Identification and Transformation of Campestanol in Cultured Cells of Phaseolus vulgaris

J Korean Soc Appl Biol Chem

2012

We recently demonstrated that non-plant cells, yeast WAT21, produce a steroidal plant hormone, castasterone. To understand how castasterone is generated in WAT21 cells, deuteriumlabeled (26, 28-2 H 6 ) 6-deoxoteasterone, 6-deoxotyphasterol and 6deoxocastasterone were fed to WAT21 cells, and their metabolites were analyzed by gas chromatography-mass spectrometry. When [ 2 H 6 ]-6-deoxoteasterone was fed, [ 2 H 6 ]-6-deoxo-3-dehydroteasterone and [ 2 H 6 ]-6-deoxotyphasterol were identified as metabolites. When [ 2 H 6 ]-6-deoxotyphasterol was used, [ 2 H 6 ]-6-deoxoteasterone and [ 2 H 6 ]-6-deoxo-3-dehydroteasterone and [ 2 H 6 ]-6-deoxocastasterone were detected. When [ 2 H 6 ]-6-deoxocastasterone was added, [ 2 H 6 ]castasterone was identified. Taken together, a biosynthetic sequence, 6-deoxoteasterone↔6-deoxo-3-dehydroteasterone↔6-deoxotyphasterol →6-deoxocastasterone→castasterone seems to function to produce brassinosteroids in WAT21 cells. Coupled with the presence of a biosynthetic sequence, teasterone→3-dehydroteasterone↔ typhasterol →castasterone, this suggests that brassinosteroids in WAT21 cells were biosynthesized via the same kind of pathways established in plants. This study provides a clue for possible mass-production of brassinosteroids in non-plant cells, yeast WAT21 for commercial use in agriculture.

Biotransformation of 6-deoxo type brassinosteroids in yeast (Saccharomyces cerevisiae) WAT21 cells

Son

J Korean Soc Appl Biol Chem

2012

Biosynthesis of a cholesterol-derived brassinosteroid, 28-norcastasterone, in Arabidopsis thaliana

Joo

Journal of Experimental Botany

Son

et al. 2011

A metabolic study revealed that 28-norcastasterone in Arabidopsis is synthesized from cholesterol via the late C-6 oxidation pathway. On the other hand, the early C-6 oxidation pathway was found to be interrupted because cholestanol is converted to 6-oxocholestanol, but further metabolism to 28-norcathasterone was not observed. The 6-oxoBRs were found to have been produced from the respective 6-deoxoBRs administered to the enzyme solution, thus indicating that these 6-oxoBRs are supplied from the late C-6 oxidation pathway. Heterologously expressed CYP85A1 and CYP85A2 in yeast catalysed this C-6 oxidation, with CYP85A2 being much more efficient than CYP85A1. Abnormal growth of det2 and dwf4 was restored via the application of 28-norcastasterone and closer precursors. Furthermore, det2 and dwf4 could not convert cholesterol to cholestanol and cholestanol to 6-deoxo-28-norcathasterone, respectively. It is, therefore, most likely that the same enzyme system is operant in the synthesis of both 28-norcastasterone and castasterone. In the presence of S-adenosyl-L-methionine, the cell-free enzyme extract catalysed the C-24 methylation of 28-norcastasterone to castasterone, although the conversion rates of 28-norteasterone to teasterone and 28-nortyphasterol to typhasterol were much lower; this suggests that 28-norcastasterone is the primary precursor for the generation of C28-BRs from C27-BRs.

Function and molecular regulation of DWARF1 as a C-24 reductase in brassinosteroid biosynthesis in Arabidopsis

Youn

Journal of Experimental Botany

Joo

et al. 2018