S164: Structure and Chemistry of Nonribosomal Peptide Natural Product Biosynthesis

Nonribosomal peptide biosynthetic pathways contain complex enzyme machinery responsible for preparation of nonproteinogenic amino acids, templated synthesis of peptides and functionalization of the products. A significant number of the chemical steps utilize coenzyme A or phosphopantetheinyl thioesters as integral components. Presented is the design and chemical synthesis of non-hydrolyzable thioester analogs for use as probes into the structure and chemistry of nonribosomal peptide biosynthetic enzymes.  A general strategy was developed to prepare amide-based analogs for use in a wide range of applications. For example, the structure of an unusual dioxygenase involved in the biosynthetic pathway to vancomycin/teicoplanin antibiotics was elucidated using this strategy.  The enzyme DpgC catalyzes a key step in the production of 3,5-dihydroxyphenylglycine,  a nonproteinogenic building block in this class of natural products.  In addition, the preparation of tethered multidomain synthetase enzymes allowed detailed insights into protein structure and substrate trafficking.  The synthetic small molecule probes both assist in the formation of diffraction quality crystals and yield valuable details into the chemistry.