Figure 4

Conservation and divergence in transcriptional regulation by σ-factors. (a) Clustering σ-factor binding patterns revealed conserved and divergent transcriptional regulation of 2,876 orthologous genes. (b) crp is regulated by σ⁷⁰ and σ³⁸ in both species, showing regulation conservation. (c) In Esherichia coli, cutA is a part of the dcuA-cutA-dipZ transcription unit (TU) and is regulated by σ⁷⁰ and σ³⁸, while cutA in Klebsiella pneumoniae is the first gene in its TU, and is directly bound by σ⁷⁰. (d) In K. pneumoniae, panD is a part of the panBCD TU, which is regulated by σ⁷⁰. However, in E. coli, panD is separated from panBC by yadD, making another distinct TU. These two TUs are both regulated by σ⁷⁰. (e) A genomic region containing ydeA and marC in both species was inverted, and this genomic inversion was accompanied by a transcription regulation switch between σ⁷⁰ and σ³⁸.