cbb3-type cytochrome oxidase in the obligately chemolithoautotrophic Thiobacillus sp. W5

Abstract

A highly active cytochrome c oxidase has been purified 75-fold from the neutrophilic obligately autotrophic Thiobacillus sp. W5. UV/visible and electron paramagnetic resonance spectroscopy revealed that the cytochrome c oxidase contains low-spin hemes c and low- and high-spin hemes b. HPLC analysis confirmed the presence of heme b as the sole type of non-covalently bound heme. The combined data from atomic absorption spectroscopy and electron paramagnetic resonance indicate the absence of CuA and suggest the presence of a bimetallic heme-copper redox center. These results show that Thiobacillus sp. W5 contains a cbb3-type oxidase, which is a member of the heme–copper oxidase family. The cbb3-type oxidase was the only cytochrome oxidase expressed in aerobically and micro-aerobically grown Thiobacillus sp. W5 cultures.