TY - JOUR

T1 - AtFer4 ferritin is a determinant of iron homeostasis in Arabidopsis thaliana heterotrophic cells

AU - Tarantino, Delia

AU - Santo, Nadia

AU - Morandini, Piero

AU - Casagrande, Francesca

AU - Braun, Hans Peter

AU - Heinemeyer, Jesco

AU - Vigani, Gianpiero

AU - Soave, Carlo

AU - Murgia, Irene

N1 - Funding information: We thank Valentina Vazzola for help during the cultivation of mutant lines, Ralf Berndt Klösgen and coworkers for communicating unpublished data, Marcello Iriti for the DAB staining and Nicoletta Beffagna for allowing access to all her laboratory equipment, help during mitochondria purification and for her manuscript revision. Janneke Balk kindly donated NAD9 and AOX antibodies to Gianpiero Vigani. We are grateful to Jean Francois Briat and to Frederic Gaymard for the anti-ATFER1 polyclonal antibody and for their valuable comments on the manuscript. This work was supported by MIUR [PRIN 2006, prot. Nr. 2006058818 and PRIN 2008, prot. Nr. 20084XTFBC]. D. Tarantino was partially supported by INGENIO grants.

PY - 2010/8/17

Y1 - 2010/8/17

N2 - In plants, the iron storage protein ferritin can be targeted to both chloroplasts and mitochondria. To investigate the role of Arabidopsis ATFER4 ferritin in mitochondrial iron trafficking, atfer4-1 and atfer4-2 mutant knock-outs for the AtFer4 gene were grown in heterotrophic suspension cultures. Both mutants showed altered cell size and morphology, reduced viability, higher H2O2 content and reduced O2 consumption rates when compared to wt. Although no reduction in total ferritin or in mitochondrial ferritin was observed in atfer4 mutants, total iron content increased in atfer4 cells and in atfer4 mitochondria. Transcript correlation analysis highlighted a partial inverse relationship between the transcript levels of the mitochondrial ferric reductase oxidase FRO3, putatively involved in mitochondrial iron import/export, and AtFer4. Consistent with this, FRO3 transcript levels were higher in atfer4 cells. We propose that the complex molecular network maintaining Fe cellular homeostasis requires, in Arabidopsis heterotrophic cells, a proper balance of the different ferritin isoforms, and that alteration of this equilibrium, such as that occurring in atfer4 mutants, is responsible for an altered Fe homeostasis resulting in a change of intraorganellar Fe trafficking.

AB - In plants, the iron storage protein ferritin can be targeted to both chloroplasts and mitochondria. To investigate the role of Arabidopsis ATFER4 ferritin in mitochondrial iron trafficking, atfer4-1 and atfer4-2 mutant knock-outs for the AtFer4 gene were grown in heterotrophic suspension cultures. Both mutants showed altered cell size and morphology, reduced viability, higher H2O2 content and reduced O2 consumption rates when compared to wt. Although no reduction in total ferritin or in mitochondrial ferritin was observed in atfer4 mutants, total iron content increased in atfer4 cells and in atfer4 mitochondria. Transcript correlation analysis highlighted a partial inverse relationship between the transcript levels of the mitochondrial ferric reductase oxidase FRO3, putatively involved in mitochondrial iron import/export, and AtFer4. Consistent with this, FRO3 transcript levels were higher in atfer4 cells. We propose that the complex molecular network maintaining Fe cellular homeostasis requires, in Arabidopsis heterotrophic cells, a proper balance of the different ferritin isoforms, and that alteration of this equilibrium, such as that occurring in atfer4 mutants, is responsible for an altered Fe homeostasis resulting in a change of intraorganellar Fe trafficking.

KW - Arabidopsis

KW - Cell death

KW - Ferritin

KW - Iron

KW - Mitochondria

UR - http://www.scopus.com/inward/record.url?scp=78149412309&partnerID=8YFLogxK

U2 - 10.1016/j.jplph.2010.06.020

DO - 10.1016/j.jplph.2010.06.020

M3 - Article

C2 - 20724023

AN - SCOPUS:78149412309

VL - 167

SP - 1598

EP - 1605

JO - Journal of plant physiology

JF - Journal of plant physiology

SN - 0176-1617

IS - 18

ER -