1008 results about "Transferase" patented technology

The invention discloses a glycosyl transferase mutant and an application of the glycosyl transferase mutant in synthesis of rebaudioside. According to the invention, single-point mutation and multi-point mutation are carried out on the basis of a glycosyl transferase amino acid sequence as shown in SEQ ID NO: 1, and a mutant with improved catalytic activity is obtained. The catalytic activity, the substrate specificity and / or the substrate specificity of the glycosyl transferase mutant are / is changed, and the catalytic activity of enzyme to a specific substrate can be remarkably improved by mutation at a specific site. And carrying out induced expression and protein purification on the obtained mutation sequence to obtain the mutant enzyme. The mutant enzyme is used as a catalyst, and UDPG is used as a glycosyl donor, so that the catalytic reaction efficiency of substrates such as stevioside ST, rebaudioside A (RebA) and rebaudioside D (RebD) can be obviously improved. According to the glycosyl transferase UGT76G1 mutant constructed by the research, the catalytic activity of the glycosyl transferase UGT76G1 mutant is improved, and efficient production of rebaudioside M is realized by optimizing a reaction system.

The invention relates to the technical field of biology, in particular to a beta-1, 4-galactosyl transferase mutant and a method for biologically synthesizing lactose-N-neotetraose by using the beta-1, 4-galactosyl transferase mutant. The invention discloses a protein, which is a protein HpgalT-186 or a protein HpgalT-146-186, a protein HpgalT-146 and a protein HpgalT-146. The protein HpgalT-186 is a protein obtained by mutating an amino acid residue at the 186th site of a wild type HpgalT; the protein HpgalT-146-186 is a protein obtained by carrying out mutation on an amino acid residue at the 186 site and an amino acid residue at the 146 site of wild type HpgalT. On the basis, a series of escherichia coli is constructed and optimized, the yield of the LNnT synthesized through shake flask fermentation of the finally obtained strain reaches 1.73-4.1 g / L, the highest yield in a 5L fermentation tank reaches 20-45.2 g / L, and efficient synthesis of the LNnT is achieved.

The invention discloses a protein palmitoyl transferase prediction method and system based on a multi-branch deep convolutional neural network, and belongs to the technical field of bioinformatics and artificial intelligence. The method comprises the following steps: S1, obtaining a to-be-detected protein sequence; s2, inputting the protein sequence into a pre-trained iPalmT model; and S3, judging whether the target protein is palmitoyl transferase or not according to a model output result. The iPalmT model comprises a coding module, two paths of parallel convolution branches, a feature fusion module and a classification module; and after the convolution layers of each convolution branch are stacked, an SE module is arranged and is used for channel weighting and feature re-calibration. The model extracts multi-level sequence features through convolution kernels of different scales, realizes high-precision prediction through feature fusion and a residual structure, can automatically learn multi-scale features from large-scale data, realizes end-to-end palmitoyl transferase recognition, and has high accuracy and good universality.

Glycosyltransferase UGT76G1 and UGT91C1 mutants and a method for catalytic synthesis of rebaudioside A, D, and M by using same, pertaining to the technical field of biocatalytic synthesis. The glycosyltransferase UGT76G1 mutant can effectively synthesize rebaudioside A using stevioside STV as a substrate. The glycosyltransferase UGT91C1 mutant is obtained by mutation screening of wild-type glycosyltransferase UGT91C1, has higher enzyme activity and catalytic rate, and can effectively synthesize rebaudioside D using rebaudioside A as a substrate. The glycosyltransferase UGT76G1 mutant can also be obtained by mutation and subsequent screening of glycosyltransferase UGT76G1, has higher catalytic activity, and can effectively synthesize rebaudioside M using rebaudioside D and UDPG as substrates.

The invention relates to a diacylglycerol acyltransferase mutant and application thereof in synthesis of triacylglycerol from saccharomyces cerevisiae, and belongs to the technical field of enzyme engineering. Diacylglycerol acyltransferase is a rate-limiting step of a synthetic route of saccharomyces cerevisiae triacylglycerol (TAG), and at present, a research on a DGA1 mutant for efficiently synthesizing TAG is lacked, and a research on the aspect of a DGA1 catalytic mechanism is also lacked. The DGA1 mutant capable of effectively improving TAG synthesis is obtained by screening in combination with a directed evolution technology, and a result shows that 282-site mutation of diacylglycerol acyltransferase can significantly increase the accumulation amount of TAG. Meanwhile, the catalytic mechanism of the DGA1 is preliminarily explored by combining protein structure prediction, molecular docking and molecular dynamics simulation, and a foundation is laid for deeply analyzing the catalytic mechanism of the DGA1. The recombinant saccharomyces cerevisiae is also constructed based on the mutant, so that the TAG synthesis is improved, and meanwhile, the relative proportion of C18: 1 in total fatty acids is remarkably increased.

