FIG. 2.

MtsR controls the expression of the sia operon. GAS cells were used to inoculate complete (ZTH; black symbols) or iron-limiting (NTA; empty symbols) medium and incubated at 37°C, and cell growth was monitored over time. Culture samples were taken in the exponential-growth phase, and total proteins and RNA were prepared. (A) Growth curves. Cell growth is expressed as Klett units. Squares indicate the wild-type NZ131, and circles represent the mtsR mutant (ZE491). (B) Western blot analysis of Shr and SiaA proteins. Proteins, standardized based on cell number, were separated by SDS-PAGE and were reacted with rabbit antibody to Shr (top panel) or SiaA (bottom panel). (C) RT-PCR analysis of sia genes. cDNA synthesized from 1 μg of total RNA by use of gene-specific primers was amplified by PCR and separated on an agarose gel. PCRs are shown for the housekeeping gene recA (top panel) and the shr gene (bottom panel).