Figure 1.
Blue light-activated cytolysis in E. coli BL21 and Nissle 1917 using pDawn. (A) Synthesized and purified ClyA lyses SKBR3 cancer cells in vitro. Purified ClyA (0.3 nM) resulted in a 6-fold increase in cytotoxicity, significant (p < 0.001) over both the negative control vehicle (water) and the positive control (digitonin, 12 μM) (n = 6 samples per group). (B) BL21(pDawn-ClyA) shows specific, blue light-dependent expression of the ~34 kDa ClyA protein. (C) In contrast to BL21(pDawn-mCherry), BL21(pDawn-ClyA) exhibits blue light-dependent cytolysis on blood agar. (D) Blue light-dependent cytolysis on blood agar is seen from Nissle 1917(pDawn-ClyA) but not from Nissle 1917(pDawn-mCherry). (E) Time course for mCherry protein expression from BL21(pDawn-mCherry) using 480 nm light. Light-dependent mCherry expression in BL21 cultures (n = 3 per time point) is significantly higher (p < 0.001) at all illumination times beyond 3 h (asterisks omitted at 4, 5, 6, and 8 hour time points for clarity). All data are presented as mean ± SD.