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

Title
Biosynthesis of a cholesterol-derived brassinosteroid, 28-norcastasterone, in Arabidopsis thaliana
Author
김태욱
Keywords
Arabidopsis thaliana; brassinosteroids; C-27-BRs biosynthesis; 28-norcastasterone
Issue Date
2012-03
Publisher
Oxford Univ Press
Citation
Journal of Experimental Botany, 2012, 63(5), P.1823-1833
Abstract
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 C-28-BRs from C-27-BRs.
URI
https://academic.oup.com/jxb/article/63/5/1823/525127http://repository.hanyang.ac.kr/handle/20.500.11754/69494
ISSN
0022-0957
DOI
10.1093/jxb/err354
Appears in Collections:
COLLEGE OF NATURAL SCIENCES[S](자연과학대학) > LIFE SCIENCE(생명과학과) > Articles
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