FIG. 2.

(A) Restriction map of the wild-type allele of agr in RN6390 (top) and the agr-null allele (Δagr) in PM466 (bottom). The agr P2 operon and P3 transcript are represented by the striped and shaded boxes, respectively. Chromosomal DNA on the 3′ end of the P2 operon and 3′ end of the P3 transcript are represented by black and gray lines, respectively. Abbreviations: C, ClaI; E, EcoRI; H, HincII; H/C, ligation of a HincII site with a T₄ polymerase blunt-ended ClaI site. (B) Chromosomal DNA from RN6390 (lane 1) and PM466 (lane 2) digested with EcoRI and analyzed by Southern hybridization using agr and flanking single-stranded DNA as the probe. DNA hybridizing to agr-flanking regions is marked with arrows.