The invention belongs to the technical field of microbial genetic engineering, and particularly relates to an alpha-2, 3-sialyltransferase mutant and application thereof. The a-2, 3-sialyltransferase mutants V175N, P198A, G173D, D174Q, F196K and A315H are obtained by performing site-specific mutagenesis on six amino acids in an a-2, 3-sialyltransferase amino acid sequence coded by a gene derived from Campylobacter jejuni (OH4384), the yield of 3 '-sialyllactose is remarkably increased by single-point mutagenesis of the V175N, the yield of 3'-sialyllactose is remarkably increased by single-point mutagenesis of the V175N, the yield of 3 '-sialyllactose is remarkably increased by single-point mutagenesis of the P198A, the G173D, the D174Q, the F196K and the A315H, the optimal recombinant microbial strain 3 '-SL-09 (V175N / P198A / D174Q) is obtained through combination of multiple mutation sites, the yield can reach 5.91 g / L, the bottleneck problem of low catalytic efficiency of sialyltransferase is effectively solved, and an enzyme element with excellent performance is provided for high-efficiency and low-cost biological manufacturing of 3'-SL.

The application discloses a specific palmitoyl transferase inhibitor and application thereof, and an active ingredient of the palmitoyl transferase inhibitor is 4-(3-(2-(trifluoromethyl)-9H-thioxanthene-9-ylidene)propyl)-1-piperazine ethanol or a salt thereof. Current palmitoylation inhibitors, 2-bromohexadecanoic acid (2-BP), cerulenin and tunicamycin can all inhibit protein palmitoylation in cells, but all are not selective. And the existing palmitoylation inhibitors are similar to endogenous fatty acids, and inevitably affect lipid metabolism in the body, which limits the clinical application. The application discloses, for the first time, the application of 4-(3-(2-(trifluoromethyl)-9H-thioxanthene-9-ylidene)propyl)-1-piperazine ethanol as a specific palmitoyl transferase inhibitor, and the palmitoyl transferase inhibitor is better in specificity and reversible in inhibition.

The present invention belongs to the field of biotechnology, and specifically relates to a GmSGT2 gene related to plant height and branch development, and a mutant thereof and the use thereof. A Glycine max mutant having fewer branches and decreased plant height is obtained by means of EMS mutagenesis, and a target gene thereof that is located by means of a map-based cloning technique is a GmSGT2 gene of Hedou 12. It is found through searching that the gene encodes soyasapogenol B glucuronide galactosyltransferase, and can galactosylate soyasapogenol B monoglucuronide, thereby affecting the plant height of Glycine max and reducing the branches of Glycine max. Therefore, the GmSGT2 mutant can be used for cultivating dwarf high-yield Glycine max varieties, and is of great significance in the breeding of ideal plant types of Glycine max and research on important agronomic traits of plants. The mutant has broad application prospects and great research value with regard to understanding the plant height and branch regulation mechanism of Glycine max and improving the process of Glycine max breeding; and can provide an excellent germplasm resource stock for regulating the close planting and high-yield breeding of Glycine max.

The present application relates to the technical field of biocatalysis and biosynthesis, and specifically discloses a natural blue pigment and a biosynthesis method therefor. The present application uses metabolically engineered bacteria to express indigoidine synthetase and phosphopantetheinyl transferase, to catalyze glutamine and N-acetylglutamine to biosynthesize a natural blue pigment N-acetylindigoidine, and deduces its molecular structure by means of mass spectrometry, nuclear magnetic resonance and other methods. The present application achieves catalytic synthesis of N-acetylindigoidine from glutamine and N-acetylglutamine in Escherichia coli, Corynebacterium glutamicum, Saccharomyces cerevisiae and Streptomyces. Compared with indigoidine, N-acetylindigoidine has a maximum absorption wavelength of 584 nm, possesses better color brightness, and has more stable coloration that is not easily faded, with a very broad application range and industrial production application prospects.

