Fig 8.
(A) Transcription of ilvE is regulated by CodY and CcpA. CAT activities are shown for a full-length ilvE promoter-cat fusion in the following background strains: UA159, ΔcodY strain, and ΔccpA strain. Cultures were grown in BHI medium as described in Materials and Methods. Statistical significance was determined by Student's t test. *, P ≤ 0.00001; **, P ≤ 0.0000001 (n = 3). Pairwise comparisons are represented by lowercase letters. (B) Genetic complementation of CodY restores transcriptional repression of ilvE. CAT activities are shown for a full-length ilvE promoter-cat fusion in the following background strains: UA159, ΔcodY strain, and complemented ΔcodY strain (ΔcodYc). Cultures were grown in BHI medium as described in Materials and Methods. Statistical significance was determined by Student's t test. *, P ≤ 0.00001 (n = 3). Pairwise comparisons are represented by lowercase letters. (C) Nutritional limitation and the absence of CodY enhance transcription of ilvE. CAT activities are shown for a full-length ilvE promoter-cat fusion in the following background strains: UA159, ΔcodY strain, and ΔccpA strain. Cultures were grown in FMC minimal medium as described in Materials and Methods. Statistical significance was determined by Student's t test. *, P ≤ 0.0000001 (n = 3). Pairwise comparisons are represented by lowercase letters.