Figure 13.

Model of heavy metal resistance in the Sulfolobales. (1) CopA and CopB export Cu outside the cell with ATP consumption. CopM is a metal chaperone that forms part of the Cop system that also includes a transcriptional factor called CopT (not shown). (2)PolyP can sequester cations via its negatively charged surface. (3) PolyP can also be degraded by PPX into inorganic phosphate to be exported outside the cell along with cations via PitA or Pho84 transporters. (4) Some proteins also act by sequestering metal ions, for example Dps. The mechanism for which metals enter the cell is still unknown.