Characterization of OmcA Mutants from Shewanella oneidensis MR‐1 to Investigate the Molecular Mechanisms Underpinning Electron Transfer Across the Microbe‐Electrode Interface

Electricity production in microbial fuel cells (MFCs) is an emerging green alternative to the use of fossil fuels. Shewanella oneidensis MR‐1 (SOMR‐1) is a Gram‐negative bacterium, adapted to MFCs due to its ability to link its bioenergetic metabolism through the periplasm to reduce extracellular electron acceptors. OmcA is a highly abundant outer‐membrane cytochrome of SOMR‐1 cells and is involved in the extracellular electron transfer to solid acceptors and electron shuttles. To investigate electron transfer performed by OmcA towards final acceptors, site directed mutagenesis was used to disturb the axial coordination of hemes. Interactions between OmcA and redox partners such as iron and graphene oxides, and electron shuttles were characterized using nuclear magnetic resonance and stopped‐flow experiments. Results showed that solid electron acceptors do not come into close proximity to the hemes, in agreement with experimentally observed slow electron transfer. In contrast, mutation of the distal axial ligand of heme VII changes the driving force of OmcA towards electron shuttles and reduces the affinity of the FMN:OmcA complex. Overall, these results reveal a functional specificity of particular hemes of OmcA and provide guidance for the rational design of mutated SOMR‐1 strains optimized for operating in different microbial electrochemical devices.

[1]  K. Rosso,et al.  Flavin Binding to the Deca-heme Cytochrome MtrC: Insights from Computational Molecular Simulation , 2015, Biophysical journal.

[2]  D. Richardson,et al.  Redox Linked Flavin Sites in Extracellular Decaheme Proteins Involved in Microbe-Mineral Electron Transfer. , 2015, Scientific Reports.

[3]  M. Yun,et al.  Changes in carbon electrode morphology affect microbial fuel cell performance with Shewanella oneidensis MR-1 , 2015 .

[4]  Hye Suk Byun,et al.  Shewanella oneidensis MR-1 nanowires are outer membrane and periplasmic extensions of the extracellular electron transport components , 2014, Proceedings of the National Academy of Sciences.

[5]  Bruno M. Fonseca,et al.  Exploring the molecular mechanisms of electron shuttling across the microbe/metal space , 2014, Front. Microbiol..

[6]  R. Louro,et al.  Redox tuning of the catalytic activity of soluble fumarate reductases from Shewanella. , 2014, Biochimica et biophysica acta.

[7]  D. Richardson,et al.  The X‐ray crystal structure of Shewanella oneidensis OmcA reveals new insight at the microbe–mineral interface , 2014, FEBS letters.

[8]  G. Bazan,et al.  Modification of Abiotic–Biotic Interfaces with Small Molecules and Nanomaterials for Improved Bioelectronics , 2014 .

[9]  Heming Wang,et al.  A comprehensive review of microbial electrochemical systems as a platform technology. , 2013, Biotechnology advances.

[10]  Jeffrey A. Gralnick,et al.  Flavin Electron Shuttles Dominate Extracellular Electron Transfer by Shewanella oneidensis , 2013, mBio.

[11]  J. Fredrickson,et al.  Redox reactions of reduced flavin mononucleotide (FMN), riboflavin (RBF), and anthraquinone-2,6-disulfonate (AQDS) with ferrihydrite and lepidocrocite. , 2012, Environmental science & technology.

[12]  D. Richardson,et al.  The crystal structure of the extracellular 11-heme cytochrome UndA reveals a conserved 10-heme motif and defined binding site for soluble iron chelates. , 2012, Structure.

[13]  C. Chia,et al.  University of Malaya from the Selectedworks of Huang Nay Ming Simple Room-temperature Preparation of High- Yield Large-area Graphene Oxide Simple Room-temperature Preparation of High-yield Large-area Graphene Oxide , 2022 .

[14]  John M. Zachara,et al.  Structure of a bacterial cell surface decaheme electron conduit , 2011, Proceedings of the National Academy of Sciences.

[15]  Q. Bashir,et al.  Dynamics in electron transfer protein complexes , 2011, The FEBS journal.

[16]  Hua Zhang,et al.  A BRIEF REVIEW ON GRAPHENE-NANOPARTICLE COMPOSITES , 2010 .

[17]  Jonathan G. Lees,et al.  Transient protein-protein interactions: structural, functional, and network properties. , 2010, Structure.

[18]  A. Pacheco,et al.  The effect of detergents and lipids on the properties of the outer-membrane protein OmcA from Shewanella oneidensis , 2010, JBIC Journal of Biological Inorganic Chemistry.

