Analysis of the domain structure of MarR and its binding with its upstream DNA sequence.

<p>(<b>A</b>) Analysis of the domain structure of MarR and its genomic location. The <i>Ms6508</i> gene encodes a typical MarR regulator containing an HTH-MARR domain. Ms6508 shares a 272-bp common upstream promoter region with the Ms6509–6510 gene cluster. (<b>B</b>) Bacterial one-hybrid assays for the interaction between MarR and the upstream sequence of the <i>marRAB</i> operon. A pair of pBXcmT/pTRG plasmids was co-transformed into the reporter strain and its growth was monitored together with that of self-activation controls on selective medium. Co-transformants containing the pBX-Rv2031/pTRG-Rv3133 plasmids (24) served as positive controls (CK⁺) and co-transformants containing the empty vectors pBX and pTRG served as negative controls (CK⁻). Only the MarR+Ms6508p co-transformant strains and a positive strain CK⁺ grew well on the screening medium, indicating that MarR specifically interacts with the upstream sequence of the <i>marRAB</i> operon, Ms6508p. (<b>C</b>) ChIP assays in wildtype and <i>marR</i> deletion mutant <i>M. smegmatis</i> strains. ChIP using preimmune (P) or immune sera (I) raised against MarR. The mycobacterial promoter Ms6141p was used as a negative control.