Figure 4.

(A) F19 docked onto the cocrystal structure of the C-terminal domain of AgrA (AgrA_C) and a cognate oligonucleotide (PDB code 3BS1¹²). The docking was centered on the midpoint between V235 and I238 (shown in ball-and stick), two residues implicated in F19 binding by site-directed alanine mutagenesis. (B) Close up of the F19 binding site on the interface between AgrA_C and the DNA. (C) Electrophoretic mobility shift assay of AgrA_C from S. epidermidis as a function of F19 concentration. P3 DNA is an oligonucleotide corresponding to the P3 promoter sequence TAGAAACAATCTTATTTTTTTTGAATATAC. P3 DNA was radiolabeled with ³²P. The concentration of P3 DNA was 1 nM. 1 µM AgrA_C was added in lanes 2–5. F19 was titrated in at increasing concentrations while maintaining a constant concentration of 1% DMSO. The AgrA_C-DNA complex band is present at 0.1 µM F19, can barely be seen at 1 µM F19 and is absent at 10 and 100 µM F19. This gel is in compliance with the digital image and integrity policies.