Date of Award
Doctor of Philosophy (PhD)
Antibiotic resistance is an increasing concern for global health care, with some estimates suggesting that 10 million people will die from antibiotic resistant infections in the year 2050. Fueling this prospect, few antimicrobials are being actively developed and recently commercial entities have fled from the development of new anti-infectives. New antimicrobials and drug development strategies are urgently needed to revitalize this critical pipeline. While many putative antibiotics demonstrate promising in vitro potency, they routinely fail in vivo due to poor drug-like properties (e.g. oral bioavailability, serum-half life, toxicity) resulting in overly expensive drug development pipelines. Fortunately, drug-like properties can be modified through the addition of chemical protecting groups to create “prodrugs”. Lipophilic prodrugging strategies have been primarily deployed to remedy poor oral absorption but have also been utilized as a means of specifically delivering active drug to specific cells and tissue types. Here we demonstrate that lipophilic prodrugging of phosphonate antibiotics through a carboxy ester modification increases membrane permeability and enhances antimicrobial potency. Unfortunately, many lipophilic prodrugging strategies are rapidly cleaved in vivo by serum esterases rendering these potency and transport gains useless during clinical settings. Using three species of staphylococci, we identify and biochemically characterize two esterases, GloB and FrmB responsible for the activation of carboxy ester prodrugs. Additionally, we solve the three-dimensional structures of both GloB and FrmB, facilitating additional structure-guided design of promoieties. Finally, we characterize the substrate specificity of human and mouse sera, enabling the development of promoieties which are selectively activated by microbial species. These findings not only allow the development of novel anti-staphylococcals but lay the framework for identification of microbial-specific prodrug design and design of long-lasting serum prodrugs. As lipophilic prodrugging expands the number of compounds that are membrane permeable, we expect that this approach will facilitate an expansion of the number of potential drugs.
Chair and Committee
Audrey R. Odom John Joseph Jez
Daniel E. Goldberg, Jeffrey P. Henderson, Juliane Bubeck-Wardenburg, Timothy A. Wencewicz,
Miller, Justin J., "Prodrug Activation in Staphylococci and the Implications for Antimicrobial Development" (2021). Arts & Sciences Electronic Theses and Dissertations. 2374.