4,6-α-glucosyltransferases (4,6-α-GTs), which converts amylose into α(1-6) bonds-containing α-glucan, possesses great application potential in enzymatic synthesis of dietary fiber. Primers were designed according to the conserved motifs existing in the amino acid sequence of 4,6-α-GTs, and used to amplify a putative GTFB-Like 4,6-α-GTs gene (named as gtf16) from the genomic DNA of Lactobacillus. The gtf16 gene was cloned into the plasmid pET15b, expressed in Escherichia coli BL21(DE3), followed by purification and characterization. The optimum pH and the optimum temperature of the purified enzyme were 5.0 and 40 °C, respectively. The biotransformation product of this enzyme was systematically characterized by thin-layer chromatography, NMR spectroscopy, and hydrolysis reaction. The Gtf16-catalyzed product shows a similar structure to that of the isomalto/malto-polysaccharide (IMMP), which is the amylose-derived product catalyzed by GtfB from Lactobacillus reuteri 121. Moreover, The Gtf16-catalyzed product contains up to 75% of α(1-6) bonds and has an average molecular weight of 23 793 Da. Furthermore, the content of the anti-digestive components was 88.22% upon hydrolysis with digestive enzymes.
Bacterial Proteins/genetics* ; Glucans ; Glucosyltransferases/genetics* ; Lactobacillus fermentum/enzymology*

Water solubility, stability, and bioavailability, can be substantially improved after glycosylation. Glycosylation of bioactive compounds catalyzed by glycoside hydrolases (GHs) and glycosyltransferases (GTs) has become a research hotspot. Thanks to their rich sources and use of cheap glycosyl donors, GHs are advantageous in terms of scaled catalysis compared to GTs. Among GHs, sucrose phosphorylase has attracted extensive attentions in chemical engineering due to its prominent glycosylation activity as well as its acceptor promiscuity. This paper reviews the structure, catalytic characteristics, and directional redesign of sucrose phosphorylase. Meanwhile, glycosylation of diverse chemicals with sucrose phosphorylase and its coupling applications with other biocatalysts are summarized. Future research directions were also discussed based on the current research progress combined with our working experience.
Glucosyltransferases/metabolism* ; Glycoside Hydrolases/metabolism* ; Glycosylation ; Glycosyltransferases/genetics*

To investigate the mechanism of high product specificity of gamma-clodextrin glucanotransferase (CGTase) from alkalophilic Bacillus clarkii 7364, we aligned protein sequence and structure model, found out that loss of 6 amino acids at subsite -7 probably affected its product specificity. Using overlapping PCR method, we inserted 6 amino acids into subsite -7 of CGTase. The mutant CGTase gene was ligated with pET-20b (+) and expressed in Escherichia coli BL21 (DE3). The extracellular recombinant enzyme was used to transform soluble starch into cyclodextrins (CDs). HPLC analysis results show that, compared to wild CGTase, the gamma-CDs produced by mutant enzyme decreased from 76.0% to 12.5%, whereas the ratio of alpha- and beta-CDs increased from 8.7% and 15.2% to 37.5% and 50%. The possible mechanism was that, compared to alpha-, beta-CGTase, wild gamma-CGTase lacks 6 amino acids in its subsite -7. This conformation provided more space for glucose combination and was thus advantageous for forming gamma-CD. When the 6 amino acids were inserted into the subsite -7 of wild gamma-CGTase, the space to bind with glucose reduced and consequently resulted in less gamma-CD production.
Bacillus ; enzymology ; genetics ; Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; biosynthesis ; genetics ; Mutant Proteins ; biosynthesis ; genetics ; Recombinant Proteins ; biosynthesis ; genetics

