KSEF RDE: Novel, Improved Aminoglycoside Antibiotics through Enzymatic Total Synthesis/Combinatorial Biosynthesis

Aminoglycosides are first line antimicrobial drugs used to combat Gram-negative bacteria, but side effects have diminished their applications in favor of other antibiotics (â-lactams, macrolides, fluoroquinolones). However, renewed interest in novel, improved aminoglycosides has emerged, mainly due to the fact that multi-resistant bacteria rendered most of the above-mentioned, more fashionable broad spectrum antibiotics useless, particularly â-lactams of the penicillin and cephalosporin series. Gram-negative bacteria of the genera Klebsiella, Acinetobacter, Pseudomonas, and Enterobacter are particularly problematic, encompassing a majority of the deadliest groups of bacteria that are multi-resistant to virtually all of the currently used antibiotics. We hypothesize that aminoglycosides can be rationally re-designed to generate more potent, novel antibiotics while simultaneously eliminating unwanted side effects and preventing the development of drug resistance strains. To test this hypothesis, we will achieve the following two specific aims: (i) develop enzyme cassettes suitable for the synthesis of deoxysugar, deoxyaminosugar, and aminocyclitol building blocks of aminoglycosides and (ii) identify and generate glycosyltransferases capable of assembling aminocyclitol and deoxyaminosugar building blocks to di-, tri-, and tetra-saccharidal aminoglicyoside scaffolds. It is our expectation that the methodology of combinatorial enzymatic synthesis will offer a strong science-based approach to develop aminoglycoside antimicrobials that takes advantage of the inherent flexibility of biosynthetic enzymes involved in natural product assembly, and this method will undoubtedly complement efforts using traditional, and often cumbersome, total synthetic and semisynthetic strategies. The results will ultimately pave the way for the development of therapeutically-useful next generation aminoglycosides, effective drugs to fight life-threatening diseases caused by multi-resistant Gram-negative bacteria