FIGURE 4.

The large conformational change of CagL is not responsible for integrin binding. A, top, sedimentation velocity experiment of CagL^L156/F204C (10 μm) at 50,000 rpm in 50 mm sodium acetate, 150 mm sodium chloride, pH 4.5 (blue crosses), or 50 mm Tris, 150 mm sodium chloride, pH 7.5 (green crosses). Fitted data are shown as solid lines and the residuals (bottom) are plotted. CagL^L156/F204C sediments with an s_20,w^* of 2.1 and 2.0 for pH 4.5 and 7.5, respectively. B, relative adhesion of AGS cells to CagL^L156/F204C were measured using the same assay. Data were normalized to 500 nm CagL^WT, pH 7.5, with standard deviations displayed. C, translocation of CagA monitored by its phosphorylation at various pH values by CagL^L156/F204C. D, relative induction of IL-8 secretion as measured by ELISA at various pH values by CagL^L156/F204C. Data were normalized to a positive control.