Kinetics and Mechanism of Mineral Respiration: How Iron Hemes Synchronize Electron Transfer Rates

Valentin Chabert, Lucille Babel, Michael P. Füeg, Maksym Karamash, Edwin S. Madivoli, Nelly Herault, Joana M. Dantas, Carlos A. Salgueiro, Bernd Giese, Katharina M. Fromm

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)

Abstract

Anaerobic microorganisms of the Geobacter genus are effective electron sources for the synthesis of nanoparticles, for bioremediation of polluted water, and for the production of electricity in fuel cells. In multistep reactions, electrons are transferred via iron/heme cofactors of c-type cytochromes from the inner cell membrane to extracellular metal ions, which are bound to outer membrane cytochromes. We measured electron production and electron flux rates to 5×105 e s−1 per G. sulfurreducens. Remarkably, these rates are independent of the oxidants, and follow zero order kinetics. It turned out that the microorganisms regulate electron flux rates by increasing their Fe2+/Fe3+ ratios in the multiheme cytochromes whenever the activity of the extracellular metal oxidants is diminished. By this mechanism the respiration remains constant even when oxidizing conditions are changing. This homeostasis is a vital condition for living systems, and makes G. sulfurreducens a versatile electron source.

Original languageEnglish
JournalAngewandte Chemie - International Edition
Early online date28 Jan 2020
DOIs
Publication statusE-pub ahead of print - 28 Jan 2020

Keywords

  • electron transfer
  • Geobacter sulfurreducens
  • iron heme
  • silver nanoparticles
  • silver proteins

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