Fig. 8.
Thermodynamic characterisation of a set of sensors.
A, The set of cytosolic protein-based metal sensors from Salmonella with cognate metal ion(s) and allosteric mechanism of regulation shown, as described in [93]. B, Thermodynamic cycle depicting the allosteric coupling of metal (M) binding and DNA (D) binding by metal sensor proteins (P) [211]. C, Fractional occupancy of target DNA binding site(s) with respective metal sensor protein as a function of buffered metal concentration, following determination of K1–4, and number of sensor molecules and target DNA-sites per cell (B), sensor protein abundance and number of target DNA binding sites as described in [93]. D, the ranges of total (triangles) and the available (buffered; circles) metal concentrations in Salmonella. Total metal was determined in cells grown in minimal media with (closed triangles) and without (open triangles) metal supplementation [93]. Open triangles obscured for Mn(II) and Zn(II). Available metal reflects the mid-point of each sensor's dynamic range in (c). The concentration equating to one hydrated atom per cell is shown by a dashed line.