The invention provides a whey protein deep hydrolysate with low sensitization and an allergy relieving effect as well as a preparation method and application of the whey protein deep hydrolysate. According to the method, the alkaline protease, the neutral protease and the glutamyltransferase are sequentially used for carrying out first enzymolysis, second enzymolysis and third enzymolysis on the whey protein raw material, and the whey protein hydrolysate which is low in molecular weight, good in taste, good in digestion and absorption performance, low in sensitization and capable of effectively relieving allergic reaction of the organism is obtained.

The invention relates to the technical field of gene engineering, in particular to a glycosyl transferase mutant, a sucrose synthase mutant and application of the glycosyl transferase mutant and the sucrose synthase mutant in synthesis of rebaudioside M. Wild glycosyl transferase and wild sucrose synthase are modified according to a directed evolution theory to obtain a glycosyl transferase mutant and a sucrose synthase mutant. Rebaudioside M is obtained by catalyzing rebaudioside D through a glycosyl transferase mutant and sucrose synthase mutant co-expression strain, and the catalytic efficiency is superior to that of a wild enzyme. The rebaudioside M is obtained by completely catalyzing 110 g / L of rebaudioside D through the co-expression strain of the glycosyl transferase mutant and the sucrose synthase mutant, only 20 h is needed, the conversion rate reaches 97%, the yield of the rebaudioside M reaches 122 g / L, the raw material conversion rate and the yield of the rebaudioside M are effectively increased, and meanwhile the synthesis time is shortened.

The application discloses a galactosyltransferase mutant and application thereof in preparation of flavonoid compounds, and belongs to the technical field of enzymology. The application provides a UDP-galactosyltransferase mutant, which is obtained by site-directed mutation of one amino acid in the amino acid sequence of wild-type galactosyltransferase VcUFGT into alanine (A). The effects of a series of mutants H82A, V139A, G141A, P186A, N245A, V282A and S307A are verified in the examples, the mutants can perform enzyme catalysis reaction with quercetin and UDP-galactoside as substrates, and generate flavonoid compound hyperoside, and the specific enzyme activity of the mutants is more than 1.5 times that of the wild type, thereby providing an effective application basis for biosynthesis of flavonoid compounds.

The present application relates to the technical field of biocatalysis and biosynthesis, and specifically discloses a blue pigment and a biosynthesis method thereof. In the present application, an indigoidine synthetase and a 4′-phosphopantetheinyl transferase are expressed by a metabolically engineered strain to catalyze the biosynthesis of the blue pigment N-acetyl-indigoidine from glutamine and N-acetylglutamine, and a molecular structure of the blue pigment is inferred by mass spectrometry, nuclear magnetic resonance spectroscopy, etc. The present application achieves the catalytic synthesis of N-acetyl-indigoidine from glutamine and N-acetylglutamine in Escherichia coli (E. coli), Corynebacterium glutamicum (C. glutamicum), Saccharomyces cerevisiae (S. cerevisiae), and Streptomyces. Compared with indigoidine, N-acetyl-indigoidine has a maximum absorption wavelength of 584 nm, and a stable color having high brightness that is not easy to fade. Thus, the blue pigment shows an extensive application range and a promising industrial production prospect.

According to the invention, a glycosyl transferase mutant derived from Bacillus licheniformis ZSP01 is used as a research object, AlphaFold 2 is used for constructing a three-dimensional structure of a protein, then technologies such as molecular docking and molecular dynamics simulation are used for analyzing amino acids far away from a catalytic center in glycosyl transferase, site-directed mutagenesis is carried out on the amino acids, and the glycosyl transferase is obtained. The activity of the mutant for catalytically synthesizing the icariside D2 glycosyltransferase is improved.

The invention provides a method for producing glycosyltransferase or sucrose synthase by fermenting recombinant escherichia coli, and belongs to the technical field of biological fermentation. According to the fermentation method provided by the invention, a three-stage material supplementing control fermentation strategy is adopted, namely after fermentation is carried out for 5 hours, material supplementing operation is started, the material supplementing speed is 6.24-7.20 g / L / h, fermentation is carried out for 8-10 hours, the material supplementing speed is reduced to 4.80 g / L / h, the temperature is reduced to 25 DEG C, and induction is carried out; then maintaining the material supplementing speed until the fermentation OD600 is 65-75, and then reducing the material supplementing speed to 3.84-4.80 g / L / h until the OD600 is not obviously increased any more; the material supplementing mode has remarkable advantages in the aspects of improving fermentation OD600 and fermentation enzyme activity, shortening the fermentation period, reducing the cost and the like.

