Using Transposon Mutagenesis to Systematically Uncover Novel Antibiotic Drug Targets in Burkholderia thailandensis

The rise of antibiotic resistance coupled with the decline in the development of new antimicrobials makes the task of finding novel antibiotic targets ever more important. The Seyedsayamdost Lab previously discovered that subinhibitory doses of trimethoprim (TMP), a known antibiotic, form a synthetic lethal combination with a deletion mutant of folE2, a folate biosynthetic gene in the β-proteobacterium Burkholderia thailandensis, which serves as a model for the human pathogen Burkholderia pseudomallei. Using systematic transposon mutagenesis screens, an additional 41 genes have been identified that show the synthetic lethal phenotype with low-dose TMP. Among these genes is the cobalamin dependent methionine synthase MetH and 4 genes involved in cobalamin biosynthesis. This process has not been exploited in bacteria as an antimicrobial target, and a known inhibitor of MetH does show slight dose dependent inhibition of WT B. thailandensis. Furthermore, supplementation of cobalamin to transposon mutants identified as part of cobalamin biosynthesis shows a mild rescue effect in the presence of TMP, suggesting cobalamin is important for survival in low-dose TMP. This study provides a new high throughput method to uncover novel antibacterial drug targets using transposon mutagenesis and low doses of clinically utilized antibiotics