Deoxy and amino sugars are often constituents of secondary metabolites of clinical importance such as polyketide and glycopeptide antibiotics.
The emergence of antibiotic resistance has created an urgent need for novel antibiotics active against resistant bacterial strains. Altering the composition of sugar appendages in glycoconjugates holds promise for creating new products with novel biological activities. Significant progress has been made via genetic and biochemical methods to develop effective glycosylation strategies in vivo, however yields are generally low, product analysis is difficult and the production of new glycosylated antimicrobial agents in vivo is limited by inhibition of cell growth or death.
The in vitro glycosylation using isolated glycosyltransferases could be a promising solution to overcome this hurdle.
The aims of this research project are:
(i) identification and characterization of the N-acetylglucosamine deacetylase involved in the biosynthesis of the glycopeptide antibiotic teicop lanin;
(ii) cloning and characterisation of the mannosyltransferase involved in the biosynthesis of teicoplanin;
(iii) determination of the order of glycosylation events leading to the maturation of teicoplanin;
(iv) in vitro synthesis of novel vancomycin/ teicoplanin glycopeptides.
The enzymes will be obtained by PCR amplification of genes from the Actinoplanes teichomyceticus teicoplanin producer strain and following expression of cloned genes in E. coli.
Upon purification the enzymes will be used in vitro assays to study their activity towards their natural and non-natural substrates and to generate novel glycopeptides.
The purified enzymes will also be subjected to protein-protein interaction studies and crystallisation in order to understand the structural biology of these systems.
This work will provide valuable information about the final steps of teicoplanin biosynthesis and pave the way to the in vitro generation of novel glycosylated antibiotics.
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