FIG 1 .

Domain structure and inner membrane localization of ImcH. (A) The monocistronic imcH gene was interrupted 18 times using transposon mutagenesis (black triangles). All transposon mutants in this gene failed to reduce soluble Fe(III) citrate. (B) ImcH has three putative transmembrane helices (gray bars), seven putative c-type heme motifs (black bars), and a region of homology to NapC/NirT-like quinone oxidoreductases (gray box). The first putative c-type heme motif is CXXXCH. (C) Sucrose-gradient separated ImcH-His×6 membrane fractions, tested for succinate dehydrogenase (SDH) activity as a marker of inner membranes, and probed using an anti-6×His antibody. ImcH was detected only in fractions with SDH activity.