Fig. 1: Conserved domain organisation of HRZ/BTS proteins and predicted protein fold.

a Phylogeny of HRZ, BTS and BTS-Like (BTSL) proteins from selected organisms across the green lineage (left) and their domain organisation (right). The hemerythrin (Hr)-like sequences are marked H1, H2 and H3. Dark grey indicates the presence, and light grey the absence, of iron-binding ligands. The question mark indicates that one of the six ligands is absent or not aligned. For full species names and sequence IDs, see Supplementary Table 1. Phylogenetic analysis was performed using www.phylogeny.fr54. The scale bar indicates the number of amino acid substitutions per site. b AlphaFold2 model of BTSL2. The Hr-like folds are predicted to be ordered H2–H1–H3 in a tightly packed configuration.