Enhanced seed phytosterol accumulation through expression of a modified HMG‐CoA reductase

Hey, Sandra J.; Powers, Stephen J.; Beale, Michael H.; Hawkins, Nathaniel D.; Ward, Jane L.; Halford, Nigel G.

doi:10.1111/j.1467-7652.2005.00174.x

Cited by 75 publications

(39 citation statements)

References 34 publications

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“…High HMGR expression in the early developmental stage has also been shown in other plants: potato (Solanum tuberosum) HMGR1 is expressed in the early flower developmental stage (Korth et al, 1997), and tomato (Solanum lycopersicum) HMGR1 is expressed in young tomato fruit (Jelesko et al, 1999). The flower phenotype in tobacco (Nicotiana tabacum) is altered by the overexpression of AtHMGR1 (Hey et al, 2006), which suggests that HMGRderived phytosterols and metabolites play roles in flower development (Fig. 6B).…”

Section: Tissue-specific Expression Patterns and Developmental Roles supporting

confidence: 58%

Functional Analysis of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Encoding Genes in Triterpene Saponin-Producing Ginseng

et al. 2014

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Ginsenosides are glycosylated triterpenes that are considered to be important pharmaceutically active components of the ginseng (Panax ginseng 'Meyer') plant, which is known as an adaptogenic herb. However, the regulatory mechanism underlying the biosynthesis of triterpene saponin through the mevalonate pathway in ginseng remains unclear. In this study, we characterized the role of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) concerning ginsenoside biosynthesis. Through analysis of full-length complementary DNA, two forms of ginseng HMGR (PgHMGR1 and PgHMGR2) were identified as showing high sequence identity. The steady-state mRNA expression patterns of PgHMGR1 and PgHMGR2 are relatively low in seed, leaf, stem, and flower, but stronger in the petiole of seedling and root. The transcripts of PgHMGR1 were relatively constant in 3-and 6-year-old ginseng roots. However, PgHMGR2 was increased five times in the 6-year-old ginseng roots compared with the 3-year-old ginseng roots, which indicates that HMGRs have constant and specific roles in the accumulation of ginsenosides in roots. Competitive inhibition of HMGR by mevinolin caused a significant reduction of total ginsenoside in ginseng adventitious roots. Moreover, continuous dark exposure for 2 to 3 d increased the total ginsenosides content in 3-year-old ginseng after the dark-induced activity of PgHMGR1. These results suggest that PgHMGR1 is associated with the dark-dependent promotion of ginsenoside biosynthesis. We also observed that the PgHMGR1 can complement Arabidopsis (Arabidopsis thaliana) hmgr1-1 and that the overexpression of PgHMGR1 enhanced the production of sterols and triterpenes in Arabidopsis and ginseng. Overall, this finding suggests that ginseng HMGRs play a regulatory role in triterpene ginsenoside biosynthesis.

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Section: Tissue-specific Expression Patterns and Developmental Roles supporting

confidence: 58%

Functional Analysis of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Encoding Genes in Triterpene Saponin-Producing Ginseng

et al. 2014

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“…by the mevalonate pathway such as phytosterols by removing the potential phosphorylation site to avoid negative regulation of the enzyme activity has also been an emerging strategy (Hey et al 2006;Pütter et al 2017). Although the negative regulation of HMGR through phosphorylation is likely to occur in planta, it has not been experimentally verified.…”

Section: Discussionmentioning

confidence: 99%

Evidence that the <i>Arabidopsis thaliana</i> 3-hydroxy-3-methylglutaryl-CoA reductase 1 is phosphorylated at Ser577 <i>in planta</i>

