Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme

Ádám Solti, Brigitta Müller, Viktória Czech, E. Sárvári, F. Fodor

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

Iron (Fe) has an essential role in the biosynthesis of chlorophylls and redox cofactors, and thus chloroplast iron uptake is a process of special importance. The chloroplast ferric chelate oxidoreductase (cFRO) has a crucial role in this process but it is poorly characterized. To study the localization and mechanism of action of cFRO, sugar beet (Beta vulgaris cv Orbis) chloroplast envelope fractions were isolated by gradient ultracentrifugation, and their purity was tested by western blotting against different marker proteins. The ferric chelate reductase (FCR) activity of envelope fractions was studied in the presence of NAD(P)H (reductants) and FAD coenzymes. Reduction of Fe(III)-ethylenediaminetetraacetic acid was monitored spectrophotometrically by the Fe(II)-bathophenanthroline disulfonate complex formation. FCR activity, that is production of free Fe(II) for Fe uptake, showed biphasic saturation kinetics, and was clearly associated only to chloroplast inner envelope (cIE) vesicles. The reaction rate was > 2.5 times higher with NADPH than with NADH, which indicates the natural coenzyme preference of cFRO activity and its dependence on photosynthesis. FCR activity of cIE vesicles isolated from Fe-deficient plants also showed clear biphasic kinetics, where the KM of the low affinity component was elevated, and thus this component was down-regulated.

Original languageEnglish
Pages (from-to)920-928
Number of pages9
JournalNew Phytologist
Volume202
Issue number3
DOIs
Publication statusPublished - 2014

Fingerprint

oxidoreductases
chelates
Chloroplasts
Oxidoreductases
chloroplasts
Enzymes
enzymes
Beta vulgaris
coenzymes
NAD (coenzyme)
Coenzymes
NAD
Iron
iron
uptake mechanisms
kinetics
Flavin-Adenine Dinucleotide
reducing agents
ultracentrifugation
Ultracentrifugation

Keywords

  • Chloroplast envelope membranes
  • Ferric chelate oxidoreductase
  • Ferric chelate reductase activity
  • Iron deficiency
  • Iron uptake

ASJC Scopus subject areas

  • Plant Science
  • Physiology
  • Medicine(all)

Cite this

Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme. / Solti, Ádám; Müller, Brigitta; Czech, Viktória; Sárvári, E.; Fodor, F.

In: New Phytologist, Vol. 202, No. 3, 2014, p. 920-928.

Research output: Contribution to journalArticle

Solti, Ádám ; Müller, Brigitta ; Czech, Viktória ; Sárvári, E. ; Fodor, F. / Functional characterization of the chloroplast ferric chelate oxidoreductase enzyme. In: New Phytologist. 2014 ; Vol. 202, No. 3. pp. 920-928.
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