A Novel marRAB Operon Contributes to the Rifampicin Resistance in Mycobacterium smegmatis
Figure 1
Analysis of the domain structure of MarR and its binding with its upstream DNA sequence.
(A) Analysis of the domain structure of MarR and its genomic location. The Ms6508 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) Bacterial one-hybrid assays for the interaction between MarR and the upstream sequence of the marRAB 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 marRAB operon, Ms6508p. (C) ChIP assays in wildtype and marR deletion mutant M. smegmatis strains. ChIP using preimmune (P) or immune sera (I) raised against MarR. The mycobacterial promoter Ms6141p was used as a negative control.
