Metal detoxification in <i>C. metallidurans</i> CH34 occurs via a variety of export systems encoded by 24 HMR gene clusters on 4 replicons.

achromosomal HMR resistance loci with genes that have a counterpart with a homologous function on a plasmid are called partially redundant, other loci are not-redundant. bUnderlined genes are regulators; bold genes are new in respect to an earlier report [8] (see also Table S2); geneparts created by a frameshift are indicated by ‘and“; IS- or Tn-insertions are indicated by a pipe symbol (|); truncated genes are indicated with a delta (Δ) symbol; (§), pbrR3 acts on zntA (Rmet_4594); (#),insertion of Tn6049 in pbrU; (†), czcB truncated by Tn6050-mediated rearrangement (inversion) and insertion of IS1088 between czcL and hns; (*), insertion of ISRme3 in nimA; (‡),insertion of IS1088 between hmyB and hmyA. cCMGI, Cupriavidus metallidurans CH34 Genomic Island; (P), PAGI-2 family. dMechanisms of HM detoxification: ExP, efflux (P1-ATPase); pCDF, putative CDF-like; seq, periplasmic sequestration; HgRed, reduction of Hg2+ into Hg0 which then volatilizes out of the cell; HgTra, tentative transport of Hg2+; ExChr, transport of chromate; FS, Fe-SOD (chrC); MFS, major facilitator superfamily permease (i.e., chrP); CDF, cation diffusion facilitator; ExHME, efflux by RND-HME type 1 to 4 (see text); ExHAE, efflux by HAE-RND (unknown substrate); ExCop, extrusion of Cu2+; AsRed (ExAs), reduction of HAsO42− into AsO2−and efflux of AsO2−. eFunctionality; +, active; (+), partly active; ?, unknown; -, inactive.