In vivo probing of the DNA-binding Architecture by bacterial arginine repressor. Escherichia coli str. K-12 substr. MG1655

Although DNA motifs recognized by the transcription factors (TFs) have been determined, challenges remain in probing in vivo architecture of TF-DNA complexes on a genome-wide scale. Here, we show in vivo architecture of Escherichia coli arginine repressor (ArgR)-DNA complexes using chromatin immunoprecipitation coupled with sequencing (ChIP-exo). The identified 62 ArgR-binding loci were classified into three groups, comprised of single, double, and triple peak-pairs, respectively. Each peak-pair has unique 93 bp-long (±2 bp) ArgR-binding sequence containing two ARG boxes (39 bp) and residual sequence. Moreover, the peak-pairs provided the three ArgR-binding modes defined by the position of the two ARG boxes, indicating that the formation of DNA bending apparently centered between the pair of ARG boxes facilitates the non-specific contacts between ArgR subunits and the residual sequences. Thus, our data postulate the in vivo architecture of ArgR-DNA complexes to understand its transcription regulatory mechanism. Overall design: ChIP-exo profiles of ArgR (+Arginine) and ArgR (-Arginine) were generated by deep sequencing in duplicates using Illumina MiSeq.