ABSTRACT
Heparin and heparan sulfate are a class of glycosaminoglycans for clinical anticoagulation. Heparosan N-sulfate-glucuronate 5-epimerase (C5, EC 5.1.3.17) is a critical modifying enzyme in the synthesis of heparin and heparan sulfate, and catalyzes the inversion of carboxyl group at position 5 on D-glucuronic acid (D-GlcA) of N-sulfoheparosan to form L-iduronic acid (L-IdoA). In this study, the heparin C5 epimerase gene Glce from zebrafish was expressed and molecularly modified in Escherichia coli. After comparing three expression vectors of pET-20b (+), pET-28a (+) and pCold Ⅲ, C5 activity reached the highest ((1 873.61±5.42) U/L) with the vector pCold Ⅲ. Then we fused the solution-promoting label SET2 at the N-terminal for increasing the soluble expression of C5. As a result, the soluble protein expression was increased by 50% compared with the control, and the enzyme activity reached (2 409±6.43) U/L. Based on this, site-directed mutations near the substrate binding pocket were performed through rational design, the optimal mutant (V153R) enzyme activity and specific enzyme activity were (5 804±5.63) U/L and (145.1±2.33) U/mg, respectively 2.41-fold and 2.28-fold of the original enzyme. Modification and expression optimization of heparin C5 epimerase has laid the foundation for heparin enzymatic catalytic biosynthesis.
Subject(s)
Animals , Carbohydrate Epimerases , Chemistry , Genetics , Escherichia coli , Gene Expression , Heparin , Metabolism , Heparitin Sulfate , Metabolism , Iduronic Acid , Metabolism , Zebrafish Proteins , Chemistry , GeneticsABSTRACT
Sulfated compounds are widely present in cytoplasm, on cell surface, and in extracellular matrix. These compounds play important roles in cell development, differentiation, immune response, detoxication, and cell signal transduction. 3-Phosphoadenosine-5-phosphosulfate (PAPS) is the universal sulfate group donor for the biosynthesis of sulfated compounds. Up to now, the synthesis of PAPS is still too expensive for industrial applications. This review focuses on the recent progress of PAPS production and summaries the application of PAPS, particularly in the production of glucosinolate, heparin, condroitin sulfate, and oxamniquine production.
Subject(s)
Cell Differentiation , Chondroitin Sulfates , Phosphoadenosine Phosphosulfate , Metabolism , SulfatesABSTRACT
Heparin is a very important anticoagulant drug. Currently, heparin is mainly extracted from porcine mucosa. However, animal-derived heparin shows low anticoagulant activity due to the low proportion of the anticoagulant active unit, the GlcNS6S-GlcA-GlcNS6S3S-Ido2S-GlcNS6S pentasaccharide. In this study we proposed an enzymatic strategy to sulfate the animal-sourced heparin to increase the proportion of anticoagulant pentasaccharide and the anticoagulant activity. First, three sulfotransferases HS2ST, HS6ST, and HS3ST were expressed tentatively in Escherichia coli and Pichia pastoris. After measuring the sulfotransferase activity, we confirmed P. pastoris GS115 is the better host for sulfotransferases production. Then, the maltose binding protein (MBP) and thioredoxin (TrxA) were fused separately to the N-terminal of sulfotransferases to increase enzyme solubility. As a result, the yields of HS2ST and HS6ST were increased to (839±14) U/L and (792±23) U/L, respectively. Subsequent sulfation of the animal-sourced heparin with the recombinant HS2ST, HS6ST and HS3ST increased the anticoagulant activity from (76±2) IU/mg to (189±17) IU/mg.
Subject(s)
Animals , Escherichia coli , Heparin , Chemistry , Oligosaccharides , Chemistry , Pichia , Sulfotransferases , SwineABSTRACT
Heparosan is the start point for chemoenzymatic synthesis of heparin and it is of great significance to efficiently synthesize heparosan in microorganisms. The effects of overexpressing key enzyme genes of the UDP-glucuronic acid (UDP-GlcUA) pathway (pgcA, gtaB and tuaD) or the UDP-N-acetyl-glucosamine (UDP-GlcNAc) pathway (glmS, glmM and glmU) on the heparosan production and molecular mass were analyzed in the constructed heparosan-producing Bacillus subtilis ((1.71±0.08) g/L). On this basis, heparosan production was increased to (2.89±0.11) g/L with the molecular mass of (75.90±1.18) kDa through co-overexpressing the tuaD, gtaB, glmU, glmM and glmS genes in shake flask cultivation. In the 3 L fed-batch fermentation, heparosan production was improved to (7.25±0.36) g/L with the molecular mass of (46.66±2.71) kDa, providing the potential for heparosan industrial production.