Squalene cyclase and oxidosqualene cyclase from a fern

Shinozaki, Junichi; Shibuya, Masabumi; Masuda, Kazuo; Ebizuka, Yutaka

doi:10.1016/j.febslet.2007.12.023

Cited by 46 publications

(38 citation statements)

References 33 publications

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“…Some of these structures are identical to bacterial hopanoids. For example, several members of the Polypodiales (polypod) order of ferns encode an SHC enzyme 24 that seems to exclusively produce the C 30 hopanoid diplopterol in vitro 27 . It is likely that these ferns acquired shc by horizontal transfer from bacteria 28 .…”

Section: Hopanoid Structure and Biosynthesismentioning

confidence: 99%

Hopanoid lipids: from membranes to plant–bacteria interactions

et al. 2018

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Lipid research represents a frontier for microbiology, as showcased by hopanoid lipids. Hopanoids, which resemble sterols and are found in the membranes of diverse bacteria, have left an extensive molecular fossil record. They were first discovered by petroleum geologists. Today, hopanoid-producing bacteria remain abundant in various ecosystems, such as the rhizosphere. Recently, great progress has been made in our understanding of hopanoid biosynthesis, facilitated in part by technical advances in lipid identification and quantification. A variety of genetically tractable, hopanoid-producing bacteria have been cultured, and tools to manipulate hopanoid biosynthesis and detect hopanoids are improving. However, we still have much to learn regarding how hopanoid production is regulated, how hopanoids act biophysically and biochemically, and how their production affects bacterial interactions with other organisms, such as plants. The study of hopanoids thus offers rich opportunities for discovery.

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Section: Hopanoid Structure and Biosynthesismentioning

confidence: 99%

Hopanoid lipids: from membranes to plant–bacteria interactions

et al. 2018

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“…Changes in expression in a BY-2 control line (transformed with the empty vector, pER8.1) are also shown regulatory details are still obscure. In this contribution, we focused our attention on one key enzyme in the pathway, CAS [14,15,23,[43][44][45], and on its regulatory role in the well-established tobacco BY-2 cell system [33,34]. Admittedly, observations on cell cultures may not always hold true for intact plants.…”

Section: Different Approaches To Analysis Of Phytosterol Biosynthesismentioning

confidence: 98%

Inhibition of Cycloartenol Synthase (CAS) Function in Tobacco BY‐2 Cells

Gas-Pascual¹,

Simonovik²,

Schaller³

et al. 2015

Lipids

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Tobacco BY-2 cell suspensions are our preferred model for studying isoprenoid biosynthesis pathways, due to their easy genetic transformation and the efficient absorption of metabolic precursors, intermediates, and/or inhibitors. Using this model system, we have analyzed the effects of chemical and genetic blockage of cycloartenol synthase (CAS, EC 5.4.99.8), an oxidosqualene cyclase that catalyzes the first committed step in the sterol pathway of plants. BY-2 cells were treated with RO 48-8071, a potent inhibitor of oxidosqualene cyclization. Short-term treatments (24 h) resulted in accumulation of oxidosqualene with no changes in the final sterol products. Interestingly, long-term treatments (6 days) induced down-regulation in gene expression not only of CAS but also of the SMT2 gene coding sterol methyltransferase 2 (EC 2.1.1.41). This explains some of the increase in 24-methyl sterols at the expense of the 24-ethyl sterols stigmasterol and sitosterol. In our alternative strategy, CAS gene expression was partially blocked by using an inducible artificial microRNA. The limited effectiveness of this approach might be explained by some dependence of the machinery for RNAi formation on an operating MVA/sterol pathway. For comparison we checked the effect of RO 48-8071 on a green cell suspension of Arabidopsis and on seedlings, containing a small spectrum of triterpenes besides phytosterols. Triterpenes remained essentially unaffected, but phytosterol accumulation was clearly diminished.

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“…They belong to the OSC family and catalyze the transformation of oxidosqualene of chair-boat-chairboat and reorganize the cytoskeleton to produce cycloartenol (Wang et al 2010) and lanosterol. The authors cloned and identified CAS from different plants including Arabidopsis thaliana (Babiychuk et al 2008), fern (Shinozaki et al 2008), Kalanchoe daigremontiana (Wang et al 2010) and Huperzia carinata (Niu et al 2012). Cloning was necessary because of the low concentrations found in plants; however, the community has failed to appreciate the distribution of LAS catalyses in the production of ergosterol and cholesterol.…”

Section: Phytochem Revmentioning

confidence: 98%

Phytochemistry and biosynthesis of δ-lactone withanolides

et al. 2015

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Withanolides are highly oxygenated natural products. These C 28 steroids with ergostane-based skeletons functionalized at C-22 and C-26 form sixmembered d-lactone rings. Withanolides containing a d-lactone side chain often occur in Solanaceae and have a variety of biological activities because of their complicated structures. Characteristic spectroscopic behaviors and biosynthesis of withanolides are conducive to their structural elucidation and ''biomimetic synthesis'', respectively. However, the last review to summarize their spectroscopic features and biosynthesis was in 1996. Since then, many withanolides with novel structures have been described by their spectra with biosynthesis investigated with many bioassays. This review surveys d-lactone withanolides and emphasizes their spectral features, configurations and biosynthetic genes. The period reviewed includes through January 2014. We also include phytochemical species.

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Squalene cyclase and oxidosqualene cyclase from a fern

Cited by 46 publications

References 33 publications

Hopanoid lipids: from membranes to plant–bacteria interactions

Hopanoid lipids: from membranes to plant–bacteria interactions

Inhibition of Cycloartenol Synthase (CAS) Function in Tobacco BY‐2 Cells

Phytochemistry and biosynthesis of δ-lactone withanolides

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