2.A.1.3.86
Antimony, SbIII and SbV, resistance MFS efflux protein of xxx aas and 14 TMSs in a 6 + 2 + 6 TMS arrangement with both 6 TMS domains having a 2 + 2 + 2 TMS arrangement (Yang et al. 2024). AntB is encoded on the chromosome of the arsenite-oxidizing bacterium Ensifer adhaerens E-60 that confers resistance to Sb(III) and Sb(V). The antB gene is adjacent to a gene encoding a LysR family transcriptional regulator termed LysR_ars, which is an As(III)/Sb(III)-responsive transcriptional repressor that is predicted to control expression of antB. Similar antB and lysR_ars genes are found in related arsenic-resistant bacteria, especially strains of Ensifer adhaerens, and the lysR_ars gene adjacent to antB encodes a member of a divergent subgroup of putative LysR-type regulators. Closely related AntB and LysR_ars orthologs contain three conserved cysteine residues, which are Cys17, Cys99, and Cys350 in AntB and Cys81, Cys289 and Cys294 in LysR_ars, respectively. Expression of antB is induced by As(III), Sb(III), Sb(V) and Rox(III) (4-hydroxy-3-nitrophenyl arsenite). Heterologous expression of antB in E. coli AW3110 (Δars) conferred resistance to Sb(III) and Sb(V) and reduced the intracellular concentration of Sb(III) (Yang et al. 2024).