Fig 4. ArlRS is required for mgrA expression.

The mgrA gene has two promoters, depicted in (C). Lines labeled P2 and P1 show the fragments used to make transcriptional reporters. (A) Each mgrA promoter was independently cloned upstream of a promoterless copy of GFP in plasmid pCM11. Expression from the upstream promoter mgrA P2 (left) and downstream mgrA P1 (right) was assessed in the WT strain LAC (black) and the arlRS mutant (blue). (B) Western blot showing ArlR and MgrA protein levels at various time points (hours). (D) Quantification of MgrA protein levels in LAC (black, solid line) and the arlRS mutant (blue, solid line), and growth curves of the same strains (dotted lines). Quantification is representative of three separate experiments.