[19]  Paul C Mills,et al.  Characterization of an electron conduit between bacteria and the extracellular environment , 2009, Proceedings of the National Academy of Sciences.

[20]  M. Tien,et al.  Kinetic Characterization of OmcA and MtrC, Terminal Reductases Involved in Respiratory Electron Transfer for Dissimilatory Iron Reduction in Shewanella oneidensis MR-1 , 2009, Applied and Environmental Microbiology.

[21]  S. Elliott,et al.  Electrochemical interrogations of the Mtr cytochromes from Shewanella: opening a potential window , 2008, JBIC Journal of Biological Inorganic Chemistry.

[22]  T. Straatsma,et al.  In vitro evolution of a peptide with a hematite binding motif that may constitute a natural metal-oxide binding archetype. , 2008, Environmental science & technology.

[23]  D. R. Bond,et al.  Shewanella secretes flavins that mediate extracellular electron transfer , 2008, Proceedings of the National Academy of Sciences.

[24]  J. Lloyd,et al.  Secretion of Flavins by Shewanella Species and Their Role in Extracellular Electron Transfer , 2007, Applied and Environmental Microbiology.

[25]  S. Lower,et al.  Specific Bonds between an Iron Oxide Surface and Outer Membrane Cytochromes MtrC and OmcA from Shewanella oneidensis MR-1 , 2007, Journal of bacteriology.

[26]  Liang Shi,et al.  High-affinity binding and direct electron transfer to solid metals by the Shewanella oneidensis MR-1 outer membrane c-type cytochrome OmcA. , 2006, Journal of the American Chemical Society.

[27]  M. Ubbink,et al.  An NMR‐based docking model for the physiological transient complex between cytochrome f and cytochrome c 6 , 2005, FEBS letters.

[28]  Andreas Kappler,et al.  Phenazines and Other Redox-Active Antibiotics Promote Microbial Mineral Reduction , 2004, Applied and Environmental Microbiology.

[29]  Harry B Gray,et al.  Electron tunneling through proteins , 2003, Quarterly Reviews of Biophysics.

[30]  J. Worrall,et al.  Transient protein interactions studied by NMR spectroscopy: the case of cytochrome C and adrenodoxin. , 2003, Biochemistry.

[31]  Byung Hong Kim,et al.  A mediator-less microbial fuel cell using a metal reducing bacterium, Shewanella putrefaciens , 2002 .

[32]  Byung Hong Kim,et al.  Electrochemical activity of an Fe(III)-reducing bacterium, Shewanella putrefaciens IR-1, in the presence of alternative electron acceptors , 1999 .

[33]  C. Myers,et al.  Replication of plasmids with the p15A origin in Shewanella putrefaciens MR‐1 , 1997, Letters in applied microbiology.

[34]  D. Lovley,et al.  Humic substances as electron acceptors for microbial respiration , 1996, Nature.

[35]  M Czjzek,et al.  Site-directed mutagenesis of tetraheme cytochrome c3. Modification of oxidoreduction potentials after heme axial ligand replacement. , 1992, The Journal of biological chemistry.

[36]  P. Dutton,et al.  The thermodynamic properties of some commonly used oxidation-reduction mediators, inhibitors and dyes, as determined by polarography. , 1981, Biochimica et biophysica acta.

[37]  M. Dixon.  The acceptor specificity of flavins and flavoproteins. 3. Flavoproteins. , 1971, Biochimica et biophysica acta.

[38]  J. Davis,et al.  Preliminary Experiments on a Microbial Fuel Cell , 1962, Science.

[39]  L G WHITBY,et al.  A new method for preparing flavin-adenine dinucleotide. , 1953, The Biochemical journal.

[40]  M. C. Potter.  Electrical Effects Accompanying the Decomposition of Organic Compounds. II. Ionisation of the Gases Produced during Fermentation , 1911 .

[41]  C. Salgueiro,et al.  Unraveling the electron transfer processes of a nanowire protein from Geobacter sulfurreducens. , 2016, Biochimica et biophysica acta.

[42]  R. Louro.  Introduction to Biomolecular NMR and Metals , 2013 .

[43]  M. Vanoni,et al.  Identifying and quantitating FAD and FMN in simple and in iron-sulfur-containing flavoproteins. , 1999, Methods in molecular biology.

[44]  V. Massey.  The microestimation of succinate and the extinction coefficient of cytochrome c. , 1959, Biochimica et biophysica acta.