E. coli MqsR and MqsA whole DNA microarray and nickel DNA enrichment microarray

Here evidence is presented that MqsR and B3021 are a novel toxin-antitoxin (TA) system related to biofilm development and quorum sensing. Using whole-transcriptome studies and nickel enrichment DNA binding microarrays coupled with cell survival studies in which MqsR was overexpressed in isogenic mutants, we identified seven genes involved in MqsR toxicity (clpX, clpP, yfjZ, cspD, relB, relE, and hokA). Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed consistent induction of the seven genes by the overexpression of MqsR as well as induction of nutrient starvation related genes (cstA, rpoS, and dps). Taken together, our results indicate that MqsR toxicity is caused via CspD (a DNA replication inhibitor), other TA systems (RelE/RelB and YfjZ), HokA (a small membrane toxin peptide), and nutrient-starvation conditions induced via CstA, RpoS, and Dps. Additionally, in vivo binding results show antitoxin B3021 binds to the promoter regions of genes encoding essential proteins for stress, growth and normal physiology. Strain: E. coli K-12 BW25113 wt and mqsR deleted mutant Medium: LB medium Temperature: 37 oC Time: 24 h Cell type: Biofilm grown on glass wool and planktonic culture