FIG 2.
The fasC mutation in serotype M3 GAS isolates is responsible for the low FasX sRNA levels, and subsequently the low level of SKA expression, that are characteristic of this serotype. Parental (MGAS2221) and fasC deletion mutant (2221ΔfasC) M1 isolates, parental (MGAS10870 and MGAS315) and fasC-complemented (10870fasCComp and 315fasCComp) M3 isolates, and a 315fasCComp derivative in which the fasC gene was remutated (315fasCMUT) were compared. (A) Northern blot analysis of FasX sRNA levels. RNA samples from exponential-phase cultures of the indicated strains were analyzed with FasX and 5S RNA-specific probes. The 5S RNA was used as a loading control. (B, C) Western blot analyses of SKA and SLO protein levels. Secreted proteins were isolated from exponential-phase cultures of the indicated strains and interrogated with antibodies against SKA and SLO. The SLO antibody was used as a loading control.