We studied the mutation effect of subsites -3(Lys47), -7(146-152), and cyclization center (Tyr195) in active domain on product specificity of alpha-cyclodextrin glucanotransferase (alpha-CGTase) from Paenibacillus macerans sp. 602-1. The Lys47 was replaced by Thr47 and Tyr195 by Ile195, and the amino acids from 146 to 152 were replaced by Ile (named as delta6). All these mutant alpha-CGTases were actively expressed in E. coli BL21. Compared with the wild-type alpha-CGTase, the starch-degrading activities of all the mutant enzymes were declined. For mutant Y195I, the percentage of alpha-CD was decreased from 68% to 30%, and beta-CD was raised from 22.2% to 33.3%. Interestingly, gamma-CD was increased from 8.9% to 36.7% and became the main product, while the actual yield was increased from 0.4 g/L to 1.1 g/L. Mutant K47T and delta6 still produced alpha-CD as main product though the percentage of beta- and gamma-CD increased. Purified Y195I CGTase showed similar optimum temperature with the wild-type alpha-CGTase, but its optimum pH shifted from 5.0 to 6.0 with better pH stability. In summary, mutant Y195I CGTase has the potential to produce gamma-CD as the main product.
Escherichia coli ; genetics ; metabolism ; Glucosyltransferases ; genetics ; metabolism ; Mutant Proteins ; genetics ; metabolism ; Mutation ; Paenibacillus ; enzymology ; Recombinant Proteins ; genetics ; gamma-Cyclodextrins ; metabolism

With the development of high gravity brewing, yeast cells are exposed to multiple brewing-associated stresses, such as increased osmotic pressure, enhanced alcohol concentration and nutritional imbalance. These will speed up yeast autolysis, which seriously influence beer flavor and quality. To increase yeast anti-autolytic ability, FKS1 overexpression strain was constructed by 18S rDNA. The concentration of β-1,3-glucan of overexpression strain was 62% higher than that of wild type strain. Meantime, FKS1 overexpression strain increased anti-stress ability at 8% ethanol, 0.4 mol/L NaCl and starvation stress. Under simulated autolysis, FKS1 showed good anti-autolytic ability by slower autolysis. These results confirms the potential of FKS1 overexpression to tackle yeast autolysis in high-gravity brewing.
Autolysis ; Beer ; Echinocandins ; genetics ; Glucosyltransferases ; genetics ; Hypergravity ; Membrane Proteins ; genetics ; Saccharomyces cerevisiae ; cytology ; Saccharomyces cerevisiae Proteins ; genetics

Trehalose, a compatible solute, is widely used in food, cosmetics, pharmaceutical products and organ transplantation. Nowadays, trehalose is mostly produced by enzymatic synthesis with many secondary products and lowpurity. In this study, high amount of trehalose was produced by recombinant E. ccli fermentation. First, a bifunctional trehalose gene TPSP was amplified from genome of C. hutchinscoii. Second, an expression vector pTac-HisA containing TPSP was constructed and transformed into the host E. coli. Expression of this bifunctional enzyme-TPSP converted glucose to trehalose. The result suggested that TPSP from C. hutchinsonji has been successfully expressed in E. ccoi. High amount of extracellular trehalose generated from glucose by whole-cell catalysis and After optimization, the production of trehalose in shake flasks was improved to 1.2 g/L and the relative conversion rate reached 21%. The production in bioreactor reached 13.3 g/L and the relative conversion rate reached 48.6%. It is the first time to realize the functional expression of the bifunctional enzyme-TPSP of C. hutchinsonii in E. coli and achieved the conversion form glucose to trehalose. This study laid a foundation for industrial large-scale production of trehalose.
Bioreactors ; Catalysis ; Escherichia coli ; genetics ; Glucose ; Glucosyltransferases ; Industrial Microbiology ; Organisms, Genetically Modified ; Trehalose ; biosynthesis

The lignan glycosyltransferase UGT236(belonging to the UGT71 B family) from Isatis indigotica can catalyze the production of phloridzin from phloretin in vitro. UGT236 shares high identity with P2'GT from apple. In this study, the recombinant plasmid pET28 a-MBP-UGT236 was transferred into Escherichia coli Rosetta(DE3) cells and induced by isopropyl-β-D-thiogalactoside(IPTG). The purified UGT236 protein was used for enzymatic characterization with phloretin as substrate. The results showed that UGT236 had the optimal reaction temperature of 40 ℃ and the optimal pH 8(Na_2HPO_4-NaH_2PO_4 system). The UGT236 activity was inhibited by Ni~(2+) and Al~(3+), enhanced by Fe~(2+), Co~(2+), and Mn~(2+), and did not affected by Mg~(2+), Ca~(2+), Li~+, Na~+, or K~+. The K_m, K_(cat), and K_(cat)/K_m of phloretin were 61.03 μmol·L~(-1), 0.01 s~(-1), and 157.11 mol~(-1)·s~(-1)·L, and those of UDPG were 183.6 μmol·L~(-1), 0.01 s~(-1), and 51.91 mol~(-1)·s~(-1)·L, respectively. The possible active sites were predicted by homologous modeling and molecular docking. By mutagenisis and catalytic activity detection, three key active sites, Glu391, His15, and Thr141, were identified, while Phe146 was related to product diversity. In summary, we found that the lignan glycosyltransferase UGT236 from I.indigotica could catalyze the reaction of phloretin into phloridzin. Several key amino acid residues were identified by structure prediction, molecular docking, and site-mutagenesis, which provided a basis for studying the specificity and diversity of phloretin glycoside products. This study can provide a reference for artificially producing glycosyltransferase elements with high efficiency and specific catalysis.
Glucosyltransferases/genetics* ; Glycosyltransferases/metabolism* ; Isatis ; Lignans/metabolism* ; Molecular Docking Simulation ; Phloretin/metabolism* ; Phlorhizin/metabolism*

