Fig. 8: Calculations of conditional Co^II availabilities in B₁₂-producing E. coli*.

a Calculated relationship between intracellular Co^II availability and normalised DNA occupancy (θ_D) by RcnR. θ_D of 0 and 1 are the maximum and minimum calculated DNA occupancies. The dynamic range (within which RcnR responds to changing intracellular Co^II availability) has been defined as θ_D of 0.01–0.99 (i.e. 1–99% of RcnR response). The calibrated maximum and minimum fold changes in rcnA transcript abundance (i.e. boundary conditions, see Supplementary Fig. 27) therefore correspond to θ_D of 0.01 and 0.99 in these calculations (red circles). θ_D for each growth condition (black circles) was calculated from the qPCR response in b, assuming a linear relationship between change in θ_D and change in transcript abundance (Eq. (10)). Corresponding Co^II availabilities are listed in Supplementary Table 8. b Transcript abundance (relative to untreated control) of the RcnR-regulated gene rcnA following 1 h exposure of E. coli* to increasing [Co^II], measured by qPCR. Data are the mean ± SD of n = 3 biologically independent replicates. Triangle shapes represent individual experiments (some data points overlap, experimental values are available in Source Data files).