The invention belongs to the technical field of biology, and particularly relates to application of serine in relieving heat stress of pleurotus ostreatus and a method. Under the heat stress condition, exogenous serine supply promotes pleurotus ostreatus hypha to recover growth, and the activity of antioxidant enzyme, the yield of sporocarp and the yield of nutrient substances are improved; when the activity of the PHGDH enzyme is inhibited, the serine synthesis is reduced; the hypha growth can be promoted by overexpressing the phgdh, and the enzymatic activity of the PHGDH can be improved; when acetyltransferases HAT, NAT1, NAT2 and NAT3 act on a K394 site of the PHGDH, the enzyme activity of the PHGDH can be improved, endogenous serine metabolism is activated to respond to heat stress, it is indicated that PHGDH-mediated serine metabolism plays an important role in corresponding heat stress of the pleurotus ostreatus, and the invention discloses a mechanism for improving heat resistance of the pleurotus ostreatus through the PHGDH-mediated serine metabolism. And a foundation can be laid for breeding high-temperature-resistant pleurotus ostreatus dominant strains.

The invention relates to a diacylglycerol acyltransferase capable of synthesizing triglyceride as well as a coding gene and application of the diacylglycerol acyltransferase, and belongs to the field of enzymology, the nucleotide sequence of the gene for coding the diacylglycerol acyltransferase is as shown in SEQ ID NO.1, and the amino acid sequence of the diacylglycerol acyltransferase is as shown in SEQ ID NO.2. The invention also provides a recombinant plasmid and a recombinant engineering bacterium containing the gene of the enzyme. Diglyceride and an acyl donor are used as substrates, and triglyceride is catalytically synthesized through an acyl transfer reaction by using the enzyme. The invention provides an efficient tool for realizing enzymatic biosynthesis and large-scale production of natural triglyceride.

The invention belongs to the technical field of synthetic biology, and particularly relates to recombinant escherichia coli for efficiently producing O-acetyl-L-homoserine as well as a construction method and application of the recombinant escherichia coli. According to the invention, CRISPR-Cas9 gene editing is combined with metabolic modification, so as to precisely integrate OAH biosynthesis key nodes: introducing and overexpressing a mutant metX gene at a genome pseudogene site to enhance the expression of homoserine acetyltransferase, knocking out byproducts such as poxB and mgsA to synthesize genes, and carrying out high-yield synthesis of OAH. Corynebacterium glutamicum thrA (anti-feedback inhibition), aspB and bacillus subtilis acsA-acuA genes (construction of an acetic acid switch) are introduced, gene expression of gltA, tpiA and the like is optimized to increase supply of precursors such as acetyl CoA and the like, and finally a stable strain without plasmids, antibiotics and inducers is obtained. The production cost is effectively reduced, and the method has the advantage of high genetic stability and shows a good application prospect in OAH industrial production.

According to the present invention, glycosyl transferase UGTBL1 derived from Bacillus licheniformis ZSP01 is adopted as a research object, AlphaFold 2 is adopted to carry out modeling, molecular docking, molecular dynamics simulation and other technologies, amino acids in an active pocket region of glycosyl transferase are analyzed, site-directed mutagenesis is performed on the amino acids to obtain a series of glycosyl transferase mutants, and salidroside can be highly selectively catalyzed and synthesized.

The invention relates to an application of a histone H3K18 lactic acid modification related target in preparation of a medicine for preventing or treating atherosclerosis. The invention belongs to the field of biological medicine, and discloses histone acetyltransferase P300 and application of histone H3K18 lactylation (H3K18la) modification mediated by the histone acetyltransferase P300 as a new target spot for treating atherosclerosis (AS). Researches find that in the AS process, lactic acid accumulation in vascular smooth muscle cells (VSMCs) up-regulates H3K18la through P300 catalysis, and then the pathological phenotype of the VSMCs is induced, and plaque development is promoted. H3K18la can be reduced and the phenotype can be improved by inhibiting LDHA and MCT1 in vitro or knocking out a P300 gene; the P300 for in-vivo targeted inhibition of the VSMCs can significantly reduce the artery plaque. Therefore, the P300 and H3K18la inhibitors can be used for preparing the anti-atherosclerosis medicine.

