Chapter 18. Molecular genetic approaches to analyze glycopeptide biosynthesis.

The glycopeptide antibiotics vancomycin and teicoplanin are used in the hospital as drugs of last resort to combat resistant Gram-positive pathogens, in particular methicillin-resistant Staphylococcus aureus. All glycopeptides consist of a heptapeptide backbone in which the aromatic residues are connected to form a rigid cup-shaped structure required to stably interact with the D-Ala-D-Ala terminus of bacterial cell wall precursors. Structural diversity is generated by variations in the composition of the backbone, preferably at amino acid positions 1 and 3, and by different glycosylation, methylation, and chlorination patterns. The identification of several glycopeptide biosynthesis gene clusters, the development of genetic techniques to manipulate at least some of the producing actinomycetes, and subsequent molecular analysis enabled the elucidation of their biosynthetic pathways. This led to biochemical methods being combined with molecular genetic techniques and analytical chemistry. Knowledge of the biosynthesis made it possible to apply different approaches for the generation of novel glycopeptide derivatives by mutasynthesis, precursor-directed biosynthesis, and genetic engineering.