Figure 9.

The K. pneumoniae O7 ABC transporter is unable to export the E. coli O9a O-PS. Overnight cultures of E. coli manA (CWG634; O9a O-PS control) and E. coli manA Δwzm-wzt::aph3-A (CWG638) transformed with plasmids encoding either the O9a (pWQ332) or O7 (pWQ1014) transporter (Wzm-Wzt-His₆) were subcultured for 3 h in medium supplemented with 0.1% d-mannose and 0.1% l-arabinose to induce O-PS biosynthesis and transporter expression, respectively. LPS profiles were examined in proteinase K–treated whole-cell lysates using silver-stained SDS-polyacrylamide gels (top). α-His₅ Western blots of whole cell lysates were used to confirm transporter expression (bottom). O-PS present in lanes 2 and 4 of the Western blot is a result of nonexported O-PS, evident from its lack of silver staining.