pyogenes to human epithelial cells, wild-type and scl1-mutated S. pyogenes ST2, in the exponential phase, were examined for adhesion to human HEp-2 epithelial cells. Adhesion of

ST2, was decreased about 70% compared with that of the wild-type (P < 0.01, Figure 2B), suggesting that Erastin Scl1 is critical in the adherence of S. pyogenes to human epithelial cells. Ectopic expression of Scl1 on E. coli To exclude the interference of other streptococcal surface factors during the adhesion, and to test whether Scl1 is sufficient to mediate the adherence to human epithelium cells, we expressed Scl1 on the heterologous bacteria E. coli. Signal sequence (SS), WM region, and part of the L region of Scl1 were not constructed into OmpA-containing vector. E. coli DH5α with OmpA-containing vector was represented as

ET2, whereas E. coli DH5α with truncated Scl1-OmpA construct was represented as ET3. To confirm the expression of Scl1 protein on the surface of E. coli, we performed FACS analysis on whole bacteria. A right-shift of peak fluorescence recognized by anti-Scl1 antibodies was observed in ET3, but not in either E. coli DH5α or ET2. (Figure 3A). Consistent with this observation, the negative staining of electron microscopy revealed hairy structures in ET3, but these structures were not identified in either E. coli DH5α or ET2 (Figure 3B). To further demonstrate that Scl1 was ectopically expressed selleck on E. coli, outer membrane fraction of proteins was https://www.selleckchem.com/products/Methazolastone.html isolated from ET2 and ET3. Western blot analysis with anti-Scl1 antibodies identified Scl1 in the outer membrane fraction of ET3 but not in that of ET2 (Left panel, Figure 3C). Consistently, a molecular weight shift was revealed by anti-OmpA antibodies

in the outer membrane fraction of ET3 (Right panel, Figure 3C). Thus, our data confirmed that Scl1 protein was ectopically expressed on E. coli and can be detected by anti-Scl1 antibodies. Figure 3 Ectopic expression of Scl1 on E. coli. (A) FACS analysis on whole bacteria pre-incubated with (white profile) or without (gray profile) anti-Scl1 antibodies, followed by FITC-conjugated secondary antibodies. (B) Electron microscope view of whole bacteria after negative staining with Tau-protein kinase sodium phosphotungstate. Asterisks indicate ectopic expressed Scl1 on the E. coli surface. Bars represent 100 nm. ET2, E. coli expressing vector only. ET3, E. coli expressing Scl1. (C) Western blot analysis with anti-Scl1 (left panel) and anti-OmpA (right panel) antibodies in the outer membrane fraction of ET2 and ET3. Adherence of Scl1-expressed E. coli to human epithelial cells Adhesion analysis demonstrated that Scl1-expressed E. coli ET3 dramatically increased its adherence to HEp-2, compared with that of vector-expressed E. coli ET2 and E. coli DH5α (Figure 4A). Pre-incubation of E. coli ET3 with proteinase K significantly attenuated the Scl1-mediated increase in adhesion, suggesting that Scl1 proteins on E. coli are critical for this binding.