Disclosed herein are glucosyltransferases with modified amino acid sequences. Such engineered enzymes exhibit improved alpha-glucan product yields and/or lower leucrose yields, for example. Further disclosed are reactions and methods in which engineered glucosyltransferases are used to produce alpha-glucan.

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of fermentation of metabolically engineered host cells. The present invention describes a method of making sialylated oligosaccharide by fermentation with a genetically modified cell, as well as to the genetically modified cell used in the method. The genetically modified cell comprises at least one nucleic acid sequence coding for an enzyme involved in sialylated oligosaccharide synthesis and at least one nucleic acid expressing a membrane protein.

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of fermentation of metabolically engineered host cells. The present invention describes a method of making sialylated oligosaccharide by fermentation with a genetically modified cell, as well as to the genetically modified cell used in the method. The genetically modified cell comprises at least one nucleic acid sequence coding for an enzyme involved in sialylated oligosaccharide synthesis and at least one nucleic acid expressing a membrane protein.

The disclosure discloses a method for efficient biosynthesis of Reb D by glycosyltransferase, belonging to the field of biocatalytic synthesis. According to the disclosure, a glycosyltransferase having an activity to catalyze synthesis of Reb D from Reb A is obtained, and a mutant YojK-I241T/G327N with high catalytic activity is obtained through directed evolution. The glycosyltransferase mutant YojK-I241T/G327N and a sucrose synthase AtSuSy derived from Arabidopsis thaliana are used for constructing a coupling reaction to realize efficient catalytic synthesis of Reb D with Reb A as a substrate. The reaction is carried out by using 19.32 g/L (20 mmol/L) of Reb A as the substrate for 15 h to efficiently synthesize 20.59 g/L of Reb D, and the yield of Reb D reaches 91.29%, which provides an efficient and green new pathway for production of Reb D.

The present invention relates to a group of glycosyltransferase, and an application thereof. Specifically, provided is using glycosyltransferase GT29-32, GT29-33, GT29-34, GT29-4, GT29-5, GT29-7, GT29-9, GT29-11, GT29-13, GT29-17, GT29-18, GT29-19, GT29-20, GT29-21, GT29-22, GT29-23, GT29-24, GT29-25, GT29-36, GT29-37, GT29-42, GT29-43, GT29-45, GT29-46, PNUGT29-1, PNUGT29-2, PNUGT29-3, PNUGT29-4, PNUGT29-5, PNUGT29-6, PNUGT29-7, PNUGT29-8, PNUGT29-9, PNUGT29-14, and PNUGT29-15, as well as derived polypeptides thereof to catalyze the first glycosyl at position C-20, the first glycosyl at position C-6, and the first glycosyl at position C-3 of a tetracyclic triterpene compound substrate to elongate a carbohydrate chain, thereby obtaining a catalytic reaction of ginsenoside products such as ginsenoside Rg3, ginsenoside Rd, ginsenoside Rb1, ginsenoside Rb3, saponin DMGG, saponin DMGX, gypenoside LXXV, gypenoside XVII, gypenoside XIII, gypenoside IX, notoginsenoside U, and notoginsenoside R1, notoginsenoside R2, notoginsenoside R3, 3-O-β-(D-xylopyranosyl)-β-(D-glucopyranosyl)-PPD, 3-O-β-(D-xylopyranosyl)-β-(D-glucopyranosyl)-CK, 20-O-Glucosylginsenoside Rf, and Ginsenoside F3. Glycosyltransferase in the present invention can further be applied to construction of artificially synthesized ginsenoside, novel ginsenoside, and derivatives thereof.

