Recent advances in synthesis of bacterial rare sugar building blocks and their applications

Abstract

Covering: 1964 to 2013. Bacteria have unusual glycans on their surfaces which distinguish them from the host cells. These unique structures offer avenues for targeting bacteria with specific therapeutics and vaccine. However, these rare sugars are not accessible in acceptable purity and amounts by isolation from natural sources. Thus, procurement of orthogonally protected rare sugar building blocks through efficient chemical synthesis is regarded as a crucial step towards the development of glycoconjugate vaccines. This Highlight focuses on recent advances in the synthesis of the bacterial deoxy amino hexopyranoside building blocks and their application in constructing various biologically important bacterial O-glycans.

Extending the Scope of GTFR Glucosylation Reactions with Tosylated Substrates for Rare Sugars Synthesis

“…Decoration of the acceptor glucose with p ‐toluenesulfonyl groups in the 2‐, 3‐, and 6‐positions allowed the regioselectivity of the transglucosylation reaction to be controlled. The synthesized nigerose and isomaltose derivatives equipped with p ‐toluenesulfonyl groups are ideal functional building blocks for follow‐up reactions by S N 2 substitutions with different nucleophiles, that is, thioacetate, azides, and hydroxylates, and for the synthesis of bacterial rare‐sugar building blocks . In addition, the docking studies provided a plausible model for putative binding modes of the acceptors that might be responsible for the strict regioselectivity of the enzymatic reactions.…”

Metabolic glycoengineering bacteria for therapeutic, recombinant protein, and metabolite production applications

“…A recent review by Emmadi and Kulkarni has highlighted the chemical synthesis of particularly fascinating and extremely rare monosaccharides used by certain species of bacteria [100]. For example, 2-acetamindo-4-amino-2,4,6-trideoxy-D-galactose (AAT, Fig.…”

Biosynthesis of amino deoxy-sugar-conjugated flavonol glycosides by engineered Escherichia coli

“…Thus, exchanging the microbial glycone part with an aglycone from plant-derived secondary metabolites is an interesting approach for the generation of novel biologically potent compounds. Several approaches, such as (i) chemical syntheses [6,7], (ii) chemo-enzymatic approaches [8], (iii) enzymatic syntheses [9], and (iv) combinatorial biosynthesis [10,11] using microbial cells, are being used to conjugate different kinds of sugar units to natural products. Chemical synthesis of glycosides of plant secondary metabolites requires multiple steps and process is not eco-friendly whereas chemo-enzymatic and enzymatic syntheses need expensive cofactors as well as sugar donors along with purified enzymes.…”