Figure 9.

Hypothetical Model for the Sensing of Mn²⁺ Ions, the Transduction of the Mn²⁺ Signal, and the Regulation of Expression of the mntCAB Operon That Encodes the Mn²⁺ Transporter.

The presence of two membrane-spanning domains in ManS (closed boxes) was predicted from a hydropathy plot (Kyte and Doolittle, 1982), and the presence of a DNA binding domain in ManR (hatched box) was predicted from the strong similarity of the deduced amino acid sequence to the DNA binding motif of OmpR in E. coli (Martínez-Hackert and Stock, 1997). His and Asp residues that might be involved in a phosphorelay are indicated by the encircled H and D, respectively.