Rapid electron exchange between surface-exposed bacterial cytochromes and Fe(III) minerals.
Proc Natl Acad Sci U S A
; 110(16): 6346-51, 2013 Apr 16.
Article
de En
| MEDLINE
| ID: mdl-23538304
ABSTRACT
The mineral-respiring bacterium Shewanella oneidensis uses a protein complex, MtrCAB, composed of two decaheme cytochromes, MtrC and MtrA, brought together inside a transmembrane porin, MtrB, to transport electrons across the outer membrane to a variety of mineral-based electron acceptors. A proteoliposome system containing a pool of internalized electron carriers was used to investigate how the topology of the MtrCAB complex relates to its ability to transport electrons across a lipid bilayer to externally located Fe(III) oxides. With MtrA facing the interior and MtrC exposed on the outer surface of the phospholipid bilayer, the established in vivo orientation, electron transfer from the interior electron carrier pool through MtrCAB to solid-phase Fe(III) oxides was demonstrated. The rates were 10(3) times higher than those reported for reduction of goethite, hematite, and lepidocrocite by S. oneidensis, and the order of the reaction rates was consistent with those observed in S. oneidensis cultures. In contrast, established rates for single turnover reactions between purified MtrC and Fe(III) oxides were 10(3) times lower. By providing a continuous flow of electrons, the proteoliposome experiments demonstrate that conduction through MtrCAB directly to Fe(III) oxides is sufficient to support in vivo, anaerobic, solid-phase iron respiration.
Texte intégral:
1
Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Composés du fer III
/
Modèles moléculaires
/
Shewanella
/
Cytochromes
/
Complexes multiprotéiques
/
Transport d'électrons
Langue:
En
Journal:
Proc Natl Acad Sci U S A
Année:
2013
Type de document:
Article
Pays d'affiliation:
Royaume-Uni