Understanding and manipulating glycopeptide pathways: the example of the dalbavancin precursor A40926

Glycopeptide antibiotics represent an important class of microbial compounds produced by several genera of actinomycetes. The emergence of resistance to glycopeptides among enterococci and staphylococci has prompted the search for second-generation drugs of this class and semi-synthetic derivatives are currently under clinical trials. Dalbavancin is obtained by chemical modification of the natural glycopeptide A40926, produced by a Nonomuraea sp. Recently, there has been considerable progress in the elucidation of biosynthesis of glycopeptide antibiotics; several gene clusters have been characterized, thus providing an understanding of the biosynthesis of these chemically complex molecules. Furthermore, such investigations have yielded the first glycopeptide derivatives produced by genetic or enzymatic intervention. We have isolated and characterized the dbv clusters, involved in the formation of the glycopeptides A40926. The development of a gene-transfer system for Nonomuraea sp. has allowed the manipulation of the A40926 pathway. New derivatives were obtained by inactivating selected dbv genes. In addition, our data suggest differences in the biosynthetic routes for heptapeptide formation between the vancomycin and the teicoplanin families of glycopeptides.