Microbial Hydroxylation of 24-Epicastasterone by the Fungus<i>Cochliobolus lunatus</i>

Voigt, B.; Porzel, Andrea; Undisz, Katrin; Hörhold‐Schubert, Cläre; Adam, Günter

doi:10.1080/10575639308043849

Cited by 6 publications

(4 citation statements)

References 13 publications

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“…Diglycosidation of exogenous 24-epiteasterone occurred in cell cultures of tomato, Lycopersicon esculentum (60), and in the same system, hydroxylation at the 25-and 26-positions of 24-epibrassinolide required two separate hydroxylases, with only the 25-hydroxylase sensitive to cytochrome P450 inhibitors (127). How many of these transformations occur in vivo as part of normal biosynthesis and turnover of BRs remains to be seen, but the possibility of very low levels of even more active members of the family, like those produced by fungal metabolism (48,117,118) is tantalizing.…”

Section: Conjugation and Metabolismmentioning

confidence: 99%

BRASSINOSTEROIDS: Essential Regulators of Plant Growth and Development

Clouse

Sasse

1998

Annu. Rev. Plant. Physiol. Plant. Mol. Biol.

1,253

776

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Brassinosteroids (BRs) are growth-promoting natural products found at low levels in pollen, seeds, and young vegetative tissues throughout the plant kingdom. Detailed studies of BR biosynthesis and metabolism, coupled with the recent identification of BR-insensitive and BR-deficient mutants, has greatly expanded our view of steroids as signals controlling plant growth and development. This review examines the microchemical and molecular genetic analyses that have provided convincing evidence for an essential role of BRs in diverse developmental programs, including cell expansion, vascular differentiation, etiolation, and reproductive development. Recent advances relevant to the molecular mechanisms of BR-regulated gene expression and BR signal transduction are also discussed.

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Section: Conjugation and Metabolismmentioning

confidence: 99%

BRASSINOSTEROIDS: Essential Regulators of Plant Growth and Development

Clouse

Sasse

1998

Annu. Rev. Plant. Physiol. Plant. Mol. Biol.

1,253

776

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“…On the other hand, the fungus Cochliobolus lunatus transformed 24-epicastasterone (14) to the corresponding 15β-hydroxylated compound 138 (Voigt et al, 1993b;figure 18).…”

Section: Biosynthesis and Metabolism Of Brassinosteroidsmentioning

confidence: 99%

Brassinosteroid phytohormones: structure, bioactivity and applications

Zullo

Adam²

2002

Braz. J. Plant Physiol.

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113

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“…We examined the zymomycetous pheromone trisporic acid[27] for competition for plasma membrane progesterone receptors of R. nigricans but it did not displace radiolabeled progesterone from membrane receptors (results not shown). The plant hormone brassinosteroid 24‐epicastasterone, which is converted into the hydroxy‐derivative by the fungus C. lunatus [28], was also tested, but no affinity for R. nigricans membrane progesterone receptors was detected (data not shown). Thus, progesterone appears to be the most appropriate candidate for the in vivo ligand of membrane‐bound receptors in R. nigricans .…”

Section: Resultsmentioning

confidence: 99%

Membrane-bound progesterone receptors coupled to G proteins in the fungusRhizopus nigricans

Lenasi

Bavec

Zorko

2002

FEMS Microbiology Letters

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Steroid binding sites with high affinity for progesterone (Kd=40+/-14 nM determined by binding, and Kd=71+/-22 nM determined by displacement studies) and lower affinity for 21-hydroxyprogesterone and for testosterone, but no affinity for estradiol-17beta, onapristone and alpha-naphthoflavone were detected in the enriched plasma membrane fraction of the fungus Rhizopus nigricans. The amount of steroid binding sites is in accordance with the value of B(max)=744+/-151 fmol (mg protein)(-1). In the membrane fraction, progesterone induced about 30% activation of G proteins over basal level, as determined by GTPase activity (EC50=32+/-8 nM) and by the guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS) binding rate (EC50=61+/-21 nM). The affinity of receptors for progesterone was substantially decreased in the presence of GTPgammaS and of cholera toxin. Our results suggest the existence of progesterone receptors in the membrane of Rhizopus nigricans and their coupling to G proteins.

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Microbial Hydroxylation of 24-Epicastasterone by the FungusCochliobolus lunatus

Cited by 6 publications

References 13 publications

BRASSINOSTEROIDS: Essential Regulators of Plant Growth and Development

BRASSINOSTEROIDS: Essential Regulators of Plant Growth and Development

Brassinosteroid phytohormones: structure, bioactivity and applications

Membrane-bound progesterone receptors coupled to G proteins in the fungusRhizopus nigricans

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