Figure 12.

Secretion of IglE mutants into J774 macrophages. Macrophages were infected with LVS expressing TEM fusions of wild-type IglE (WT), lipobox mutants, frameshift mutants FS1 to FS13 or substitution mutants within the FS4 region (for details of the mutants, see Fig. 6). After infection, cells were washed and loaded with CCF2/AM and analyzed using live cell microscopy. TEM β-lactamase activity is revealed by the blue fluorescence emitted by the cleaved CCF2 product, whereas uncleaved CCF2 emits a green fluorescence. The average secretion in % compared with the WT IglE protein, which was set as 100 %, and the SD from 2 samples (n = 2) from multiple experiments, in which 10,000 - 15,000 cells were counted in each experiment, are shown. The asterisks indicate that the secretion levels were significantly different than those of WT IglE-infected cells as determined by a 2-sided t-test with equal variance, including the Bonferroni correction for multiple pair-wise comparisons (***, P ≤ 0.001).