Dataset Information

Plant sterol metabolism. ?(7)-Sterol-C5-desaturase (STE1/DWARF7), ?(5,7)-sterol-?(7)-reductase (DWARF5) and ?(24)-sterol-?(24)-reductase (DIMINUTO/DWARF1) show multiple subcellular localizations in Arabidopsis thaliana (Heynh) L.

ABSTRACT: Sterols are crucial lipid components that regulate membrane permeability and fluidity and are the precursors of bioactive steroids. The plant sterols exist as three major forms, free sterols, steryl glycosides and steryl esters. The storage of steryl esters in lipid droplets has been shown to contribute to cellular sterol homeostasis. To further document cellular aspects of sterol biosynthesis in plants, we addressed the question of the subcellular localization of the enzymes implicated in the final steps of the post-squalene biosynthetic pathway. In order to create a clear localization map of steroidogenic enzymes in cells, the coding regions of ?(7)-sterol-C(5)-desaturase (STE1/DWARF7), ?(24)-sterol-?(24)-reductase (DIMINUTO/DWARF1) and ?(5,7)-sterol-?(7)-reductase (DWARF5) were fused to the yellow fluorescent protein (YFP) and transformed into Arabidopsis thaliana mutant lines deficient in the corresponding enzymes. All fusion proteins were found to localize in the endoplasmic reticulum in functionally complemented plants. The results show that both ?(5,7)-sterol-?(7)-reductase and ?(24)-sterol-?(24)-reductase are in addition localized to the plasma membrane, whereas ?(7)-sterol-C(5)-desaturase was clearly detected in lipid particles. These findings raise new challenging questions about the spatial and dynamic cellular organization of sterol biosynthesis in plants.

SUBMITTER: Silvestro D

PROVIDER: S-EPMC3568079 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Publications

Plant sterol metabolism. Δ(7)-Sterol-C5-desaturase (STE1/DWARF7), Δ(5,7)-sterol-Δ(7)-reductase (DWARF5) and Δ(24)-sterol-Δ(24)-reductase (DIMINUTO/DWARF1) show multiple subcellular localizations in Arabidopsis thaliana (Heynh) L.

Silvestro Daniele D Andersen Tonni Grube TG Schaller Hubert H Jensen Poul Erik PE

PloS one 20130208 2

Sterols are crucial lipid components that regulate membrane permeability and fluidity and are the precursors of bioactive steroids. The plant sterols exist as three major forms, free sterols, steryl glycosides and steryl esters. The storage of steryl esters in lipid droplets has been shown to contribute to cellular sterol homeostasis. To further document cellular aspects of sterol biosynthesis in plants, we addressed the question of the subcellular localization of the enzymes implicated in the f ...[more]

PMID: 23409184

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Project description:BackgroundSterols are structural and functional components of eukaryotic cell membranes. Plants produce a complex mixture of sterols, among which β-sitosterol, stigmasterol, campesterol, and cholesterol in some Solanaceae, are the most abundant species. Many reports have shown that the stigmasterol to β-sitosterol ratio changes during plant development and in response to stresses, suggesting that it may play a role in the regulation of these processes. In tomato (Solanum lycopersicum), changes in the stigmasterol to β-sitosterol ratio correlate with the induction of the only gene encoding sterol C22-desaturase (C22DES), the enzyme specifically involved in the conversion of β-sitosterol to stigmasterol. However, despite the biological interest of this enzyme, there is still a lack of knowledge about several relevant aspects related to its structure and function.ResultsIn this study we report the subcellular localization of tomato C22DES in the endoplasmic reticulum (ER) based on confocal fluorescence microscopy and cell fractionation analyses. Modeling studies have also revealed that C22DES consists of two well-differentiated domains: a single N-terminal transmembrane-helix domain (TMH) anchored in the ER-membrane and a globular (or catalytic) domain that is oriented towards the cytosol. Although TMH is sufficient for the targeting and retention of the enzyme in the ER, the globular domain may also interact and be retained in the ER in the absence of the N-terminal transmembrane domain. The observation that a truncated version of C22DES lacking the TMH is enzymatically inactive revealed that the N-terminal membrane domain is essential for enzyme activity. The in silico analysis of the TMH region of plant C22DES revealed several structural features that could be involved in substrate recognition and binding.ConclusionsOverall, this study contributes to expand the current knowledge on the structure and function of plant C22DES and to unveil novel aspects related to plant sterol metabolism.

Dataset Information

Plant sterol metabolism. ?(7)-Sterol-C5-desaturase (STE1/DWARF7), ?(5,7)-sterol-?(7)-reductase (DWARF5) and ?(24)-sterol-?(24)-reductase (DIMINUTO/DWARF1) show multiple subcellular localizations in Arabidopsis thaliana (Heynh) L.

Publications

Plant sterol metabolism. Δ(7)-Sterol-C5-desaturase (STE1/DWARF7), Δ(5,7)-sterol-Δ(7)-reductase (DWARF5) and Δ(24)-sterol-Δ(24)-reductase (DIMINUTO/DWARF1) show multiple subcellular localizations in Arabidopsis thaliana (Heynh) L.

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