The Arabidopsis DIMINUTO/DWARF1 gene encodes a protein involved in steroid synthesis.
We have identified the function of the Arabidopsis DIMINUTO/DWARF1 (DIM/DWF1) gene by analyzing the dim mutant, a severe dwarf with greatly reduced fertility. Both the mutant phenotype and gene expression could be rescued by the addition of exogenous brassinolide. Analysis of endogenous sterols demonstrated that dim accumulates 24-methylenecholesterol but is deficient in campesterol, an early precursor of brassinolide. In addition, we show that dim is deficient in brassinosteroids as well. Feeding experiments using deuterium-labeled 24-methylenecholesterol and 24-methyldesmosterol confirmed that DIM/DWF1 is involved in both the isomerization and reduction of the Delta24(28) bond. This conversion is not required in cholesterol biosynthesis in animals but is a key step in the biosynthesis of plant sterols. Transient expression of a green fluorescent protein-DIM/DWF1 fusion protein and biochemical experiments showed that DIM/DWF1 is an integral membrane protein that most probably is associated with the endoplasmic reticulum.
Laboratory of Plant Molecular Biology, The Rockefeller University, 1230 York Avenue, New York, New York 10021-6399, USA.
U
U
Klahre
T
T
Noguchi
S
S
Fujioka
S
S
Takatsuto
T
T
Yokota
T
T
Nomura
S
S
Yoshida
N H
NH
Chua
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D029681:Arabidopsis Proteins; D001483:Base Sequence; D060406:Brassinosteroids; D002777:Cholestanols / Q000378:metabolism / Q000494:pharmacology; D002784:Cholesterol / Q000031:analogs & derivatives / Q000378:metabolism; D018744:DNA, Plant / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D010840:Phytosterols; D010937:Plant Growth Regulators / Q000378:metabolism / Q000494:pharmacology; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013256:Steroids / Q000096:biosynthesis*; D013260:Steroids, Heterocyclic / Q000378:metabolism / Q000494:pharmacology; D013265:Stigmasterol / Q000031:analogs & derivatives / Q000378:metabolism
D029681:Arabidopsis Proteins; D060406:Brassinosteroids; D002777:Cholestanols; C091574:DIM1 protein, Arabidopsis; D018744:DNA, Plant; D008565:Membrane Proteins; D010840:Phytosterols; D010937:Plant Growth Regulators; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D013256:Steroids; D013260:Steroids, Heterocyclic; C015896:fucosterol; C021273:campesterol; D002784:Cholesterol; D013265:Stigmasterol; C002537:24-methylenecholesterol; C023623:brassinolide