FIGURE 1.

Fpn cleaves BFT on the cell surface. An fpn− ETBF strain (a) and an isogenic wild-type strain (b) were grown to mid-log phase. Intact cells were then treated with proteinase K (PK) for the indicated time, and Western blots were performed using antisera against SurA and either BFT (a) or Fpn (b). (c) Cells were grown to mid-log phase and separated from the culture medium by centrifugation. The intact fpn− cells were mock treated or treated with purified Fpn or the Fpn (C180A) mutant for 30 min at 37°C. Whole-cell (WC) and culture medium (sup) fractions were then analyzed by Western blot using antisera against BFT and SurA