Brassinosteroid-6-Oxidases from Arabidopsis and Tomato Catalyze Multiple C-6 Oxidations in Brassinosteroid Biosynthesis

Shimada, Yukihisa; Fujioka, Shozo; Miyauchi, Narumasa; Kushiro, Masayo; Takatsuto, Suguru; Nomura, T.; Yokota, Takao; Kamiya, Yûji; Bishop, Gerard J.; Yoshida, Shigeo

doi:10.1104/pp.126.2.770

Cited by 206 publications

(195 citation statements)

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“…Later in vitro and in vivo studies of BR metabolism (10,14,15,30) revealed that several biosynthetic enzymes have broad specificities for various substrates, resulting in the establishment of a grid-like BR synthesis network (Fig. 1).…”

Section: Discussionmentioning

confidence: 99%

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CYP90A1/CPD, a Brassinosteroid Biosynthetic Cytochrome P450 of Arabidopsis, Catalyzes C-3 Oxidation

Ohnishi

Godza

Watanabe

et al. 2012

Journal of Biological Chemistry

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Background: Recent results raised doubts regarding the earlier proposed C-23 hydroxylase function of CYP90A1/CPD in brassinosteroid biosynthesis. Results: The enzymatic role of CYP90A1/CPD is determined by analytical, genetic, and direct biochemical approaches. Conclusion: CYP90A1 catalyzes C-3 oxidation of early brassinosteroid intermediates. Significance: Our results highlight the primary role of the campestanol-independent pathway in brassinosteroid biosynthesis.

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Section: Discussionmentioning

confidence: 99%

“…1) where broad substrate specificities of the participating enzymes allow metabolite flow via multiple pathways (13)(14)(15). Additionally, most BR biosynthetic genes are up-regulated in BR-deficient mutants (16,17), thereby increasing the role of subsidiary reaction routes.…”

mentioning

confidence: 99%

CYP90A1/CPD, a Brassinosteroid Biosynthetic Cytochrome P450 of Arabidopsis, Catalyzes C-3 Oxidation

Ohnishi

Godza

Watanabe

et al. 2012

Journal of Biological Chemistry

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145

113

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“…Isolation of RNAs and RTQ RT-PCR were performed essentially as described previously (Shimada et al, 2001. In brief, total RNAs were extracted from Arabidopsis seedlings using the guanidine-hydrochloride method.…”

Section: Isolation Of Rnas and Rtq Rt-pcrmentioning

confidence: 99%

Brassinolide InducesIAA5, IAA19, and DR5, a Synthetic Auxin Response Element in Arabidopsis, Implying a Cross Talk Point of Brassinosteroid and Auxin Signaling

et al. 2003

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Despite numerous physiological studies addressing the interactions between brassinosteroids (BRs) and auxins, little is known about the underlying molecular mechanisms. We studied the expression of IAA5 and IAA19 in response to treatment with indole acetic acid (IAA) or brassinolide (BL), the most active BR. Exogenous IAA induced these genes quickly and transiently, whereas exogenous BL induced them gradually and continuously. We also found that a fusion of DR5, a synthetic auxin response element, with the GUS (␤-glucuronidase) gene was induced with similar kinetics to those of the IAA5 and IAA19 genes in response to both IAA and BL treatment of transgenic plants. These results suggest that the IAA genes are induced by BL, at least in part, via the activation of the auxin response element. Endogenous IAA levels per gram fresh weight did not increase when seedlings of Arabidopsis wild type (WT) or the BR-deficient mutant det2 were treated with BL. Furthermore, the levels of IAA transcripts were lower in the det2 mutant than in the WT, even though endogenous IAA levels per gram fresh weight were higher in the det2 mutant than in the WT. In conclusion, the lack of evidence for auxin-mediated activation of early auxin-inducible genes in response to BL suggests that the BR and auxin signaling pathways independently activate the transcriptional system of the IAA and DR5-GUS genes.Exogenous application of brassinosteroids (BRs) to plants at nanomolar to micromolar concentrations produces a wide spectrum of physiological effects. These include promotion of cell elongation and division, enhancement of tracheary element differentiation, delaying of abscission, enhancement of gravityinduced bending, promotion of ethylene biosynthesis, and enhancement of stress resistance, as reviewed by Clouse and Sasse (1998) andSasse (1999). A number of BR-deficient mutants have been identified in Arabidopsis, pea (Pisum sativum), and tomato (Lycopersicon esculentum; for review, see Clouse and Feldmann, 1999;Clouse, 2002; Fujioka and Yokota, 2003). These mutants exhibit dwarfism when grown in either light or dark conditions. Many of these mutants also have dark-green leaves, reduced fertility, a prolonged life span, and abnormal skotomorphogenesis. BR-insensitive mutants have been identified in Arabidopsis, pea, tomato, and rice (Oryza sativa; for review, see Clouse and Feldmann, 1999;Clouse, 2002; Fujioka and Yokota, 2003). The molecular mechanisms of BR action, however, remain unclear.It has been suggested that the actions of BRs are related to auxin action (Mandava, 1988;Sasse, 1999). Synergistic interactions between BRs and auxins occur in elongating tissues and cells in dicots (Yopp et al., 1981;Katsumi, 1985;Sala and Sala, 1985) and in monocots (Yopp et al., 1981). Such synergism is also found in the bending responses of dicots (Yopp et al., 1981; Cohen and Meudt, 1983;Meudt, 1987) and monocots (Takeno and Pharis, 1982; Fujioka et al., 1998). Several authors have proposed that BRinduced effects might be mediated via auxin, wi...

