Fig. 5.

Z nucleotides activate nonrelated RRs under nonstimulatory conditions and in an HK-independent manner. (A) Strains IFC6016 (WT), IFC6017 (purA⁻), IFC6018 (arcB⁻ purA⁻), and IFC6019 (arcB⁻ arcA⁻ purA⁻), all of which carry the ArcA-P−activatable cydA-lacZ reporter, were grown aerobically (nonstimulatory conditions) in LB medium containing 0.1 M Mops (pH 7.4), to an OD₆₀₀ of 0.3 (white bars) or 0.6 (gray bars). As a control, strain IFC6016 (WT) was grown anaerobically (stimulatory conditions) in the same medium. (B) Strains IFC6020 (WT), IFC6021 (purA⁻), and IFC6022 (cpxA⁻ purA⁻), all of which carry the CpxR-P−activatable cpxP-lacZ reporter, were grown in LB medium at pH 5.8 (nonstimulatory conditions) to an OD₆₀₀ of 0.3 (white bars) or 0.6 (gray bars). To obtain reference values, strain IFC6020 (WT) was grown in LB medium at pH 8.8 (stimulatory conditions). (C) Strains IFC6026 (WT), IFC6027 (purA⁻), and IFC6028 (phoQ⁻ purA⁻), all of which carry the PhoP-P−activatable iraM-lacZ reporter, were grown in LB medium (nonstimulatory conditions) to an OD₆₀₀ of 0.3 (white bars) or 0.6 (gray bars). As a control, strain IFC6026 (WT) was grown in M9 defined minimal medium supplemented with 0.2% (wt/vol) glucose, and, at an OD₆₀₀ of 0.3, cells were harvested and resuspended in a magnesium-free M9 medium, and incubation continued during 30 min (stimulatory conditions). (D) Cultures of strains IFC6023 (WT), IFC6024 (purA⁻), and IFC6025 (rcsC⁻ purA⁻), all of which carry the RcsB-P−activatable bdm-lacZ reporter, were grown in LB medium (nonstimulatory conditions) to an OD₆₀₀ of 0.3 (white bars) or 0.6 (gray bars). As a control, strain IFC6023 (WT) was grown in M9 defined minimal medium supplemented with 0.2% (wt/vol) glucose, and, at an OD₆₀₀ of 0.3, 500 mM NaCl were added, and incubation continued for 30 min (stimulatory conditions). For A−D, β-galactosidase activity is measured and expressed in Miller units. Data represent the averages from three independent experiments, and SDs are indicated.