title: Iron transport and storage in the coccolithophore: Emiliania huxleyi.
abstract: Iron is an essential element for all living organisms due to its ubiquitous role in redox and other enzymes, especially in the context of respiration and photosynthesis. The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood with two basic strategies for iron uptake being distinguished: strategy I plants use a mechanism involving soil acidification and induction of Fe(III)-chelate reductase (ferrireductase) and Fe(II) transporter proteins while strategy II plants have evolved sophisticated systems based on high-affinity, iron specific, binding compounds called phytosiderophores. In contrast, there is little knowledge about the corresponding systems in marine plant-like lineages. Herein we report a study of the iron uptake and storage mechanisms in the coccolithophore Emiliania huxleyi. Short term radio-iron uptake studies indicate that iron is taken up by Emiliania in a time and concentration dependent manner consistent with an active transport process. Based on inhibitor studies it appears that iron is taken up directly as Fe(iii). However if a reductive step is involved the Fe(II) must not be accessible to the external environment. Upon long term exposure to (57)Fe we have been able, using a combination of Mössbauer and XAS spectroscopies, to identify a single metabolite which displays spectral features similar to the phosphorus-rich mineral core of bacterial and plant ferritins.
authors.affiliation: Department of Chemistry and Biochemistry, San Diego State University, San Diego CA, 92182-1030, USA.
authors.forename: Andrej
authors.initials: A
authors.lastname: Hartnett
authors.forename: Lars H
authors.initials: LH
authors.lastname: Böttger
authors.forename: Berthold F
authors.initials: BF
authors.lastname: Matzanke
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Carrano
mesh_terms: D001692:Biological Transport; D058087:Haptophyta / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism*; D007501:Iron / Q000737:chemistry* / Q000378:metabolism*; D007503:Iron Isotopes / Q000737:chemistry / Q000378:metabolism; D033862:Iron-Binding Proteins; D008565:Membrane Proteins; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry / Q000378:metabolism; D013057:Spectrum Analysis
chemical_list: D007503:Iron Isotopes; D033862:Iron-Binding Proteins; D008565:Membrane Proteins; D007501:Iron; D010088:Oxidoreductases