FIG 4.

Robust statistical relation between discriminator A/T% and promoter’s response to DNA relaxation (act, activated; non, no significant variation; rep, repressed) is observed in phylogenetically distant bacterial species: (A) E. coli (P = 0.010, relaxation by norfloxacin in LZ54 versus LZ41 mutant strains) (17); (B) S. Typhimurium (P < 10⁻⁵); (C) D. dadantii (P < 10⁻³); (D) S. elongatus (P = 0.004); and (E) M. pneumoniae (P = 0.029). In enterobacteria, only σ⁷⁰ promoters were considered and were aligned at the −10 element. In the two other species, all promoters were aligned at their annotated TSS, resulting in a poorer definition of the signal and positional shifts. A/T% are computed in a 5-nt window centered around position −2 in the discriminator region, except for S. elongatus (position +4 after the TSS). Error bars represent 95% confidence intervals, and stars indicate the level of statistical significance (see Materials and Methods). A schematic phylogeny is depicted above.