Fig. 4

RcnA in cable bacteria. A Presence/absence table of nickel export genes in cable bacteria and related organisms of the Desulfobulbales order. Only HQ or closed (indicated with circle) genomes are shown. B Maximum‑likelihood phylogeny of putative cable bacteria RcnA and database (RefSeq) hits. Cable bacteria branches (green) and the closely related branches of the Geobacteraceae family are indicated. Black circles indicate ultrafast bootstrap values. The biochemically characterized RcnA of E. coli is indicated with a red arrow. The lowest common shared taxonomy is indicated per clade. C Alphafold2 structure predictions highlighting the expansion of the histidine‑rich loop in cable bacteria. Transmembrane helices are indicated in blue, the histidine‑rich loop is indicated in green