The invention relates to the technical field of prebiotics preparation, and discloses a preparation method of prebiotics applied to reproduced areca catechu, and the preparation method comprises the following steps: carrying out enzyme catalysis reaction on sucrose by adopting fructosyl transferase to prepare fructo-oligosaccharide; according to the method, beta-galactosidase is adopted to carry out enzyme catalysis reaction on lactose, so that galactooligosaccharide is prepared; respectively carrying out decoloration, ion exchange, nanofiltration concentration and spray drying on the candy oligosaccharide and the galactooligosaccharide to obtain powder; the method comprises the following steps: mixing fructo-oligosaccharide powder and galactooligosaccharide powder according to a ratio, and uniformly distributing the mixture in a reproduced areca-nut matrix by adopting a spray-drying blending or low-temperature vacuum mixing mode to form a functional reproduced areca-nut product; according to the invention, low-temperature drying is carried out on the product after blending or vacuum mixing, so that the prebiotic areca nuts are released along with saliva in the chewing process, and are selectively utilized by bifidobacteria and lactic acid bacteria after entering the stomach and intestine, thereby achieving the purposes of regulating intestinal flora and improving the health-care function.

The utility model discloses automatic enzyme-linked immunoassay detection equipment which comprises a processing module and a washing liquid module, and the processing module comprises a pipetting module, a clamping jaw module and an operation processing area, the operation treatment area is provided with a reaction container, a cleaning position, a cleaning head matched with the cleaning position, an oscillation incubation area, a sample adding area, a consumable loading area, a reagent loading area and an enzyme immunoassay detection area, the cleaning head comprises a liquid injection needle and a liquid suction needle, and the pipetting module and the clamping jaw module can be driven to move along the operation treatment area. The pipetting module can transfer a sample liquid or a reagent to the reaction container, the clamping jaw module can move to the reaction container to perform cover opening and closing operation and can transfer the reaction container into a cleaning position, and the washing liquid module can be in fluid communication with the liquid injection needle and the liquid suction needle to complete cleaning of the reaction container. The detection equipment provided by the utility model can realize a series of full-automatic enzyme immunoassay detection such as sample transfer, reagent transfer, enzyme immunoassay reaction, cleaning and enzyme immunoassay detection.

The application belongs to the technical field of biotechnology and gene therapy, and particularly relates to application of SNIP1 protein as a target in preparation or screening of an antitumor drug. The application finds that the SNIP1 protein is a non-histone substrate of lysine methyltransferase KMT5A, which promotes breast cancer cell growth, invasion and lung metastasis through KMT5A-mediated K301 monomethylation; therefore, the SNIP1 protein can be used as a target for screening of an antitumor drug, and a drug obtained by screening and inhibiting methylation of the K301 site of the SNIP1 protein can be used for antitumor; and the application provides a polypeptide specifically combined with the K301 site of the SNIP1 protein, the polypeptide is combined with the K301 site of the SNIP1 protein, inhibits methylation of the SNIP1 protein, and finally can inhibit tumor growth, proliferation, invasion and metastasis, and can be used as a new targeted antitumor drug.

The invention discloses an engineered glycosyl transferase and application thereof in efficient preparation of triterpenoid saponin. The engineered glycosyl transferase is obtained by mutating serine at the 15th site of UGT74AC1 enzyme into alanine, mutating histidine at the 47th site into aspartic acid, mutating leucine at the 48th site into valine, mutating alanine at the 180th site into serine, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid, mutating histidine at the 180th site into aspartic acid The mutant is obtained by mutating serine at the 332 site into proline, phenylalanine at the 367 site into tryptophan and lysine at the 420 site into arginine. According to the invention, the glycosyl transferase with high catalytic activity is obtained by modifying an enzyme engineering technology, and good application of the glycosyl transferase in synthesis of triterpenoid saponin is realized. The glycosyl transferase disclosed by the invention can also be coupled with sucrose synthase, or coupled with N-acetylhexosamine kinase and N-acetylglucosamine-1-uridine phosphate transferase, and acetylglucosamine is used as a glycosyl donor, so that cascade production of triterpenoid saponin with lower cost and higher efficiency is realized.

