Biocatalytic Synthesis of Quercetin 3‐ O ‐Glucoside‐7‐ O ‐Rhamnoside by Metabolic Engineering of Escherichia coli

Amirsadeghi

McKenzie‐Gopsill

et al. 2016

Planta

The interaction between neighboring weed-induced far-red enriched light and thiamethoxam can significantly alter soybean seedling morphology, nodulation, isoflavone levels, UV-absorbing phenolics, and carbon and nitrogen content. Neonicotinoid insecticides that are widely used on major crop plants can enhance plant growth and yield. Although the underlying mechanism of this enhanced growth and yield is not clear, recent studies suggest that neonicotinoids such as thiamethoxam (TMX) may exert their effects at least in part via signals that involve salicylic acid (SA) and jasmonic acid (JA). In the current research, effects of TMX on morphological and physiological responses of soybean have been compared under far-red-depleted (FR-D) and far-red-enriched (FR-E) light reflected by neighboring weeds. TMX significantly enhanced shoot and root growth but did not prevent stem elongation under FR-E light. Also, TMX did not prevent reductions in shoot carbon content and shoot carbon to nitrogen ratio under FR-E light. Despite similarities between these TMX effects in soybean and those known for SA and JA in other plant species, TMX significantly enhanced root-nodule numbers per plant and levels of root isoflavones malonyl-daidzin and malonyl-genistin under FR-E light only. These results suggest that the combined effect of FR-E light and TMX triggers a mechanism that operates concomitantly to enhance root isoflavones and nodulation in soybean.

Section: Isoflavone Analysismentioning

confidence: 99%

Changes in light quality alter physiological responses of soybean to thiamethoxam

Amirsadeghi

McKenzie‐Gopsill

et al. 2016

Planta

Journal of Biological Chemistry

“…analysis was carried as described previously (22,60) with slight modifications using Nexera UHPLC (130 megapascals) equipped with MS-8030 (Shimadzu). Enable RP-C18 column (250 ϫ 4.6 mm, 5 m) was used for the analysis.…”

Section: Lc-esi-ms Analysis-lc-msmentioning

confidence: 99%

Functional Characterization of CsBGlu12, a β-Glucosidase from Crocus sativus, Provides Insights into Its Role in Abiotic Stress through Accumulation of Antioxidant Flavonols

Baba

Vishwakarma

Ashraf

2017

Edited by Joseph JezGlycosylation and deglycosylation are impressive mechanisms that allow plants to regulate the biological activity of an array of secondary metabolites. Although glycosylation improves solubility and renders the metabolites suitable for transport and sequestration, deglycosylation activates them to carry out biological functions. Herein, we report the functional characterization of CsBGlu12, a ␤-glucosidase from Crocus sativus. CsBGlu12 has a characteristic glucoside hydrolase 1 family (␣/␤) 8 triose-phosphate isomerase (TIM) barrel structure with a highly conserved active site. In vitro enzyme activity revealed that CsBGlu12 catalyzes the hydrolysis of flavonol ␤-glucosides and cello-oligosaccharides. Site-directed mutagenesis of any of the two conserved catalytic glutamic acid residues (Glu 200 and Glu 414 ) of the active site completely abolishes the ␤-glucosidase activity. Transcript analysis revealed that Csbglu12 is highly induced in response to UV-B, dehydration, NaCl, methyl jasmonate, and abscisic acid treatments indicating its possible role in plant stress response. Transient overexpression of CsBGlu12 leads to the accumulation of antioxidant flavonols in Nicotiana benthamiana and confers tolerance to abiotic stresses. Antioxidant assays indicated that accumulation of flavonols alleviated the accretion of reactive oxygen species during abiotic stress conditions. ␤-Glucosidases are known to play a role in abiotic stresses, particularly dehydration through abscisic acid; however, their role through accumulation of reactive oxygen species (ROS) scavenging flavonols has not been established. Furthermore, only one ␤-glucosidase 12 homolog has been characterized so far. Therefore, this work presents an important report on characterization of CsBGlu12 and its role in abiotic stress through ROS scavenging.Plants are sessile organisms that cannot escape their predators and the harsh environmental conditions. However, during the course of evolution, plants have learned to defend themselves and adapt to different types of biotic and abiotic stresses by synthesizing a diverse assortment of secondary metabolites. Many of these secondary metabolites are stored in inactive glycosylated forms. The glycosylation chemically stabilizes and enhances the solubility of the metabolites and renders them fit for storage in the vacuole and more so to protect the plant from the noxious effects of its own defense system (1). These glyconjugates are activated by the hydrolysis of the ␤-glucosidic bond by a class of enzymes called ␤-glucosidases. ␤-Glucosidases (EC 3.2.1.2.1) belong to family 1 of glycoside hydrolases and perform diverse and vital functions in plants, which include, but are not limited to, the activation of lignin precursors (2), release of glucose from oligosaccharides (3), release of phytohormones from inactive glycosides (4), and activation of several defense compounds (5-9). This process of glycosylation and deglycosylation offers an efficient mechanism that regulates the homeostasis of secon...

“…These flavonol-O-diglycosides contain a combination of rhamnose, glucose, and arabinose at the 3 and 7 hydroxyl groups of flavonols such as kaempferol and quercetin (YonekuraSakakibara et al 2008). E. coli was also used to synthesize these flavonol diglycosides (Kim et al 2013a;Roepke and Bozzo 2013). Quercetin-3-O-glucoside-7-O-rhamnoside was synthesized by two approaches.…”

Section: Synthesis Of Flavonoid Diglycosides In E Colimentioning

confidence: 99%

Biosynthesis and production of glycosylated flavonoids in Escherichia coli: current state and perspectives

Yang

Appl Microbiol Biotechnol

et al. 2015

Flavonoids are plant secondary metabolites containing several hydroxyl groups that are targets for modification reactions such as methylation and glycosylation. In plants, flavonoids are present as glycones. Although glucose is the most common sugar attached to flavonoids, arabinose, galactose, glucuronic acid, rhamnose, and xylose are also linked to flavonoids. Depending on the kind and the position of the attached sugar, flavonoid glycones show different biological properties. Flavonoid-O-glycosides are synthesized by uridine diphosphate-dependent glycosyltransferases (UGTs), which use nucleotide sugar as a sugar donor and a diverse compound as a sugar acceptor. Recently, diverse flavonoid-O-glycosides have been synthesized in Escherichia coli by introducing UGTs from plants and bacteria and modifying endogenous pathways. The nucleotide sugar biosynthesis pathway in E. coli has been engineered to provide the proper nucleotide sugar for flavonoid-O-glycoside biosynthesis. In this review, we will discuss recent advances in flavonoid-O-glycoside biosynthesis using engineered E. coli.