A new iron oxidase from a moderately thermophilic iron oxidizing bacterium strain TI-1

Abstract

Iron oxidase was purified from plasma membranes of a moderately thermophilic iron oxidizing bacterium strain TI-1 in an electrophoretically homogeneous state. Spectrum analyses of purified enzyme showed the existence of cytochrome a, but not cytochrome b and c types. Iron oxidase was composed of five subunits with apparent molecular masses of 46 kDa (alpha), 28 kDa (beta), 24 kDa (gamma), 20 kDa (delta), and 17 kDa (epsilon). As the molecular mass of a native enzyme was estimated to be 263 kDa in the presence of 0.1% n-dodecyl-beta-D-maltopyranoside (DM), a native iron oxidase purified from strain TI-1 seems to be a homodimeric enzyme (alpha beta gamma delta epsilon)(2). Optimum pH and temperature for iron oxidation were pH 3.0 and 45 degrees C, respectively. The K(m) of iron oxidase for Fe(2+) was 1.06 mM and V(max) for O(2) uptake was 13.8 micromol x mg(-1) x min(-1). The activity was strongly inhibited by cyanide and azide. Purified enzyme from strain TI-1 is a new iron oxidase in which electrons of Fe(2+) were transferred to haem a and then to the molecular oxygen.

In situ spectroscopy on intact Leptospirillum ferrooxidans reveals that reduced cytochrome 579 is an obligatory intermediate in the aerobic iron respiratory chain

“…Classic reductionist studies that involve the structural and functional characterization of highly purified proteins in dilute solution have described a bewildering variety of different redox-active electron transport proteins in cell-free extracts derived from iron-grown Gram-negative (Cox and Boxer, 1978; Hart et al, 1991; Blake et al, 1992; Yarzábal et al, 2002, 2004), Gram-positive (Blake et al, 1993; Takai et al, 2001; Dinarieva et al, 2010), and Archaea (Hettmann et al, 1998; Dopson et al, 2005; Auernik and Kelly, 2008) bacteria. The most promising efforts to date have focused on the iron respiratory chain of Acidithiobacillus ferrooxidans , where an iron “respirasome” super complex has been defined that is comprised of 2 c -type cytochromes, a blue copper protein called rusticyanin, and an aa 3 -type terminal oxidase (Castelle et al, 2008).…”

Microbial Diversity and Abundance in a Representative Small-Production Coal Mine of Central China

“…Thiobacillus was found in coal beds in western Canada . It could oxidize iron and inorganic sulfur compounds and produce sulfuric acid in acid mine drainage. , Aquabacterium was the universal bacteria observed in water habitats, , including coal-produced water in Ordos Basin in China . The Alphaproteobacteria detected in mine water were affiliated with the genera of Rhodobacter and Novosphingobium.…”

Altererythrobacter muriae sp. nov., isolated from hypersaline Añana Salt Valley spring water, a continental thalassohaline-type solar saltern

“…This iron oxidase was first described in the moderately thermophilic iron-oxidizing bacterium strain TI-1. Purified enzyme from this strain had the ability to transfer electrons from Fe 2+ to heme a and then to molecular oxygen, but in a simpler way compared to Acidithiobacillus ferrooxidans indicating a diversity of iron oxidation enzyme systems in ironoxidizing bacteria [36]. In the same way, multidrug efflux pump component MtrF is present in strain SALINAS58 T and absent in the four closest relatives.…”