title: AtFer4 ferritin is a determinant of iron homeostasis in Arabidopsis thaliana heterotrophic cells.
abstract: 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.
authors: Dipartimento di Biologia, Università degli Studi di Milano, via Celoria 26, Italy.
authors: Delia
authors: D
authors: Tarantino
authors: Nadia
authors: N
authors: Santo
authors: Piero
authors: P
authors: Morandini
authors: Francesca
authors: F
authors: Casagrande
authors: Hans-Peter
authors: HP
authors: Braun
authors: Jesco
authors: J
authors: Heinemeyer
authors: Gianpiero
authors: G
authors: Vigani
authors: Carlo
authors: C
authors: Soave
authors: Irene
authors: I
authors: Murgia
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002470:Cell Survival / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D005293:Ferritins / Q000235:genetics / Q000378:metabolism*; D052836:Heterotrophic Processes; D006706:Homeostasis / Q000235:genetics / Q000502:physiology; D007501:Iron / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D029681:Arabidopsis Proteins; D005293:Ferritins; D007501:Iron