The periplasmic 9.6-kilodalton c-type cytochrome of Geobacter sulfurreducens is not an electron shuttle to Fe(III).
Geobacter sulfurreducens contains a 9.6-kDa c-type cytochrome that was previously proposed to serve as an extracellular electron shuttle to insoluble Fe(III) oxides. However, when the cytochrome was added to washed-cell suspensions of G. sulfurreducens it did not enhance Fe(III) oxide reduction, whereas similar concentrations of the known electron shuttle, anthraquinone-2,6-disulfonate, greatly stimulated Fe(III) oxide reduction. Furthermore, analysis of the extracellular c-type cytochromes in cultures of G. sulfurreducens demonstrated that the dominant c-type cytochrome was not the 9.6-kDa cytochrome, but rather a 41-kDa cytochrome. These results and other considerations suggest that the 9.6-kDa cytochrome is not an important extracellular electron shuttle to Fe(III) oxides.
Lloyd
J R
JR
Department of Microbiology, University of Massachusetts, Amherst, Massachusetts 01003, USA.
Blunt-Harris
E L
EL
Lovley
D R
DR
D003574:Cytochrome c Group / Q000378:metabolism*; D004579:Electron Transport; D004591:Electrophoresis, Polyacrylamide Gel; D005290:Ferric Compounds / Q000378:metabolism*; D006089:Gram-Negative Anaerobic Bacteria / Q000201:enzymology* / Q000378:metabolism; D008970:Molecular Weight; D019897:Periplasm / Q000378:metabolism
D003574:Cytochrome c Group; D005290:Ferric Compounds