PMID- 9401120
OWN - NLM
STAT- MEDLINE
DCOM- 19980114
LR  - 20240109
IS  - 1040-4651 (Print)
IS  - 1532-298X (Electronic)
IS  - 1040-4651 (Linking)
VI  - 9
IP  - 11
DP  - 1997 Nov
TI  - The Arabidopsis deetiolated2 mutant is blocked early in brassinosteroid 
      biosynthesis.
PG  - 1951-62
AB  - The Arabidopsis DEETIOLATED2 (DET2) gene has been cloned and shown to encode a 
      protein that shares significant sequence identity with mammalian steroid 5 
      alpha-reductases. Loss of DET2 function causes many defects in Arabidopsis 
      development that can be rescued by the application of brassinolide; therefore, we 
      propose that DET2 encodes a reductase that acts at the first step of the proposed 
      biosynthetic pathway--in the conversion of campesterol to campestanol. Here, we 
      used biochemical measurements and biological assays to determine the precise 
      biochemical defect in det2 mutants. We show that DET2 actually acts at the second 
      step in brassinolide biosynthesis in the 5 alpha-reduction of 
      (24R)-24-methylcholest-4-en-3-one, which is further modified to form campestanol. 
      In feeding experiments using 2H6-labeled campesterol, no significant level of 
      2H6-labeled campestanol was detected in det2, whereas the wild type accumulated 
      substantial levels. Using gas chromatography-selected ion monitoring analysis, we 
      show that several presumed null alleles of det2 accumulated only 8 to 15% of the 
      wild-type levels of campestanol. Moreover, in det2 mutants, the endogenous levels 
      of (24R)-24-methylcholest-4-en-3-one increased by threefold, whereas the levels 
      of all other measured brassinosteroids accumulated to < 10% of wild-type levels. 
      Exogenously applied biosynthetic intermediates of brassinolide were found to 
      rescue both the dark- and light-grown defects of det2 mutants. Together, these 
      results refine the original proposed pathway for brassinolide and indicate that 
      mutations in DET2 block the second step in brassinosteroid biosynthesis. These 
      results reinforce the utility of combining genetic and biochemical analyses to 
      studies of biosynthetic pathways and strengthen the argument that 
      brassinosteroids play an essential role in Arabidopsis development.
FAU - Fujioka, S
AU  - Fujioka S
AD  - Institute of Physical and Chemical Research (RIKEN), Saitama, Japan.
FAU - Li, J
AU  - Li J
FAU - Choi, Y H
AU  - Choi YH
FAU - Seto, H
AU  - Seto H
FAU - Takatsuto, S
AU  - Takatsuto S
FAU - Noguchi, T
AU  - Noguchi T
FAU - Watanabe, T
AU  - Watanabe T
FAU - Kuriyama, H
AU  - Kuriyama H
FAU - Yokota, T
AU  - Yokota T
FAU - Chory, J
AU  - Chory J
FAU - Sakurai, A
AU  - Sakurai A
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, Non-P.H.S.
PL  - England
TA  - Plant Cell
JT  - The Plant cell
JID - 9208688
RN  - 0 (Arabidopsis Proteins)
RN  - 0 (Brassinosteroids)
RN  - 0 (Cholestanols)
RN  - 0 (DET2 protein, Arabidopsis)
RN  - 0 (Phytosterols)
RN  - 0 (Plant Proteins)
RN  - 0 (Steroids)
RN  - 0 (Steroids, Heterocyclic)
RN  - 5L5O665639 (campesterol)
RN  - 97C5T2UQ7J (Cholesterol)
RN  - AR09D82C7G (Deuterium)
RN  - EC 1.3.99.5 (3-Oxo-5-alpha-Steroid 4-Dehydrogenase)
RN  - Y9IQ1L53OX (brassinolide)
SB  - IM
MH  - 3-Oxo-5-alpha-Steroid 4-Dehydrogenase/*genetics
MH  - Arabidopsis/genetics/*metabolism
MH  - *Arabidopsis Proteins
MH  - Brassinosteroids
MH  - Cholestanols/metabolism
MH  - Cholesterol/analogs & derivatives/metabolism
MH  - Deuterium
MH  - *Mutation
MH  - Phenotype
MH  - *Phytosterols
MH  - Plant Proteins/*genetics
MH  - Steroids/*biosynthesis
MH  - Steroids, Heterocyclic/metabolism
PMC - PMC157049
EDAT- 1997/12/24 00:00
MHDA- 1997/12/24 00:01
PMCR- 1998/11/01
CRDT- 1997/12/24 00:00
PHST- 1997/12/24 00:00 [pubmed]
PHST- 1997/12/24 00:01 [medline]
PHST- 1997/12/24 00:00 [entrez]
PHST- 1998/11/01 00:00 [pmc-release]
AID - 9/11/1951 [pii]
AID - 10.1105/tpc.9.11.1951 [doi]
PST - ppublish
SO  - Plant Cell. 1997 Nov;9(11):1951-62. doi: 10.1105/tpc.9.11.1951.