title: A multidisciplinary study of iron transport and storage in the marine green alga Tetraselmis suecica.
abstract: The iron uptake and storage systems of terrestrial/higher plants are now reasonably well understood with two basic strategies being distinguished: strategy I involves the induction of a Fe(III)-chelate reductase (ferrireductase) along with Fe(II) or Fe(III) 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 green alga Tetraselmis suecica. Short term radio-iron uptake studies indicate that iron is taken up by Tetraselmis in a time and concentration dependent manner consistent with an active transport process. Based on inhibitor and other studies it appears that a reductive-oxidative pathway such as that found in yeast and the green alga Chlamydomonas reinhardtii is likely. Upon long term exposure to (57)Fe we have been able, using a combination of Mössbauer and X-ray absorption spectroscopies, to identify three metabolites. The first exhibits Mössbauer parameters typical of a [Fe(4)S(4)](2+) cluster and which accounts for approximately 10% of the total intracellular iron pool. The second displays a spectrum typical of a [Fe(II)O(6)] system accounting for approximately 2% of the total pool. The largest component (ca. 85+%) consists of polymeric iron-oxo mineral species with parameters between that of the crystalline ferrihydrite core of animal ferritins and the amorphous hydrated ferric phosphate 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; D000460:Chlorophyta / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D008386:Marine Biology; D015204:Spectroscopy, Mossbauer; D056928:X-Ray Absorption Spectroscopy
chemical_list: D007501:Iron