Unexpected complexity of the Escherichia coli K-12 transcriptome architecture revealed by single nucleotide resolution RNA sequencing

To investigate the architecture of the E. coli K-12 transcriptome, we used two RNA-Seq technologies to analyze strand-specific transcription at single-nucleotide resolution. We analyzed the data by using an organizational schema to annotate the promoters and terminators that define transcription units across the genome. Our results showed that most (ca. two-thirds) operons have a single promoter and terminator, whereas one-third of operons contain multiple transcription units. We found substantial evidence for differential gene expression within complex operons, which we categorized based on operon architecture. E. coli K-12 strain MG1655 substrain BW38028 and isogenic rpoS mutant were cultured in minimal glucose media and the total transcriptome of log and stationary phase samples was sequenced.