Wai Kwan Tang | PubMed Health

PubMed2026

Evolution, Mechanisms, and Therapeutic Implications of Mobile Tetracycline Destructases.

Tetracycline destructases (TDases) pose an emerging global threat by enzymatically inactivating all generations of tetracycline (Tet) antibiotics, including last-resort agents such as tigecycline. Despite their recent identification, TDases have rapidly disseminated worldwide, largely driven by mobile genetic elements and environmental reservoirs. This review synthesizes current knowledge on TDase genomics, structural and catalytic mechanisms, ecological niches, and clinical impacts. We detail the mechanistic distinctions between type 1 and type 2 TDases, emphasizing their divergent structural configurations and substrate specificity profiles. Additionally, we examine strategies for therapeutic intervention, highlighting progress in structure-guided inhibitor development. Key gaps remain in understanding ancestral reservoirs, evolutionary trajectories, and effective surveillance strategies. Addressing these areas through integrative evolutionary, biochemical, and ecological studies is critical for mitigating the clinical spread and therapeutic impact of TDases globally.

Humans↗

PubMed2025

C10-Benzoate Esters of Anhydrotetracycline Inhibit Tetracycline Destructases and Recover Tetracycline Antibacterial Activity.

Tetracyclines (TCs) are an important class of antibiotics threatened by enzymatic inactivation. These tetracycline-inactivating enzymes, also known as tetracycline destructases (TDases), are a subfamily of class A flavin monooxygenases (FMOs) that catalyze hydroxyl group transfer and oxygen insertion (Baeyer-Villiger type) reactions on TC substrate scaffolds. Semisynthetic modification of TCs (e.g., tigecycline, omadacycline, eravacycline, and sarecycline) has proven effective in evading certain resistance mechanisms, such as ribosomal protection and efflux, but does not protect against TDase-mediated resistance. Here, we report the design, synthesis, and evaluation of a new series of 22 semisynthetic TDase inhibitors that explore D-ring substitution of anhydrotetracycline (aTC) including 14 C10-benzoate ester and eight C9-benzamides. Overall, the C10-benzoate esters displayed enhanced bioactivity and water solubility compared to the corresponding C9-benzamides featuring the same heterocyclic aryl side chains. The C10-benzoate ester derivatives of aTC were prepared in a high-yield one-step synthesis without the need for protecting groups. The C10-esters are water-soluble, stable toward hydrolysis, and display dose-dependent rescue of tetracycline antibiotic activity in E. coli expressing two types of tetracycline destructases, represented by TetX7 (Type 1) and Tet50 (Type 2). The best inhibitors recovered tetracycline antibiotic activity at concentrations as low as 2 μM, producing synergistic scores <0.5 in the fractional inhibitory concentration index (FICI) against TDase-expressing strains of E. coli and clinical P. aeruginosa. The C10-benzoate ester derivatives of aTC reported here are promising new leads for the development of tetracycline drug combination therapies to overcome TDase-mediated antibiotic resistance.

Anti-Bacterial Agents↗