Assembly of chimeric glycosyltransferases for directing biosynthesis of natural products

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This project seeks to combine the efforts of two established research teams in Cambridge to solve a major outstanding problem in chemistry and biochemistry: how to use protein engineering to generate novel glycosylated compounds that may have important biological activities. A significant fraction of drugs currently used in the clinic, especially anti-infectives such as erythromycins or vancomycins, are natural products isolated from soil bacteria, or derivatives of them. The unusual sugars they contain have been shown to be vital for biological activity. Enzymic modification of natural products is an attractive option to generate new compounds and decorating compounds with different sugars is particularly appealing. One major class of glycosyltransferases (GTs), the enzymes responsible for transferring a sugar from the donor nucleotide diphosphate (NDP) sugar to the acceptor molecule, is known to be composed of two domains. One binds the NDP-sugar donor and the other the acceptor molecule. Our preliminary studies have shown that by cutting and pasting domains from different GTs, hybrid enzymes can be constructed that remain highly active and have the respective donor and acceptor specificity of the parent GTs from which they were derived. This finding has led to the synthesis of several novel vancomycin analogues. These proof of principle experiments pave the way for making a wide range of hybrid GTs from over 19,000 known parent proteins to provide a toolbox of catalysts for accessing novel compounds. Constructing and exploiting these hybrid enzymes will require diverse experimental approaches from carrying out the synthesis of the novel compounds in a test tube with the purified enzymes to genetic manipulation of the genes inside the bacterial cells targetting novel natural products. Success in this project would deliver broad potential benefits to the pharmaceutical industry.