Fig 5.

Flow-cytometry analysis of the interaction between recombinant rAP1_M6 and GAS or Lactococcus bacteria. A. FACS analysis of GAS WT_M6, its deletion mutant Δap1_M6 and the complemented strain Δap1_M6(pAM ap1_M6). B. FACS analysis of L. lactis carrying either an empty vector (pAM), or a plasmid containing the FCT-1 M6 pilus operon (pAM-pilus M6) or the same operon except for a deletion in the ap1_M6 gene. In all cases bacteria were incubated with 5 µg of biotinylated rAP1_M6 and binding of the protein to the cells was revealed by R-Phycoerythrin-conjugated Streptavidin. Black histograms indicate staining of bacteria with streptavidin alone, while red histograms correspond to bacteria incubated with rAP1_M6 protein and then streptavidin. Binding was calculated by subtracting the mean fluorescence of bacteria stained with biotinylated rAP1_M6 protein from that of the unstained bacteria (ΔMFI). The average ΔMFI value from three independent experiments is shown.