinus communis L.) seedlings that were elicited by exposure for 10 h to Rhizopus stolonifer spores. The purified enzyme was free of isopentenyl pyrophosphate isomerase and phosphatase activities which interfere with prenyl transferase assays. The purified enzyme showed a broad optimum for farnesyl transfer between pH 8 and 9. The molecular weight of the enzyme was estimated to be 72,000 ± 3,000 from its behavior on a calibrated G-100 Sephadex molecular sieving column. Mg2" ion at 4 millimolar gave the greatest stimulation of activity; Mn2 ion gave a small stimulation at 0.5 millimolar, but was inhibitory at higher concentrations. Farnesyl pyrophosphate (Km = 0.5 micromolar) in combination with isopentenyl pyrophosphate (K,,, = 3.5 micromolar) was the most effective substrate for the production of geranylgeranyl pyrophosphate. Geranyl pyrophosphate (K. = 24 micromolar) could replace farnesyl pyrophosphate as the allylic pyrophosphate substrate, but dimethylallyl pyrophosphate was not utilized by the enzyme. One peak of farnesyl transferase activity (geranylgeranyl pyrophosphate synthetase) and two peaks of geranyl transferase activity (farnesyl pyrophosphate synthetases) from extracts of whole elicited seedlings were resolved by DEAE A-25 Sephadex sievorptive ion exchange chromatography. These results suggest that the pathway for geranylgeranyl pyrophosphate synthesis in elicited castor bean seedlings involves the successive actions of two enzymes-a geranyl transferase which utilizes dimethylallypyrophosphate and isopentenyl pyrophosphate as substrates and a farnesyl transferase which utilizes the farnesyl pyrophosphate produced in the first step and isopentenyl pyrophosphate as substrates.Casbene, a macrocyclic diterpene hydrocarbon with antifungal antibiotic properties, is produced in cell-free extracts of castor bean seedlings which have been exposed to spores of Rhizopus stolonifer or other fungi (20), to the extracellular endopolygalacturonase of R. stolonifer culture filtrates (12), or to pectic fragments released from pectic substances of the plant cell wall

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Phytoalexins: Enzymology and Molecular Biology

Dixon¹,

Dey²,

Lamb

1983

Advances in Enzymology - And Related Areas of Molecular Biology

220

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Casbene: An anti-fungal diterpene produced in cell-free extracts of Ricinus communis seedlings

Cited by 68 publications

References 18 publications

Biosynthesis of the Macrocyclic Diterpene Casbene in Castor Bean (Ricinus communis L.) Seedlings

Biosynthesis of the Macrocyclic Diterpene Casbene in Castor Bean (Ricinus communis L.) Seedlings

Biosynthesis of the Macrocyclic Diterpene Casbene in Castor Bean (Ricinus communis L.) Seedlings

Phytoalexins: Enzymology and Molecular Biology

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