Synthesis of a Phosphonate-Linked Aminoglycoside-Coenzyme A Bisubstrate and Use in Mechanistic Studies of an Enzyme Involved in Aminoglycoside Resistance

摘要

Aminoglycoside N-6'-acetyltransferases (AAC(6')s) are important determinants of antibiotic resistance. A good mechanistic understanding of these enzymes is essential to overcome aminoglycoside resistance. We have previously reported the synthesis of amide- and sulfonamide-linked aminoglycoside-coenzyme A conjugates, which were useful mechanistic and structural probes of AAC(6')s. We report here the synthesis of a phosphonate-linked aminoglycoside-coenzyme A variant, which is expected to be a superior mimic of the tetrahedral intermediate proposed for catalysis by AAC(6')s. This synthetic target is especially challenging for a number of reasons, including the presence of multiple functional groups, the water solubility of both starting materials, and incompatibility of P-III chemistry with water. We have overcome these challenges by adding the expensive coenzyme A in the last step by means of an elegant Michael-type addition onto a vinyl-phosphonate in water. Overall, a single protection step was needed. ne decreased inhibitory potency of this bisubstrate compared to that of the amide-linked analogue suggests that Enterococcus faecium AAC(6')-Ii may not stabilize the proposed tetrahedral intermediate, and may act mainly through proximity catalysis.