Figure 4.
A, Relative expression of agr RNAIII, fnbA, and hla in MW2 and RN6390 parental Staphylococcus aureus strains and their respective mgrA mutant and mgrA-complemented strain sets. Expression levels are relative to that of the parental strain, which is arbitrarily set at 1. *P < .05, **P < .001, and ***P < .0001 vs their respective parental and mgrA-complemented strains. B, Binding of purified MgrA with the 287-bp fnbA promoter DNA (PfnbA), as determined by gel shift assay. The first lane represents the fnbA promoter DNA alone. Increasing amounts of purified MgrA (0.5, 1.0, 2.0, and 4.0 μg) were applied. The last lane represents purified MgrA alone (4.0 μg). In competition assays, MgrA was incubated with a presence of 5-fold excess of specific competitor (SC; 235-bp hla promoter DNA) or nonspecific competitor (non-SC; 162 bp from within the fnbA coding sequence).