Fig. 1
From: Fine control of metal concentrations is necessary for cells to discern zinc from cobalt
Zn(II), Co(II) and related formaldehyde sensors of Salmonella. Allosteric mechanisms of Salmonella sensors and structural models based on Protein Data Bank files 4MTD for Zur (a), 4WLW for ZntR (b), 5LCY for both RcnR (c) and FrmRE64H (d) with identified DNA-binding sites (bold), upstream of target genes. The DNA sequences shown were used for fluorescence anisotropy and orange bars indicate the region amplified by end point PCR and quantitative PCR. Known or inferred ligands for effector binding are enlarged: Zur contains a Cys4-structural site and at least one sensory site. The dinuclear Zn(II) site of E. coli ZntR (PDB: 1Q08) is shown, noting that solution studies of Salmonella ZntR indicate a mononuclear site5, 29. An RcnR Co(II) site has been proposed, which may also include Glu32 70. FrmRE64H and FrmR have overlapping sites for formaldehyde (Cys35, Pro2) and metal binding (Cys35, His60 and either His64 for FrmRE64H or Glu64 for FrmR)40. Cognate effectors are depicted
