Figure 3.

Competition between σ⁷⁰ and σ³⁸ in overlapping promoter regions. (a) Recruitment of RNA polymerase (RNAP) core enzyme to promoters upstream of 1,139 σ³⁸-specific genes was recovered when rpoS was knocked out. RNAP binding intensity on the y-axis was the chromatin immunoprecipitation and microarray (ChIP-chip), intensity; the three red lines represent the first, second, and third quantiles. (b) Comparison of transcriptional expression of genes in wild type (WT) and ΔrpoS strains. Of 1,139 genes with σ³⁸-specific promoters,178 had up-regulated transcription (red background) and 291 had down-regulated transcription (blue background). (c) Expression level of σ⁷⁰ and σ³⁸ was measured at both th transcriptional and translational levels. The amount of σ⁷⁰ was abundant in exponential and stationary phase, and so it was absent in rpoS. (d) After rpoS knock-out, up-regulated genes were more strongly bound by σ⁷⁰ than down-regulated genes.