ADDRESSING THE CHALLENGES OF ANTIBIOTIC RESISTANCE, DEREPLICATION, AND BIOSYNTHESIS

Abstract

Antibiotics form the cornerstone of modern medicine, facilitating advancements in numerous healthcare fields and contributing to unprecedented increases in human life expectancy. However, the efficacy of these life-saving drugs is now jeopardized by the rise of antimicrobial resistance. This growing threat is exacerbated by the slow pace of new antibiotic discoveries. The drug discovery process is both time-consuming and costly, and efforts to identify novel antibiotics often result in the rediscovery of known antibiotics, further hindering progress. To combat antibiotic resistance and facilitate the discovery of novel drugs, several approaches can be employed. First, understanding the mechanisms of resistance found in environmental bacteria is crucial for preparing against the potential mobilization of these resistance mechanisms into pathogenic bacteria. Second, developing tools that make the drug discovery process less costly and time-consuming can accelerate the discovery rate and broaden participation in drug discovery efforts. Finally, understanding how bacteria synthesize natural product antibiotics provides invaluable information that can be leveraged in drug discovery efforts, including synthetic biology approaches. This thesis addresses efforts and challenges in the various aspects of drug discovery. To enhance our understanding of environmental resistance mechanisms, I conducted a screen for ciprofloxacin-inactivating enzymes and characterized the activity of a previously reported ciprofloxacin-inactivating enzyme, CrpP. These findings highlight the difficulties associated with discovering synthetic antibiotic-inactivating enzymes. To contribute to drug discovery, I expanded the Antibiotic Resistance Platform and developed a streamlined version to improve antibiotic dereplication efforts, thereby accelerating the natural product discovery process. Additionally, I investigated the mechanism of β-serine biosynthesis, a nonproteinogenic amino acid found in the antibiotic edeine. By elucidating how β-serine is synthesized, this information can be applied to synthetic biology approaches for drug discovery.