Figure 4

rCST9 directly affected protein changes in S4 and MDM. (A) S4 (1 × 10⁴ CFU/sample) was incubated with various dilutions rCST9 for 4 h, then plated to determine bacteria viability via replication. 50 pg of rCST9 significantly decreased S4 viability compared with all other tested dilutions (P< 0.05). (B) A portion of the S4 incubated with 50 pg of rCST9 was given to MDM (MOI 40:1) where it was killed significantly better (P< 0.05) than infected MDM alone but not as effectively as rCST9 and S4 given concurrently to MDM. (C) The schematic showing that MS analysis identified numerous proteins involved in bacterial metabolic pathway that were either downregulated or eliminated by CST9. (D) TEM analysis of untreated S4 revealed an intact, uninterrupted cell wall. However, the membranes of S4 incubated with 50 pg of rCST9 for 4 h had the periplasmic space disrupted, and in some areas, the bacterial membrane was discontinuous. Where applicable data are presented as mean ± SEM and asterisk signifies significant differences of *P < 0.05 or **P < 0.01 as indicated. Scale bar, 0.5 µm.