The invention provides a recombinant O-succinyl-L-homoserine mercaptotransferase mutant, a coding gene thereof, a recombinant vector containing the coding gene of the mutant, a recombinant genetically engineered bacterium obtained by converting the recombinant vector, and application of the recombinant O-succinyl-L-homoserine mercaptotransferase mutant in preparation of L-methionine. The novel recombinant O-succinyl-L-homoserine mercaptotransferase mutant with high activity and high selectivity is used as a catalyst to be applied to catalysis of O-succinyl-L-homoserine for synthesis and preparation of L-methionine, a catalytic reaction system is optimized, the feed ratio and reaction conditions in the reaction are finely regulated and controlled, and the yield of L-methionine is increased. The recombinant O-succinyl-L-homoserine mercaptotransferase mutant has high enzyme activity under the optimal reaction condition, the catalytic efficiency is further improved, the purposes of reducing cost and improving efficiency are achieved, and the method has important significance in promoting industrial application of biological catalysis preparation of L-methionine.

The invention discloses arabinose glycosyl transferase PnUGT73B4 and application thereof to preparation of panax japonicus saponin IV, the amino acid sequence of the arabinose glycosyl transferase is shown as SEQ ID NO: 1, under the catalysis of the arabinose glycosyl transferase PnUGT73B4, UDP-arabinose is added to a glucuronic acid group on the C3 site of panax japonicus saponin IVa, and the panax japonicus saponin IV is generated; according to the method, the requirement for raw material plants can be reduced, agricultural land is saved, the product is single, preparation of the panax japonicus saponin IV is facilitated, the biosynthesis route of oleanane type triterpenoid saponin is analyzed, and a breakthrough solution is provided for biosynthesis of the panax japonicus saponin IV.

The invention belongs to the technical field of biology, and particularly relates to a construction method and application of a tobacco plant for expressing rare ginsenoside. According to the method, dammarendiol synthase DDS, cytochrome P450 CYP716A47 and glycosyl transferase UGTPg1 / UGTPg45 are added into tobacco, heterologous synthesis of rare ginsenosides CK and Rh2 is achieved, dependence on traditional ginseng cultivation extraction is avoided, and cost is remarkably reduced and efficiency is remarkably improved. The characteristics of short growth cycle and easy culture of tobacco are utilized to overcome the problems of low efficiency and low yield of traditional synthesis; positive transgenic tobacco leaves are dedifferentiated to form callus cells, so that materials are provided for large-scale fermentation, and an industrial production foundation is laid.

The present disclosure relates to bifunctional compounds, which find utility as modulators of Protein Arginine N-Methyl Transferase 5 (PRMT5) in MTAP deleted / low expressing cells. In particular, the present disclosure is directed to bifunctional compounds, which contain on one end a ligand which binds to an E3 ubiquitin ligase and on the other end a moiety which binds the PRMT5-MTA complex, such that the PRMT5 protein is placed in proximity to the ubiquitin ligase to effectuate ubiquitination, and therefore, degradation (and inhibition) of PRMT5 protein, as well as methods for their preparation and use. Specifically, the present invention describes compounds of Formula (I) and pharmaceutically acceptable salts, hydrates and solvates, as well as methods for their preparation and use

The invention belongs to the technical field of bioengineering, and particularly relates to a phosphorylcholine cytidyltransferase mutant and application thereof. On the basis of phosphorylcholine cytidyltransferase MsCCT001, any one or more of N194D, K91E, G98S, S148A and C156V are mutated respectively, a series of phosphorylcholine cytidyltransferase mutants are obtained through screening, and the obtained mutants have the advantages that in the reaction of catalyzing phosphorylcholine and cytidine triphosphate to generate citicoline, the yield of the obtained mutants is increased, and the yield of the obtained mutants is increased. The catalytic efficiency of the compound is 1.90-2.41 times that of initial phosphorylcholine cytidyltransferase, and a biological enzyme preparation with higher catalytic capacity is provided for preparing citicoline by a biological conversion method.

The invention belongs to the technical field of biology, and particularly relates to a genetically engineered bacterium capable of reducing by-products and improving yield of heparin precursors as well as a construction method and application of the genetically engineered bacterium. According to the technical scheme, acetic acid synthesis pathway genes ackA and poxB and lactic acid synthesis pathway genes ldhA are knocked out, and synthesis of acetic acid and lactic acid is blocked, so that more carbon metabolic flows enter heparin precursor synthesis pathways, the yield and conversion rate of heparin precursors are increased, and / or by-products are reduced. According to the invention, heparin precursor synthetases KfiA (UDP-GlcNAc glycosyl transferase), KfiC (UDP-GlcA glycosyl transferase) and KfiD (UDP-glucose dehydrogenase) are further enhanced, the expression of UDP-GlcA generated by UDP-Glc is catalyzed, and the yield and the conversion rate of the heparin precursor can be further improved and / or byproducts can be further reduced.