FIG 7.

Model of transposon-mediated response to copper. Copper enters the cell nonspecifically or via transporters. The proposed high-affinity association of copper at the N terminus of DA-LP is shown. Elevated copper levels induce transcription through an undetermined copper-dependent regulator. Expression of genes downstream of lit2 contributes to copper resistance by various mechanisms, including copper efflux, copper oxidation, and regulation of additional genes. Coinduction of Lit2 simultaneously converts lipoproteins from the DA-LP form to the lyso-LP, which is proposed to reduce copper coordination at the lipoprotein N terminus. While both DA-LP and lyso-LP are sensed by the TLR2/TLR6 heterodimer, the lyso form is overall a less potent ligand at TLR2/TLR6 than DA-LP and a poor TLR2/TLR1 ligand.