scholarly journals Catalytic flexibility of rice glycosyltransferase OsUGT91C1 for the production of palatable steviol glycosides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jinzhu Zhang ◽  
Minghai Tang ◽  
Yujie Chen ◽  
Dan Ke ◽  
Jie Zhou ◽  
...  

AbstractSteviol glycosides are the intensely sweet components of extracts from Stevia rebaudiana. These molecules comprise an invariant steviol aglycone decorated with variable glycans and could widely serve as a low-calorie sweetener. However, the most desirable steviol glycosides Reb D and Reb M, devoid of unpleasant aftertaste, are naturally produced only in trace amounts due to low levels of specific β (1–2) glucosylation in Stevia. Here, we report the biochemical and structural characterization of OsUGT91C1, a glycosyltransferase from Oryza sativa, which is efficient at catalyzing β (1–2) glucosylation. The enzyme’s ability to bind steviol glycoside substrate in three modes underlies its flexibility to catalyze β (1–2) glucosylation in two distinct orientations as well as β (1–6) glucosylation. Guided by the structural insights, we engineer this enzyme to enhance the desirable β (1–2) glucosylation, eliminate β (1–6) glucosylation, and obtain a promising catalyst for the industrial production of naturally rare but palatable steviol glycosides.

Biomolecules ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 27 ◽  
Author(s):  
Zheng Yang ◽  
Brandon Uhler ◽  
Ted Zheng ◽  
Kristie Adams

Zero-calorie high-intensity sweeteners from natural sources perform very well in the market place. This has encouraged food scientists to continue the effort to search for novel natural ingredients to satisfy consumer demand. Rebaudioside C (reb C) is the third most prevalent steviol glycoside in the leaves of the Stevia rebaudiana Bertoni plant, but has limited applications in food and beverage products due to its low sweetness and high lingering bitterness compared to other major steviol glycosides, such as rebaudioside A (reb A). Here we present a new enzyme modification strategy to improve the taste profile of reb C by using Cargill’s propriety enzyme and sucrose as a glucose donor. A novel α-1→6-glucosyl reb C derivative was produced and its structure was elucidated by mass spectrometry and NMR spectroscopy. Sensory analysis demonstrated that this new reb C derivative has improved sweetness, reduced bitterness, and enhanced solubility in water.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Eva Petit ◽  
Monique Berger ◽  
Laurent Camborde ◽  
Veronica Vallejo ◽  
Jean Daydé ◽  
...  

Abstract Glycosylation is a key modification that contributes to determine bioactivity and bioavailability of plant natural products, including that of terpenoids and steviol glycosides (SVglys). It is mediated by uridine-diphosphate glycosyltransferases (UGTs), that achieve their activity by transferring sugars on small molecules. Thus, the diversity of SVglys is due to the number, the position and the nature of glycosylations on the hydroxyl groups in C-13 and C-19 of steviol. Despite the intense sweetener property of SVglys and the numerous studies conducted, the SVglys biosynthetic pathway remains largely unknown. More than 60 SVglys and 68 putative UGTs have been identified in Stevia rebaudiana. This study aims to provide methods to characterize UGTs putatively involved in SVglys biosynthesis. After agroinfiltration-based transient gene expression in Nicotiana benthamiana, functionality of the recombinant UGT can be tested simply and directly in plants expressing it or from a crude extract. The combined use of binary vectors from pGWBs series to produce expression vectors containing the stevia's UGT, enables functionality testing with many substrates as well as other applications for further analysis, including subcellular localization.


2018 ◽  
Vol 10 (3) ◽  
pp. 353 ◽  
Author(s):  
Felipe Francisco ◽  
Gabriely Pinto Pereira ◽  
Marília Pereira Machado ◽  
Luiz Alberto Kanis ◽  
Cícero Deschamps

Stevia, a native species of South America, is commercially important as a source of the non-caloric diterpene glycosides stevioside and rebaudioside-A. Although it has been cultivated in southern Brazil, the production is not enough to meet the domestic market demand. This study evaluated biomass accumulation, morphological and physiological characters, and steviol glycosides yield of seven stevia accessions after two cuts. A great variation for the different plant characteristics was found between the first and second cuts. There was a positive correlation between biomass production and SGs content and productivity. The overall Principal Components Analysis results in both cuts indicate that the accessions CE7 and CE14 presented great Reb-A yield, height and lodging (%). The accessions CE4 and CE12 produced high Ste yield and accessions CE6, CE8 and CE9 the highest leaf:stem ratio and low SGs. The stevia accessions showed characteristics of the interest for crop improvement for both biomass and SGs production.


