FIGURE 7.

Contacts of the HbpW1015A. A, silver-stained polyacrylamide gel of samples of cross-linked cells obtained by immunopurification using anti-Hbp antibody. Cells expressing the indicated Hbp derivatives were incubated with DSP. Crude membrane fractions were isolated, solubilized, and immunopurified with anti-Hbp. Eluates were treated with DTT to cleave DSP prior to SDS-PAGE and silver staining. The asterisks indicate from top to bottom the specific cross-linked products BamA, SurA, and BamB pulled down with Hbp-L110C/G348C. p, pro-Hbp; m, mature Hbp. B, immunoblot analysis of samples obtained as described under A using antibodies against the Hbp passenger, BamA, BamB, and SurA. The antibodies against Hbp recognize both pro-Hbp and mature Hbp, which are indicated on the left side of the panels as p and m, respectively.