49. The biosynthesis of the gibberellins. Part I. (—)-Kaurene as a precursor of gibberellic acid

Cross, B. E.; Galt, R. H. B.; Hanson, James R.

doi:10.1039/jr9640000295

Cited by 90 publications

(18 citation statements)

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“…Earlier studies, which were designed to elucidate the biosynthetic pathway leading to formation of kaurene, were performed with preparations which had a high capacity for kaurene production (1,5,15,17,21). Attempts to correlate the rate of pro- In 'Alaska' pea shoots, a parallel increase in GA production and rate of kaurene synthesis was observed (7), and in developing pea seeds, GA production lags slightly in the capacity for kaurene synthesis (2).…”

Section: Discussionmentioning

confidence: 99%

Comparison between Biosynthesis of ent-Kaurene in Germinating Tomato Seeds and Cell Suspension Cultures of Tomato and Tobacco

Yafin¹,

Shechter²

1975

Plant Physiol.

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Biosynthesis of ent-kaurene was investigated in extracts of cell suspension cultures derived from tobacco callus (Nicotiana tabacum L.), tomato callus (Solanum lycopersicum L.), and in germinating tomato seeds. Incubation of extracts derived from the two cell cultures with either isopentenyl pyrophosphate-'4C or with 14C-labeled mevalonate, followed by alkaline phosphatase hydrolysis, resulted in the formation of trans-geranylgeraniol-14C and trans-farnesol-14C. The corresponding pyrophosphates of trans-geranylgeraniol-'4C and trans-farnesol-_4C were also detected. No detectable amount of ent-kaurene-14C was produced by these enzymatic preparations when trans-geranylgeranyl-

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Section: Discussionmentioning

confidence: 99%

Comparison between Biosynthesis of ent-Kaurene in Germinating Tomato Seeds and Cell Suspension Cultures of Tomato and Tobacco

Yafin¹,

Shechter²

1975

Plant Physiol.

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“…Substantial progress toward the developnment of cell-free systems from immature seeds capable of GA biosynthesis from mevalonic acid (MVA) first was made when Graebe et al (9) reported on the biosynthesis of (-)-kaurene, a known intermediate in GA biosynthesis in Fusariunt monilifornte (5,9) and presumably also in highler plants, fromii MVA in cell-free extracts of Echinocystis macrocarpa Greene endosperm-nucellus. Subsequently, Robinson and West (18) (Fig.…”

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Apparent Changes in Rate of Kaurene Biosynthesis During the Development of Pea Seeds

Coolbaugh

Moore²

1969

Plant Physiol.

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“…The diterpene hydrocarbon ent-kaurene3, an intermediate in the pathway for the biosynthesis of gibberellins (6,15,17,26), is synthesized from the acyclic precursor geranylgeranyl-PP in a two ' step reaction catalyzed by kaurene synthetase (Fig. 1).…”

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Properties of Kaurene Synthetase from Marah macrocarpus Endosperm: Evidence for the Participation of Separate but Interacting Enzymes

Duncan¹,

West²

1981

Plant Physiol.

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Ent-kaurene is synthesized from geranylgeranyl pyrophosphate in a two step sequence catalyzed by kaurene synthetase; the first step (A activity) involves the conversion of geranylgeranyl pyrophosphate into the intermediate ent-trans labda-8(17), 13-dien-15-yl pyrophosphate (copalyl pyrophosphate) which is further cyclized to ent-kaurene in the second step (B activity). The step reaction catalyzed by kaurene synthetase (Fig. 1). In the first step (A activity) the intermediate copalyl-PP is synthesized from geranylgeranyl-PP (16,22). In the second stage of cyclization (B activity) copalyl-PP is converted to kaurene. Overall conversion of geranylgeranyl-PP into kaurene is referred to as AB activity.Because geranylgeranyl-PP is a branch point metabolite and serves as a precursor of carotenoids (2, 3, 21), the phytyl chain of Chl and other pigments (25), and other diterpenes as well as kaurene (20), it is likely that kaurene synthetase activity is subject to regulation based on the organism's need for kaurene at a given time (17). However, the in vivo regulation of the activity is not well understood. The presence of B activity in some mature tissues in the absence of detectable A activity (23,24,27) may reflect some aspect of regulation, although the basis for this has not been established.Overall AB activity can be detected in many immature plant tissues (4,11,13,14,19,20,23,27). It has not been established previously whether one enzyme catalyzes the overall reaction or if two separate enzymes are required, one for the A step and another for the B step. Preparations active in the catalysis of B but not AB activity have been obtained from plant sources that possess overall AB activity (23); however, all previous attempts to isolate an A enzyme free of B activity have been unsuccessful (8,11,23). An enzyme that converts geranylgeranyl-PP into kaurene has been purified 170-fold from mycelia of the gibberellin-producing fungus, Fusarium moniliforme (8). Throughout this purification a constant ratio of A to B activity was observed. It was not possible to dissociate the complex of about 460,000 daltons and retain either A or B activity. Kaurene synthetase preparations from cell-free extracts ofRicinus communis seedlings were resolved by DEAE Sephadex A-25 chromatography into two regions with B activity and one broad region with AB activity (23). Partial purification of kaurene synthetase from cell-free preparations of the endosperm of immature Marah macrocarpus seeds did not result in resolution of the A and B catalytic activities; however, the ratio of the two activities did not remain constant throughout purification (1 1).The present study was carried out to clarify further the relationship between the A and B activities of kaurene synthetase from a higher plant source because of its possible regulatory significance in gibberellin biosynthesis. Evidence will be presented which indicates that the synthesis of kaurene from geranylgeranyl-PP in endosperm tissue of M. macrocarpus is catalyzed by two separate...

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49. The biosynthesis of the gibberellins. Part I. (—)-Kaurene as a precursor of gibberellic acid

Cited by 90 publications

References 0 publications

Comparison between Biosynthesis of ent-Kaurene in Germinating Tomato Seeds and Cell Suspension Cultures of Tomato and Tobacco

Comparison between Biosynthesis of ent-Kaurene in Germinating Tomato Seeds and Cell Suspension Cultures of Tomato and Tobacco

Apparent Changes in Rate of Kaurene Biosynthesis During the Development of Pea Seeds

Properties of Kaurene Synthetase from Marah macrocarpus Endosperm: Evidence for the Participation of Separate but Interacting Enzymes

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