2017 ◽  
Vol 9 (4) ◽  
pp. 2114-2126 ◽  
Author(s):  
Neena Kumari ◽  
Suresh Kumar

The Stevia genus encompasses about 200 herbs and shrubs species. Stevia rebaudiana, one of the members has gained commercial importance as a natural low calorie sweetener, due to the presence of high con-centration of stevioside and rebaudioside - A (25% to 45% of stevioside content) in the leaves. The major processes involved in the production and quantification of steviol glycosides are extraction, purification and estimation. Various extraction methods have been used for extraction of steviol glycosides in the world. The extraction methods of steviol glycosides mostly differed at the stage of clarification of extracts. The present study is an attempt to summarize the scattered literature and reports on a single podium. Moreover, it also depicts up to date literature regarding numerous extraction, purification and quantitative estimation methods for steviol glycosides


2014 ◽  
Vol 62 (49) ◽  
pp. 11797-11804 ◽  
Author(s):  
María Inés Espinoza ◽  
Jean-Paul Vincken ◽  
Mark Sanders ◽  
Cristian Castro ◽  
Markus Stieger ◽  
...  

2015 ◽  
Vol 61 (1) ◽  
pp. 50-63 ◽  
Author(s):  
Aleksandra Luwańska ◽  
Aleksandra Perz ◽  
Grażyna Mańkowska ◽  
Karolina Wielgus

Summary Stevia is a plant attracting attention due to its capability to synthesize a group of chemical compounds with sweet taste, i.e. steviol glycosides. Steviol glycosides are successfully applied as a natural sweetener, and some of them have also therapeutic properties. This paper presents available information on the use of stevia plant tissue cultures with the focus on their potential application in food industry. Detailed analysis was done concerning the research employing in vitro culture techniques and the use of them in biosynthesis of secondary metabolites of high importance for the food industry. Both established achievements and most recent publications on stevia were used for assessment of practical applications of the aforementioned techniques and prospects for their development.


2019 ◽  
Vol 14 (6) ◽  
pp. 1934578X1986000 ◽  
Author(s):  
Zheng Yang ◽  
Brandon Uhler ◽  
Tristan Lipkie

A rapid method that combines microwave heating and subcritical water extraction to extract steviol glycosides from Stevia rebaudiana (Bertoni) or stevia leaves was developed and compared to conventional thermal solvent extraction methods. Within only 1 minute after subcritical water condition at 140°C being reached, the yields of major steviol glycoside, rebaudioside A and stevioside, and less polar steviol glucoside, rebaudioside C, from stevia leaves were comparable to conventional extraction method that used 70% ethanol under sonication for 45 minutes. This new hybrid extraction technique may provide a cost-effective and green approach for commercial production of high-purity steviol glycoside sweeteners and their “organic” versions without the use of highly expensive “organic” ethanol.


HortScience ◽  
2015 ◽  
Vol 50 (10) ◽  
pp. 1479-1485 ◽  
Author(s):  
Jennifer M. Evans ◽  
Veronica A. Vallejo ◽  
Randolph M. Beaudry ◽  
Ryan M. Warner

The biosynthesis of steviol glycosides is affected by both genetic and environmental factors. To evaluate the influence of total daily solar radiation or daily light integral (DLI) under long-day conditions on steviol glycoside concentration, we grew Stevia rebaudiana under ambient irradiance or varying levels of shading at different times of the year in both greenhouse and field environments, resulting in DLIs ranging from 3.55 to 20.31 mol·m−2·d−1 in the greenhouse and 10.32 to 39.7 mol·m−2·d−1 in the field. Total steviol glycoside concentration of selected leaves from greenhouse-grown plants increased as DLI increased up to ca. 10 mol·m−2·d−1, remaining constant with further increases in DLI, and was similar across the range of DLIs evaluated in the field. DLI influenced both the concentration and the relative proportions of specific steviol glycosides. Rebaudioside A concentration increased as DLI increased from 3.55 to 8.53 mol·m−2·d−1, remaining similar with further increases in DLI. Rebaudioside D and stevioside concentration of selected leaves from field-grown plants decreased by 22% and 13%, respectively, as DLI increased from 10.32 to 39.7 mol·m−2·d−1, while rebaudioside A and M concentrations remained similar across this DLI range. Collectively, these results indicate that the greatest influence of DLI on steviol glycoside concentration occurs under relatively low DLIs (<10 mol·m−2·d−1). However, higher DLIs can significantly affect the synthesis of minor glycosides of increasing commercial importance including rebaudioside D.


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