C35: Molecular Discovery: Prediction of Tetracycline Destructase Oxi-Degradation Products

Presenter(s)

Benjamin Meron

Abstract or Description

Tetracycline antibiotics have been an important class of antibacterial agents since the 1940s. However, the inevitable emergence of bacterial resistance continuously threatens tetracyclines’ clinical application. Different generations of tetracycline antibiotics have been developed to overcome evolving resistance mechanisms, including efflux pumps and ribosomal protection proteins. Enzymatic inactivation is a newly emerging and largely unexplored resistance mechanism.

This study focuses on tetracycline destructases, Class A Flavin Monooxygenase (FMO) enzymes that inactivate tetracycline antibiotics through oxidation. We investigate the diverse oxidation mechanisms of tetracycline destructases, which can function through either Type 1 (Electrophilic C4a-Flavin-OOH as Flavin Monooxygenase) or Type 2 (Nucleophilic C4a-Flavin-OOH as Baeyer Viligerase) mechanisms.

Using HPLC assay and LCMS analysis, we have identified and predicted various tetracycline degradation products resulting from these oxidation mechanisms. The degradation pathways include tetracycline ABX ring modification, oxy-bridge formation, ring expansion, and A ring-opening. Our analysis covers multiple tetracycline variants including chlortetracycline, demeclocycline, doxycycline, and others, with molecular weights and structural changes documented for each degradation product.

This work expands our knowledge of tetracycline destructase oxidation mechanisms and provides insights into solving this newest resistance problem by identifying degradation products, which could potentially inform the development of new tetracycline antibiotics less susceptible to enzymatic inactivation. Understanding these mechanisms may also lead to novel inhibitors targeting tetracycline destructases, helping preserve the clinical efficacy of existing tetracyclines and combating the growing global antimicrobial resistance crisis in an era of diminishing antibiotic discovery.