ArlRS is required for <i>mgrA</i> expression.

<p>The <i>mgrA</i> gene has two promoters, depicted in (C). Lines labeled P2 and P1 show the fragments used to make transcriptional reporters. (A) Each <i>mgrA</i> promoter was independently cloned upstream of a promoterless copy of GFP in plasmid pCM11. Expression from the upstream promoter <i>mgrA</i> P2 (left) and downstream <i>mgrA</i> P1 (right) was assessed in the WT strain LAC (black) and the <i>arlRS</i> 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 <i>arlRS</i> mutant (blue, solid line), and growth curves of the same strains (dotted lines). Quantification is representative of three separate experiments.