This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Vancomycin and teicoplanin are glycopeptide antibiotics used clinically to treat many gram-positive bacterial infections, including methicillin resistant Staphylococcus aureus (MRSA). During their biosynthesis, each member of this family of antibiotics is functionalized by a unique set of finishing enzymes that includes glycosyl, acyl, methyl and sulfo- transferases. The discovery of new glycopeptide congeners has slowed in recent years as it has become increasingly difficult to identify new biodiversity from which novel molecules might be characterized. The vast majority of bacteria present in nature remain recalcitrant to culturing and therefore they represent a potentially novel source of small molecules. Although metabolites produced by these bacteria cannot be characterized using standard microbiological methods, it is possible to extract DNA directly from environmental samples and analyze this DNA for sequences that encode the biosynthesis of novel natural products. In a survey of DNA extracted from desert soil, we uncovered a biosynthetic gene cluster (the TEG gene cluster) that is predicted to encode the biosynthesis of the first polysulfated glycopeptide congeners. The TEG gene cluster contains three closely related sulfotransferases (Teg12, 13, and 14) that sulfate teicoplanin like glycopeptides at three unique sites, and in combination, they can be used to produce 7 different sulfation patterns. Over 150 different glycosylated, halogenated, and alkylated glycopeptide congeners have been characterized from cultured bacteria, yet only three sulfated congeners have been identified from studying these same microbes. The enzymatic synthesis of anionic glycopeptides could provide a facile means to access additional anionic congeners. High-resolution X-ray crystal structures of the TEG sulfotransferases should provide insight into how these enzymes might be engineered to generate additional anionic glycopeptides that could be evaluated against clinically relevant drug resistant bacteria.
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