The bc(1) complex of the iron-grown acidophilic chemolithotrophic bacterium Acidithiobacillus ferrooxidans functions in the reverse but not in the forward direction. Is there a second bc(1) complex?
Acidithiobacillus ferrooxidans is an acidophilic chemolithotrophic bacterium that can grow in the presence of either a weak reductant, Fe(2+), or reducing sulfur compounds that provide more energy for growth than Fe(2+). Here we first review the latest findings about the uphill electron transfer pathway established in iron-grown A. ferrooxidans, which has been found to involve a bc(1) complex. We then provide evidence that this bc(1) complex cannot function in the forward direction (exergonic reaction), even with an appropriate substrate. A search for the sequence of the three redox subunits of the A. ferrooxidans bc(1) complex (strain ATCC 19859) in the complete genome sequence of the A. ferrooxidans ATCC 23270 strain showed the existence of two different bc(1) complexes in A. ferrooxidans. Cytochrome b and Rieske protein sequence comparisons allowed us to point out some sequence particularities of these proteins in A. ferrooxidans. Lastly, we discuss the possible reasons for the existence of two different "classical" bc(1) complexes and put forward some suggestions as to what role these putative complexes may play in this acidophilic chemolithotrophic bacterium.
Brasseur
Gaël
G
Laboratoire de Bioénergétique et Ingénierie des Protéines, Institut de Biologie Structurale et Microbiologie, CNRS, Marseille, France. brasseur@ibsm.cnrs-mrs.fr
Bruscella
Patrice
P
Bonnefoy
Violaine
V
Lemesle-Meunier
Danielle
D
D016947:Acetobacteraceae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D000595:Amino Acid Sequence; D003573:Cytochrome b Group / Q000737:chemistry / Q000235:genetics; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007501:Iron; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000235:genetics; D007527:Isoenzymes / Q000737:chemistry / Q000378:metabolism; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D013455:Sulfur
D003573:Cytochrome b Group; D007506:Iron-Sulfur Proteins; D007527:Isoenzymes; C037989:Rieske iron-sulfur protein; D013455:Sulfur; D007501:Iron; D014450:Electron Transport Complex III