Proteomic Analysis of Differential Protein Expression in Acidithiobacillus ferrooxidans Grown on Ferrous Iron or Elemental Sulfur

In this study, a proteomic analysis of Acidithiobacillus ferrooxidans by two-dimensional electrophoresis identified 24 proteins that were differentially expressed when the cells were grown on ferrous iron (Fe2+) or elemental sulfur (S°). Sixteen of these proteins were upregulated by growth on S° or downregulated by growth on Fe2+, including four proteins involved in disulfide bond reduction such as pyridine nucleotide-disulfide oxidoreductase, heterodisulfide reductase subunit B, thioredoxin-disulfide reductase, and cysteine desulfurase IscS, and three proteins involved in saccharide metabolism. A total of eight proteins were upregulated by growth on Fe2+ or downregulated by S°. Northern blots further confirmed the differences in transcription for these differentially expressed proteins. We functionally characterized cysteine desulfurase IscS, and found that its overexpression in E. coli promoted the growth of the cells in LB containing 2.5 % sodium thiosulfate. Our results provide new insights into the molecular basis for S° and Fe2+ oxidation by this extreme acidophile.