The family of flavonoid 3-O-glucosyltransferase catalyzes the modification of anthocyanin from unstable-structure to stable-structure. In this study,based on homology cloning and transcriptome library,we isolated the full-length c DNA of UDP-glucose: flavonoid 3-O-glucosyltransferase( named SmUF3GT) from the flower tissues of S. miltiorrhiza. This gene was consisted of 1 353 bp open reading frames( ORF) encoding 450 amino acids. And the SmUF3GT protein was performed for the bioinformatic analysis. Our results showed that the protein was preliminary localized in the Golgi and peroxisome of cytosol,as well as plasma membrane and cell nuclear.QRT-PCR analyses indicated that SmUF3GT expressed differently in all tissues and organs but roots of S. miltiorrhiza and S. miltiorrhiza f.alba. During floral development,the expression of SmUF3GT showed a trend of rising fist and then down in purple-flower Danshen,whereas decreasing sharply fist and then slowly in white-flower Danshen. The present study provides basic information for further research on the network of synthesis and accumulation of flavonoids in S.miltiorrhiza.
Cloning, Molecular ; Flowers ; enzymology ; Gene Expression Regulation, Plant ; Glucosyltransferases ; genetics ; Open Reading Frames ; Plant Proteins ; genetics ; Salvia miltiorrhiza ; enzymology ; genetics

In plants, UDP-L-rhamnose is one of the major components of cell wall skeleton. Rhamnose synthase plays a key role in rhamnose synthesis which converts UDP-D-glucose into UDP-L-rhamnose in plants. In this study, we isolated the 1058 bp promoter region of the rhamnose synthase gene AtRHM1 from Arabidopsis genome by PCR, and created a series of deletions of AtRHM1 promoter ranging from -931 bp to +127 bp. The full length of the promoter and its deletion derivatives fused with GUS reporter gene were introduced into wild-type Arabidopsis by Agrobacterium-mediated transformation respectively. The GUS staining and GUS enzymatic activity assay showed that the expression of AtRHM1 is induced at transcriptional level by glucose and the regulatory elements involved in the glucose response are located in the region of -931 bp - -752 bp which contains three G-box motifs.
Arabidopsis ; genetics ; Arabidopsis Proteins ; genetics ; Glucosyltransferases ; genetics ; Plants, Genetically Modified ; genetics ; Promoter Regions, Genetic ; Uridine Diphosphate Glucose ; genetics ; metabolism ; Uridine Diphosphate Sugars ; genetics ; metabolism

Genetic modification of barley variety can be an efficient way to improve beer quality. The objective of this study was to understand the effect of trxS gene on hydrolases activities in transgenic and non-transgenic barley seeds. The results showed that alpha-amylase, free beta-amylase and limit dextrinase activity were increased in transgenic seeds in comparison with non-transgenic seeds. Sulfhydryl content of protein in transgenic seeds was also higher than that in non-transgenic seeds, suggesting that trxS gene could express in barley seeds, which opens a new way for breeding new barley varieties to improve beer quality.
Germination ; genetics ; Glucosyltransferases ; metabolism ; Hordeum ; enzymology ; genetics ; Plants, Genetically Modified ; enzymology ; genetics ; Seeds ; enzymology ; genetics ; Sulfhydryl Compounds ; metabolism ; Thioredoxins ; genetics ; alpha-Amylases ; metabolism ; beta-Amylase ; metabolism