FIG. 2.

Uptake of berberine (⧫), berberine in the presence of INF55 (⋄), hybrid SS14 (▴), hybrid SS14-M (▪), and hybrid SS14-P (•) into S. aureus cells: (a) wild-type 8325-4 S. aureus cells; (b) NorA-knockout (K1758 ΔnorA) S. aureus cells; (c) NorA-overexpressing (K2378 NorA++) S. aureus cells. Uptake was measured by monitoring the increases in fluorescence at 517 nm (excitation at 355 nm) and is expressed as arbitrary units (A.U.). All compounds were present at a concentration of 3 μM. The curves are representative of at least three independent experiments.