Exploring structural motifs necessary for substrate binding in the active site of Escherichia coli pantothenate kinase.

The coenzyme A (CoA) biosynthetic enzymes have been used to produce various CoA analogues, including mechanistic probes of CoA-dependent enzymes such as those involved in fatty acid biosynthesis. These enzymes are also important for the activation of the pantothenamide class of antibacterial agents, and of a recently reported family of antibiotic resistance inhibitors. Herein we report a study on the selectivity of pantothenate kinase, the first and rate limiting step of CoA biosynthesis. A robust synthetic route was developed to allow rapid access to a small library of pantothenate analogs diversified at the β-alanine moiety, the carboxylate or the geminal dimethyl group. All derivatives were tested as substrates of Escherichia coli pantothenate kinase (EcPanK). Four derivatives, all N-aromatic pantothenamides, proved to be equivalent to the benchmark N-pentylpantothenamide (N5-pan) as substrates of EcPanK, while two others, also with N-aromatic groups, were some of the best substrates reported for this enzyme. This collection of data provides insight for the future design of PanK substrates in the production of useful CoA analogues.