P1 Trisaccharide (Galα1,4Galβ1,4GlcNAc) Synthesis by Enzyme Glycosylation Reactions Using Recombinant Escherichia coli

Abstract

The frequency of Escherichia coli infection has lead to concerns over pathogenic bacteria in our food supply and a demand for therapeutics. Glycolipids on gut cells serve as receptors for the Shiga-like toxin produced by E. coli. Oligosaccharide moiety analogues of these glycolipids can compete with receptors for the toxin, thus acting as antibacterials. An enzymatic synthesis of the P1 trisaccharide (Gal␣1,4Gal␤1,4GlcNAc), one of the oligosaccharide analogues, was assessed in this study. In the proposed synthetic pathway, UDP-glucose was generated from sucrose with an Anabaena sp. sucrose synthase and then converted with an E. coli UDP-glucose 4-epimerase to UDP-galactose. Two molecules of galactose were linked to N-acetylglucosamine subsequently with a Helicobacter pylori ␤-l,4-galactosyltransferase and a Neisseria meningitidis ␣-1,4-galactosyltransferase to produce one molecule of P1 trisaccharide. The four enzymes were coexpressed in a single genetically engineered E. coli strain that was then permeabilized and used to catalyze the enzymatic reaction. P1 trisaccharide was accumulated up to 50 mM (5.4 g in a 200-ml reaction volume), with a 67% yield based on the consumption of N-acetylglucosamine. This study provides an efficient approach for the preparative-scale synthesis of P1 trisaccharide with recombinant bacteria.Recently, vaccines have been introduced to prevent illness from pathogenic Escherichia coli, yet there remains a need for therapeutics to treat acute infection (27). Unlike endogenous E. coli from our intestine, the pathogenic strain (O157:H7) has acquired a gene from Shigella which produces a toxic protein. This Shiga-like toxin binds to glycolipid receptors on cells of the gut wall and can ultimately lead to dysentery, hemorrhagic colitis, and sometimes life-threatening complications (32). The attachment of the microbial protein onto mammalian cells through surface carbohydrates initiates a successful infection (18). The Shiga-like toxin will also bind other carbohydrate derivatives, including globotriosylceramide (Gal␣1,4Gal␤1, 4Glc-ceramide) found on the cell surface (4,(24)(25)(26)44) and trisaccharide analogues, such as globotriose (Gal␣1,4Gal␤1, 4Glc) and the trisaccharide moiety of P1 antigen (Gal␣1, 4Gal␤1,4GlcNAc) (1). The mechanism of action for the proposed therapy involves preventing the toxin from binding to cell receptors by introducing these molecules to the site of infection. Instead of binding to cell receptors, the toxic peptides bind to the carbohydrate analogues and are removed from the body without causing harm. Of the three carbohydrate moieties mentioned above, P1 trisaccharide is the most effective therapeutic. Although synthesis remains a limiting factor, if available in large quantities these trisaccharides have considerable potential as antiadhesive agents in the treatment of pathogenic E. coli infections (17,36,37).Chemical syntheses of oligosaccharides have always been complicated by their structural complexity and have traditionally involved laborious protection p...

Benthic Nitrogen Loss in the Arabian Sea Off Pakistan

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Enzymatic synthesis of vancomycin derivatives using galactosyltransferase and sialyltransferase

“…9,10 Thus, Wang's group already showed that enzymatic synthesis of the P1 trisaccharide (Gala1,4Galb1,4GlcNAc), an oligosaccharide analogue, was assessed with H. pylori b1,4-GalT and Neisseria meningitides a1,4-GalT. 11 Those studies provide an efficient approach, including the substrate flexibility of b1,4-GalT, for the galactosylation of other molecules. In addition, the Pm0188 gene from P. multocida has been cloned, and a truncated protein (tPm0188Ph) was expressed in E. coli.…”

“…23 Enzymatic effect of b-1,4-GalT and a-2,3 Sia T in NeuAca2,3-Gal b-1,4 GlcNAc Protocols used to enzymatically synthesize Galb1,4-GlcNAc (4) and NeuAca2,3 Galb1,4-GlcNAc (5) using b1,4-GalT and a2,3-SiaT were performed as published elsewhere. 11,12,24 Compound 3 was tested in an enzymatic reaction with b1,4-GalT in an attempt to prolong the production of 4. The galactosylation reaction was performed with 50 mM HEPES, pH 7.6, 1.0 mM MnCl 2 , 40 mM 3, 20 mM UDP-Gal and 100 mM purified b1,4-GalT.…”

“…It was cloned nearly a decade ago and demonstrated that HP0826 has a highly efficient activity for the synthesis of trisaccharides (Gala1, 4Galb1, 4GlcNAc) with recombinant bacteria. [9][10][11] Another glycosyltransferase gene, Pm0188, which encodes multifunctional sialyl transferases (SiaTs), was cloned from Pasteurella multocida genomic strain Pm70 and four functions, such as a2,3-SiaT, a2,6-SiaT, sialidase and trans-sialidase, have been identified. 12 Especially, a2,3-SiaT can transfer a sialic acid (Sia) residue from CMP-Sia to galactosides to form a2,3 sialyl linkages efficiently at a wide range of pH values (pH 7.5-9.0).…”

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“…The values are given as s -1 . ** Hydrolytic activity using 2.6 mM X 3 . The values are given as s -1 .…”