Figure 2. The glycine‐rich motifs within the stem domain are required for the cytotoxic activity of other leukocidins.

• A, B
  Amino acid sequences of toxin S‐subunits depicting (A) Mut1 (∆112‐117) and (B) Mut2 (∆130‐134) domains, based on ClustalW alignment.
• C
  Viability of primary human PMNs following incubation with mutant toxin pairings measured using the viability dye CellTiter. Bars indicate mean ± SEM, with n = 3 donors.
• D–F
  Viability of primary human PMNs following incubation with WT or mutant toxin pairings. Insert: 2 μg per lane of purified recombinant toxins visualized by Coomassie Blue staining using a 12% SDS–PAGE gel. A^mut1 = HlgA^mut1, B^mut = HlgB^mut, C^mut1 = HlgC^mut1, S^mut1 = LukS‐PV^mut1, F^mut = LukF‐PV^mut. Bars indicate mean ± SEM, with n = 4 donors (D), n = 4 donors (E), and n = 5 donors (F).