Regulation of the expression of the Acidithiobacillus ferrooxidans rus operon encoding two cytochromes c, a cytochrome oxidase and rusticyanin

Abstract

The regulation of the expression of the rus operon, proposed to encode an electron transfer chain from the outer to the inner membrane in the obligate acidophilic chemolithoautroph Acidithiobacillus ferrooxidans, has been studied at the RNA and protein levels. As observed by Northern hybridization, real-time PCR and reverse transcription analyses, this operon was more highly expressed in ferrous iron- than in sulfur-grown cells. Furthermore, it was shown by immunodetection that components of this respiratory chain are synthesized in ferrous iron- rather than in sulfur-growth conditions. Nonetheless, weak transcription and translation products of the rus operon were detected in sulfur-grown cells at the early exponential phase. The results strongly support the notion that rus-operon expression is induced by ferrous iron, in agreement with the involvement of the rus-operon-encoded products in the oxidation of ferrous iron, and that ferrous iron is used in preference to sulfur.

Purification and Characterization of Sulfide:Quinone Oxidoreductase from an Acidophilic Iron-Oxidizing Bacterium,Acidithiobacillus ferrooxidans

“…Although the transfer of electrons from ferrous iron to oxygen has not been conclusively established, the electron transfer pathway is thought to involve two cytochromes c (Cyc2 and Cyc1), a rusticyanin, and an aa 3 -type cytochrome c oxidase. [4][5][6] On the other hand, although some enzyme activities thought to be involved in the aerobic oxidation of elemental sulfur by A. ferrooxidans were detected, [7][8][9][10][11][12][13][14][15][16] the oxidation pathway of elemental sulfur has not yet been clearly elucidated.…”

Reduction of Hg2+with Reduced Mammalian Cytochromecby CytochromecOxidase Purified from a Mercury-ResistantAcidithiobacillus ferrooxidansStrain, MON-1

“…Although the same amounts of ferrous iron were oxidized when strains MON-1 and ATCC 23270 gave maximum cell yields, the growth yield of strain MON-1 was It is well known that aa 3 type cytochrome c oxidase is one of the most important components of the iron oxidation enzyme system in A. ferrooxidans. 32,[35][36][37][38][39][40][41][42][43][44] We have found that mercury resistant-A. ferrooxidans strains SUG 2-2 and MON-1 have high Fe 2þ -dependent mercury volatilization activity in the cells, 30,31) and that cytochrome c oxidase purified from strain SUG 2-2 reduces Hg 2þ with Fe 2þ as electron donor volatilizing metalic mercury (Hg 0 ) outside of the cells.…”

Differential gene expression in response to copper in Acidithiobacillus ferrooxidans strains possessing dissimilar copper resistance

“…Bacteria cells were grown in fresh 9K medium with different concentrations of copper ions. Growth was followed by direct cell counting in a Neubauer chamber (Yarzabal et al, 2004), the oxidation capacities of ferrous ions were determined using the potassium dichromate (K 2 Cr 2 O 7 ) titration method, and growth curves were generated. Cells were harvested at an early logarithmic phase of cell growth by centrifugation at 4 C for 10 min at 12,000 rpm using a 5804R centrifuge (Eppendorf, Wesbury, NY, USA).…”