Robertlee

Kobayashi

Tang

et al. 2018

Plant Biotechnology

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3-Hydroxy-3-methylglutaryl-CoA reductase (HMGR) is an essential enzyme in the mevalonate pathway. In higher plants, mevalonate pathway involves in the production of precursor for isoprenoids biosynthesis, including essential components for cell functions. Previously, we confirmed that the Arabidopsis thaliana HMGR1S (AtHMGR1S) is phosphorylated at S577 by the combination of sucrose non-fermenting related kinase-1 (SnRK1) and geminivirus repinteracting kinase-1 (GRIK1) in vitro. However, even in quantitative phosphoproteomics studies that were directed to find SnRK1 target substrates, AtHMGR1S phosphorylation at S577 has never been detected in planta. In this study, we expressed AtHMGR1S as a C-terminal FLAG-fusion protein in A. thaliana hmg1 mutant to confirm its phosphorylation in planta. Our results provide the first direct evidence that AtHMGR1S is phosphorylated at S577 in planta. Moreover, phosphatase inhibitors treatment to the A. thaliana seedlings induced AtHMGR1S phosphorylation at sites other than S577, suggesting the presence of a novel HMGR regulatory mechanism in planta.

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“…However, limited quantities of phytosterols are currently a major barrier in satisfying the demands for such functional foods. Based on a firmly established concept that 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) plays a rate-limiting role in the flux control of sterol biosynthesis (Bach, 1986;Gondet et al, 1992Gondet et al, , 1994Chappell et al, 1995), efforts aimed at increasing phytosterol content have been concentrated on enhancing the activity of HMGR through introducing modified HMGR that is resistant to regulation (Chappell et al, 1995;Re et al, 1995;Schaller et al, 1995;Harker et al, 2003;Hey et al, 2006). Nonetheless, evidence suggesting the existence of other regulatory step(s) in the flux control of sterol biosynthesis can be found in some studies, particularly that of Gondet et al (1994) who studied a steroloverproducing tobacco (Nicotiana tabacum) mutant LAB1-4, with HMGR levels approximately 3-fold higher than normal (Gondet et al, 1994).…”

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confidence: 99%

Biosynthesis of Phytosterol Esters: Identification of a Sterol O-Acyltransferase in Arabidopsis

et al. 2007

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Fatty acyl esters of phytosterols are a major form of sterol conjugates distributed in many parts of plants. In this study we report an Arabidopsis (Arabidopsis thaliana) gene, AtSAT1 (At3g51970), which encodes for a novel sterol O-acyltransferase. When expressed in yeast (Saccharomyces cerevisiae), AtSAT1 mediated production of sterol esters enriched with lanosterol. Enzyme property assessment using cell-free lysate of yeast expressing AtSAT1 suggested the enzyme preferred cycloartenol as acyl acceptor and saturated fatty acyl-Coenyzme A as acyl donor. Taking a transgenic approach, we showed that Arabidopsis seeds overexpressing AtSAT1 accumulated fatty acyl esters of cycloartenol, accompanied by substantial decreases in ester content of campesterol and b-sitosterol. Furthermore, fatty acid components of sterol esters from the transgenic lines were enriched with saturated and long-chain fatty acids. The enhanced AtSAT1 expression resulted in decreased level of free sterols, but the total sterol content in the transgenic seeds increased by up to 60% compared to that in wild type. We conclude that AtSAT1 mediates phytosterol ester biosynthesis, alternative to the route previously described for phospholipid:sterol acyltransferase, and provides the molecular basis for modification of phytosterol ester level in seeds.

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Enhanced seed phytosterol accumulation through expression of a modified HMG‐CoA reductase

Cited by 75 publications

References 34 publications

Functional Analysis of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Encoding Genes in Triterpene Saponin-Producing Ginseng

Functional Analysis of 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Encoding Genes in Triterpene Saponin-Producing Ginseng

Evidence that the <i>Arabidopsis thaliana</i> 3-hydroxy-3-methylglutaryl-CoA reductase 1 is phosphorylated at Ser577 <i>in planta</i>

Biosynthesis of Phytosterol Esters: Identification of a Sterol O-Acyltransferase in Arabidopsis

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