FIG. 1.

(A) Sequence of the ace promoter region. Potential −35 and −10 region and ribosome binding site (RBS) sequences are underlined. The transcriptional start site (+1) is in boldface, and the Ers box is boxed. (B) EMSA with the promoter region of the ace gene and different concentrations (2 to 0.2 μg) of His₆-ErsHTH protein. (C) EMSA of His₆-ErsHTH binding to the D4-labeled DNA fragment containing the ace regulatory region. Amplifications were performed with D4-Pu and D4-Pr (Table 2). Crude cell extracts prepared from an E. faecalis Δers mutant strain (0.1 μg protein) were added to all of the reaction mixtures. Shown are the labeled ace promoter without protein (lane 1), with His₆-ErsHTH (1 μg protein) (lane 2), with His₆-ErsHTH and an unlabeled competitor (lane 3), and with His₆-ErsHTH and a nonspecific DNA fragment (internal fragment of the ef1843 gene) (lane 4).