Bacillus subtilis tagD mutant

The bacterial cell wall has been a celebrated target for antibiotics and holds real promise as a target for the discovery of new chemical matter to surmount pervasive multi-drug resistance among pathogenic bacteria. While the walls of Gram-negative bacteria are composed primarily of peptidoglycan, those of Gram-positives are more substantial and contain, in addition, large amounts of the polymer teichoic acid, covalently attached to peptidoglycan. Wall teichoic acids are a diverse group of phosphate-rich, extracellular polysaccharides that have been largely regarded as ancillary cell surface components. Recently, wall teichoic acid was shown to be essential to the proper rod-shaped cell morphology of the prototype Gram-positive bacterium Bacillus subtilis and an important virulence factor for the human pathogen Staphylococcus aureus. Thus wall teichoic acid synthesis is an intriguing target for the development of new cell wall-active antibiotics. Nevertheless, recent studies have shown that the dispensability of genes encoding teichoic acid biosynthetic enzymes in both B. subtilis and S. aureus is paradoxical and complex. Here, we report here on the discovery of a promoter (PywaC), which is sensitive to lesions in teichoic acid synthesis. Using this promoter we developed a luminescent, cell-based, reporter system to take a chemical-genetic approach to understanding the complexity of wall teichoic acid biogenesis using a large collection of antibiotics of well characterized biological activity. Our results reveal surprising interactions among undecaprenol, peptidoglycan and teichoic acid biosynthesis that help explain the complexity of teichoic acid gene dispensability. Furthermore, the new reporter assay represents an exciting avenue for the discovery of novel antibacterial molecules that impinge broadly on Gram-positive bacterial cell wall biogenesis. Keywords: comparison between depleted and repleted tagD mutant A conditional xylose-inducible tagD mutant of B. subtilis was generated. Cells were grown in the presence and absence of xylose. Cells grown in the absence of xylose stopped growing after tagD depletion. Two time points were analysed. Time point 1: early depletion. Time point 2: late depletion, i.e. close to death.