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“…In Arabidopsis, C-6 oxidation is catalyzed by two enzymes, CYP85A1 and CYP85A2, of partially redundant functions. Under in vitro conditions, yeastexpressed CYP85A1 was shown to generate teasterone, typhasterol, and bioactive castasterone from their respective 6-deoxo precursors, whereas CYP85A2, in addition to these reactions, also catalyzed the BaeyerVilliger oxidation of castasterone to BL (Shimada et al, 2001Kim et al, 2005;Nomura et al, 2005). The C-22 and C-23 hydroxylation reactions were found to be mediated by DWF4/CYP90B1 and CPD/CYP90A1, respectively (Szekeres et al, 1996;Choe et al, 1998).…”

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confidence: 99%

Diurnal Regulation of the Brassinosteroid-Biosynthetic CPD Gene in Arabidopsis

et al. 2006

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Plant steroid hormones, brassinosteroids (BRs), are essential for normal photomorphogenesis. However, the mechanism by which light controls physiological functions via BRs is not well understood. Using transgenic plants carrying promoter-luciferase reporter gene fusions, we show that in Arabidopsis (Arabidopsis thaliana) the BR-biosynthetic CPD and CYP85A2 genes are under diurnal regulation. The complex diurnal expression profile of CPD is determined by dual, light-dependent, and circadian control. The severely decreased expression level of CPD in phytochrome-deficient background and the red light-specific induction in wildtype plants suggest that light regulation of CPD is primarily mediated by phytochrome signaling. The diurnal rhythmicity of CPD expression is maintained in brassinosteroid insensitive 1 transgenic seedlings, indicating that its transcriptional control is independent of hormonal feedback regulation. Diurnal changes in the expression of CPD and CYP85A2 are accompanied by changes of the endogenous BR content during the day, leading to brassinolide accumulation at the middle of the light phase. We also show that CPD expression is repressed in extended darkness in a BR feedback-dependent manner. In the dark the level of the bioactive hormone did not increase; therefore, our data strongly suggest that light also influences the sensitivity of plants to BRs.

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Brassinosteroid-6-Oxidases from Arabidopsis and Tomato Catalyze Multiple C-6 Oxidations in Brassinosteroid Biosynthesis

Cited by 206 publications

References 42 publications

CYP90A1/CPD, a Brassinosteroid Biosynthetic Cytochrome P450 of Arabidopsis, Catalyzes C-3 Oxidation

CYP90A1/CPD, a Brassinosteroid Biosynthetic Cytochrome P450 of Arabidopsis, Catalyzes C-3 Oxidation

Brassinolide InducesIAA5, IAA19, and DR5, a Synthetic Auxin Response Element in Arabidopsis, Implying a Cross Talk Point of Brassinosteroid and Auxin Signaling

Diurnal Regulation of the Brassinosteroid-Biosynthetic CPD Gene in Arabidopsis

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