FIG 1.
Screening workflow. A diverse collection of 26,000 synthetic compounds was screened using the PywaC reporter system, which generated 54 active compounds. Activity was confirmed for 46 compounds upon retesting. Confirmed active compounds were subjected to growth inhibition studies using B. subtilis, which revealed 35 potent active compounds. Subsequently, a membrane-permeabilization counterscreen was used to exclude membrane-active compounds, which yielded 25 priority active compounds. For 9 of these compounds, the activity phenocopied known cell wall-active antibiotics, as PywaC activity could be suppressed with the inclusion of osmoprotectants (MSM) in growth medium, and produced morphological defects in B. subtilis; these constituted novel cell wall-active compounds.