title: Multi-haem cytochromes in Shewanella oneidensis MR-1: structures, functions and opportunities.
abstract: Multi-haem cytochromes are employed by a range of microorganisms to transport electrons over distances of up to tens of nanometres. Perhaps the most spectacular utilization of these proteins is in the reduction of extracellular solid substrates, including electrodes and insoluble mineral oxides of Fe(III) and Mn(III/IV), by species of Shewanella and Geobacter. However, multi-haem cytochromes are found in numerous and phylogenetically diverse prokaryotes where they participate in electron transfer and redox catalysis that contributes to biogeochemical cycling of N, S and Fe on the global scale. These properties of multi-haem cytochromes have attracted much interest and contributed to advances in bioenergy applications and bioremediation of contaminated soils. Looking forward, there are opportunities to engage multi-haem cytochromes for biological photovoltaic cells, microbial electrosynthesis and developing bespoke molecular devices. As a consequence, it is timely to review our present understanding of these proteins and we do this here with a focus on the multitude of functionally diverse multi-haem cytochromes in Shewanella oneidensis MR-1. We draw on findings from experimental and computational approaches which ideally complement each other in the study of these systems: computational methods can interpret experimentally determined properties in terms of molecular structure to cast light on the relation between structure and function. We show how this synergy has contributed to our understanding of multi-haem cytochromes and can be expected to continue to do so for greater insight into natural processes and their informed exploitation in biotechnologies.
authors.affiliation: Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
authors.forename: Marian
authors.initials: M
authors.lastname: Breuer
authors.affiliation: Pacific Northwest National Laboratory, Richland, WA, USA kevin.rosso@pnnl.gov.
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Rosso
authors.affiliation: Department of Physics and Astronomy, University College London, London WC1E 6BT, UK j.blumberger@ucl.ac.uk.
authors.forename: Jochen
authors.initials: J
authors.lastname: Blumberger
authors.affiliation: School of Biological Sciences and School of Chemistry, University of East Anglia, Norwich NR4 7TJ, UK j.butt@uea.ac.uk.
authors.forename: Julea N
authors.initials: JN
authors.lastname: Butt
mesh_terms: D020816:Amino Acid Motifs; D001709:Biotechnology; D003198:Computer Simulation; D003580:Cytochromes / Q000737:chemistry*; D003593:Cytoplasm / Q000378:metabolism; D004566:Electrodes; D004579:Electron Transport; D005290:Ferric Compounds / Q000737:chemistry; D006418:Heme / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D008024:Ligands; D008958:Models, Molecular; D010084:Oxidation-Reduction; D010455:Peptides / Q000737:chemistry; D025941:Protein Interaction Mapping; D020592:Shewanella / Q000378:metabolism*; D013053:Spectrophotometry; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D003580:Cytochromes; D005290:Ferric Compounds; D008024:Ligands; D010455:Peptides; D006418:Heme; D006639:Histidine
keywords: Marcus theory; cytochrome; electron transfer; haem; redox potential; respiration