MrkH and MrkI are required for repression of CRP in type 3 fimbriae.

(A) qRT-PCR analysis of mrkA expression was measured in WT, Δcrp, ΔcrpΔmrkH, ΔcrpΔmrkI, and ΔcrpΔmrkJ strains in LB medium. The results are representative of three independent experiments. Error bars indicate standard deviations. *P < 0.05 and ** P < 0.01 compared to the indicated group. The MrkA expression of WT, Δcrp, ΔcrpΔmrkH, ΔcrpΔmrkI, and ΔcrpΔmrkJ strains was determined in LB broth without (B) or with 0.5% glucose (C) by Western blot analysis against MrkA (the upper panel) and GAPDH antiserum (the lower panel, for internal control). The MrkA and GAPDH proteins are indicated by an arrow, respectively.