Fig. 3.

Characterization of periplasmic nitrate reductase (pNar) genes with possible perchlorate reductase activity. a Gene clusters containing both pnarGHJI and cld. b Alignment of selected Nar-type enzymes constructed using MUSCLE and edited using AliView. Perchlorate reductase residue positions α, β, and γ are structurally conserved and functionally significant [59]. Substrate utilization:+, reduced substrate in vivo or in vitro; −, did not reduce substrate; (+), predicted to reduce substrate. Tree: position in the phylogenetic tree at right. c Maximum-likelihood phylogeny of Nar-type molybdoenzymes constructed using MUSCLE and PhyML with 100 bootstraps. Four lineages are found in gene clusters with chlorite dismutase (blue background): group 1 PcrA, group 1 ClrA (SerA-like), group 2 ClrA (DdhA-like), and group 2 PcrA (pNarG-like). Genome bins encoding proteins from each group are indicated