title: New Insight into Microbial Iron Oxidation as Revealed by the Proteomic Profile of an Obligate Iron-Oxidizing Chemolithoautotroph.
abstract: Microaerophilic, neutrophilic, iron-oxidizing bacteria (FeOB) grow via the oxidation of reduced Fe(II) at or near neutral pH, in the presence of oxygen, making them relevant in numerous environments with elevated Fe(II) concentrations. However, the biochemical mechanisms for Fe(II) oxidation by these neutrophilic FeOB are unknown, and genetic markers for this process are unavailable. In the ocean, microaerophilic microorganisms in the genus Mariprofundus of the class Zetaproteobacteria are the only organisms known to chemolithoautotrophically oxidize Fe and concurrently biomineralize it in the form of twisted stalks of iron oxyhydroxides. The aim of this study was to identify highly expressed proteins associated with the electron transport chain of microaerophilic, neutrophilic FeOB. To this end, Mariprofundus ferrooxydans PV-1 was cultivated, and its proteins were extracted, assayed for redox activity, and analyzed via liquid chromatography-tandem mass spectrometry for identification of peptides. The results indicate that a cytochrome c4, cbb3-type cytochrome oxidase subunits, and an outer membrane cytochrome c were among the most highly expressed proteins and suggest an involvement in the process of aerobic, neutrophilic bacterial Fe oxidation. Proteins associated with alternative complex III, phosphate transport, carbon fixation, and biofilm formation were abundant, consistent with the lifestyle of Mariprofundus.
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California, USA barco@usc.edu.
authors.forename: Roman A
authors.initials: RA
authors.lastname: Barco
authors.affiliation: Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA.
authors.forename: David
authors.initials: D
authors.lastname: Emerson
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
authors.forename: Jason B
authors.initials: JB
authors.lastname: Sylvan
authors.affiliation: Bigelow Laboratory for Ocean Sciences, East Boothbay, Maine, USA.
authors.forename: Beth N
authors.initials: BN
authors.lastname: Orcutt
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
authors.forename: Myrna E
authors.initials: ME
authors.lastname: Jacobson Meyers
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Ramírez
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Zhong
authors.affiliation: Department of Biological Sciences, University of Southern California, Los Angeles, California, USA.
authors.forename: Katrina J
authors.initials: KJ
authors.lastname: Edwards
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D052837:Chemoautotrophic Growth; D007501:Iron / Q000378:metabolism*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D020560:Proteobacteria / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics
chemical_list: D001426:Bacterial Proteins; D007501:Iron