The present invention relates to a group of glycosyltransferase, and an application thereof. Specifically, provided is using glycosyltransferase GT29-32, GT29-33, GT29-34, GT29-4, GT29-5, GT29-7, GT29-9, GT29-11, GT29-13, GT29-17, GT29-18, GT29-19, GT29-20, GT29-21, GT29-22, GT29-23, GT29-24, GT29-25, GT29-36, GT29-37, GT29-42, GT29-43, GT29-45, GT29-46, PNUGT29-1, PNUGT29-2, PNUGT29-3, PNUGT29-4, PNUGT29-5, PNUGT29-6, PNUGT29-7, PNUGT29-8, PNUGT29-9, PNUGT29-14, and PNUGT29-15, as well as derived polypeptides thereof to catalyze the first glycosyl at position C-20, the first glycosyl at position C-6, and the first glycosyl at position C-3 of a tetracyclic triterpene compound substrate to elongate a carbohydrate chain, thereby obtaining a catalytic reaction of ginsenoside products such as ginsenoside Rg3, ginsenoside Rd, ginsenoside Rb1, ginsenoside Rb3, saponin DMGG, saponin DMGX, gypenoside LXXV, gypenoside XVII, gypenoside XIII, gypenoside IX, notoginsenoside U, and notoginsenoside R1, notoginsenoside R2, notoginsenoside R3, 3-O-β-(D-xylopyranosyl)-β-(D-glucopyranosyl)-PPD, 3-O-β-(D-xylopyranosyl)-β-(D-glucopyranosyl)-CK, 20-O-Glucosylginsenoside Rf, and Ginsenoside F3. Glycosyltransferase in the present invention can further be applied to construction of artificially synthesized ginsenoside, novel ginsenoside, and derivatives thereof.

Methods and compositions for modifying glycans (e.g., glycans expressed on the surface of live cells or cell particles) are provided herein.

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of fermentation of metabolically engineered microorganisms. The present invention describes engineered microorganisms able to synthesize sialylated compounds via an intracellular biosynthesis route. These microorganisms can dephosphorylate N-acetylglucosamine-6-phosphate to N-acetylglucosamine and convert the N-acetylglucosamine to N-acetylmannosamine. These microorganisms also have the ability to convert N-acetylmannosamine to N-acetyl-neuraminate. Furthermore, the present invention provides a method for the large scale in vivo synthesis of sialylated compounds, by culturing a microorganism in a culture medium, optionally comprising an exogenous precursor such as, but not limited to lactose, lactoNbiose, N-acetyllactosamine and/or an aglycon, wherein said microorganism intracellularly dephosphorylates N-acetylglucosamine-6-phosphate to N-acetylglucosamine, converts N-acetylglucosamine to N-acetylmannosamine and convert the latter further to N-acetyl-neuraminate.

The present invention is in the technical field of synthetic biology and metabolic engineering. More particularly, the present invention is in the technical field of fermentation of metabolically engineered microorganisms. The present invention describes engineered microorganisms able to synthesize sialylated compounds via an intracellular biosynthesis route. These microorganisms can dephosphorylate N-acetylglucosamine-6-phosphate to N-acetylglucosamine and convert the N-acetylglucosamine to N-acetylmannosamine. These microorganisms also have the ability to convert N-acetylmannosamine to N-acetyl-neuraminate. Furthermore, the present invention provides a method for the large scale in vivo synthesis of sialylated compounds, by culturing a microorganism in a culture medium, optionally comprising an exogenous precursor such as, but not limited to lactose, lactoNbiose, N-acetyllactosamine and/or an aglycon, wherein said microorganism intracellularly dephosphorylates N-acetylglucosamine-6-phosphate to N-acetylglucosamine, converts N-acetylglucosamine to N-acetylmannosamine and convert the latter further to N-acetyl-neuraminate.

This disclosure is in the technical field of synthetic biology and metabolic engineering. The disclosure provides engineered viable bacteria having a reduced or abolished synthesis of poly-N-acetyl-glucosamine (PNAG), Enterobacterial Common Antigen (ECA), cellulose, colanic acid, core oligosaccharides, Osmoregulated Periplasmic Glucans and Glucosylglycerol (O), glycan, and trebalose. The disclosure further provides methods for the production of bioproduct by the viable bacteria and uses thereof. Furthermore, the disclosure is in the technical field of fermentation of metabolically engineered microorganisms producing bioproduct.