期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 110, 期 16, 页码 6346-6351出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1220074110
关键词
mineral respiration; multiheme cytochromes; proteoliposome
资金
- UK Biological and Biotechnological Sciences Research Council [BB/J013765, BB/H007288/1]
- US Department of Energy, Office of Biological and Environmental Research (BER) through the Subsurface Biogeochemical Research (SBR) Program [Pacific Northwest National Laboratory (PNNL) Scientific Focus Area (SFA)]
- Office of Basic Energy Sciences through the Geosciences Research Program
- BER
- BBSRC [BB/J013765/1, BB/H007288/1] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BB/J013765/1, BB/H007288/1] Funding Source: researchfish
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.
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