TABLE 3.

Structures of flavonoids, their inhibitory effects on LmrA and YxaF binding to the LmrA/YxaF boxes, and derepression of the lmrAB and yxaGH promoters repressed by them

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  • a The structure of flavone is presented at the top of the column.

  • b Data are presented as an evaluation of the in vitro results compared to that of the in vivo results. The in vitro results were obtained through experiments involving gel retardation, which were performed as described in the legend of Fig. 5B, where those with the addition of quercetin are shown. According to the Ki values for the eight flavonoids regarding the binding of LmrA and YxaF to the lmrAB and yxaGH probes, the inhibitory effects are classified as follows: ++++, <1.0 mM; +++, 1.0 to 2.5 mM; ++, 2.5 to 10 mM; +, >10 mM; −, no inhibition. The actual Ki values are given for the combinations of LmrA/YxaF repressors and boxes belonging to the categories ++++, +++, and ++. The parenthetical Ki values are given in mM. The in vivo results were obtained through experiments involving lacZ fusions, which were performed as described in the legend of Fig. 6, where those with the addition of quercetin are shown. According to the peak β-Gal activity after the addition of each flavonoid, the derepression degrees of the lmrAB and yxaGH promoters repressed by LmrA and YxaF are graded as follows: +++, >20 nmol/min per OD; ++, 10 to 20 nmol/min per OD; +, <10 nmol/min per OD; −, no derepression.

  • c The data for the quercetin effect are those shown in Fig. 5B and 6.