Figure 2 .

Rationale for interpretation of panels A, B, and C of the bar graphs in Figures 3–6 and Figure S1, Figure S2, Figure S3, Figure S4, Figure S5, Figure S6, Figure S7, Figure S8, Figure S9, Figure S11, Figure S12, Figure S13, Figure S14, Figure S15, Figure S16. (A) The transcriptional hilA–lac fusion serves as a major readout for SPI1 expression. First, test the effects of a regulatory factor on hilA expression in both hilD⁺ and hilD⁻ backgrounds. (B) Second, test the effects of a regulatory factor on hilA expression in a background where the system can be induced via tetracycline control of rtsA with or without HilD. (C) Third, test the effects of a regulatory factor on hilD–lac transcriptional and hilD’-’lac translational locus fusions, which provide a readout of hilD transcription and translation, respectively, in the absence of HilD autoinduction. See detailed description of the experimental setup in Rationale and approach in Results.