FIGURE 1.
IsdX1SS-GST is anchored to the cell wall by sortase A. A, IsdX1SS-GST is a translational hybrid between IsdX1 (colored green), the cell-wall sorting signal of BcpA (colored red), and glutathione S-transferase. The diagram displays the precursor (P1) of IsdX1SS-GST, and the signal peptidase (P2) and sortase-cleaved products (M). B, sortase cleavage products were detected in urea -SDS-release cytoplasmic fractions by immunoblot with α-GST antisera. Antisera raised against B. cereus sortase D and B. anthracis sortase A allowed for their detection by immunoblot. Labels indicate the sortase (srtA, srtD, srtDC207A, or none) and substrate (bcpA-gst or isdX1SS-gst) expressed in each strain. C, bacilli cell wall extracts were digested with mutanolysin. IsdX1 anchoring was analyzed by immunoblot with α-IsdX1 antibodies.