[S1-1] Effect of grafting the stem domain of staphylococcal pore forming toxin
Staphylococcus aureus express several kinds of pore forming toxins (PFTs) to lyse erythrocyte. PFTs are expressed as soluble monomer, and circularly assemble to form transmembrane β-barrel pore on the erythrocyte. PFTs are categorized into two groups according to the manner of assembly; one-component α-hemolysin (α-HL) and two-component γ-hemolysin (γ-HL). The α-hemolysin forms homo-heptamer, whereas γ-hemolysin is an octamer composed of four LukF and four Hlg2. Up to now, many engineered PFTs were analyzed for accumulating knowledge useful for development of PFTs, since it will be valuable for the development of nanopore sensors. In this presentation, we show the latest our knowledge of designing the β-barrel formed by six chimeric mutants composed of cap/rim domains of α-HL and stem of LukF or Hlg2 and the evaluation of their biochemical and structural characteristics. Biochemical analyses demonstrated that one of them act as one-component PFT although the stem is grafted from two-component PFT. Single particle analysis of negative staining microscopy revealed heptameric pore formed by the chimera. Based on these observations, the role of the stem domains of these PFTs and the importance of the sequence in the loop connecting between cap and stem domains are discussed.