Benzothiazinones mediate killing of Corynebacterianeae by blocking decaprenyl phosphate recycling involved in cell wall biosynthesis

Benzothiazinones (BTZs) are a new class of sulphur containing heterocyclic compounds which target DprE1, an oxidoreductase involved in the epimerisation of decaprenyl-phosphoribose (DPR) to decaprenyl-phosphoarabinose (DPA) in the Corynebacterineae, such as Corynebacterium glutamicum and Mycobacterium tuberculosis. As a result, BTZ inhibition leads to inhibition of cell wall arabinan biosynthesis. Previous studies have demonstrated the essentiality of dprE1. In contrast, Cg-UbiA a ribosyltransferase, that catalyzes the first step of DPR biosynthesis prior to DprE1, when genetically-disrupted, produced a viable mutant, suggesting that while BTZ biochemically targets DprE1, killing also occurs through chemical synthetic lethality, presumably through the lack of decaprenyl phosphate recycling. To test this hypothesis, a derivative of BTZ, BTZ043 was examined in detail against C. glutamicum and C. glutamicum::ubiA. The wild type strain was sensitive to BTZ043; however C. glutamicum::ubiA was found to be resistant, despite possessing a functional DprE1. When the gene encoding C. glutamicum Z-decaprenyl diphosphate synthase (NCgl2203) was over-expressed in wild type C. glutamicum, resistance to BTZ043 was further increased. This data demonstrates that in presence of BTZ, the bacilli accumulate DPR and fail to recycle decaprenyl phosphate, which results in the depletion of decaprenyl phosphate and ultimately leads to cell death.