Structure and differential expression of the four members of the Arabidopsis thaliana ferritin gene family

Abstract

Four ferritin genes are found within the complete sequence of the Arabidopsis thaliana genome. All of them are expressed and their corresponding cDNA species have been cloned. The polypeptide sequences deduced from these four genes confirm all the properties of the ferritin subunits described so far, non-exhaustively, from various plant species. All are predicted to be targeted to the plastids, which is consistent with the existence of a putative transit peptide at their N-terminal extremity. They also all possess a conserved extension peptide in the mature subunit. Specific residues for ferroxidase activity and iron nucleation, which are found respectively in H-type or L-type ferritin subunits in animals, are both conserved within each of the four A. thaliana ferritin polypeptides. In addition, the hydrophilic nature of the plant ferritin E-helix is conserved in the four A. thaliana ferritin subunits. Besides this strong structural conservation, the four genes are differentially expressed in response to various environmental signals, and during the course of plant growth and development. AtFer1 and AtFer3 are the two major genes expressed in response to treatment with an iron overload. Under our experimental conditions, AtFer4 is expressed with different kinetics and AtFer2 is not responsive to iron. H2O2 activates the expression of AtFer1 and, to a smaller extent, AtFer3. Abscisic acid promotes the expression of only AtFer2, which is consistent with the observation that this is the only gene of the four to be expressed in seeds, whereas AtFer1, AtFer4 and AtFer3 are expressed in various vegetative organs but not in seeds.

Transcriptional Characterization of a Widely-Used Grapevine Rootstock Genotype under Different Iron-Limited Conditions

“…Ferritins are a class of ubiquitous proteins, generally located in chloroplast and mitochondria, which are involved in iron storage and chelation (Petit et al, 2001) and prevent the generation of ROS due to Fe oxidation (Ravet et al, 2009). In the light of this, their down-regulation is most likely due to the lower content of Fe in the −Fe and FeBic samples.…”

Iron Uptake and Transport in Plants: The Good, the Bad, and the Ionome

“…Arabidopsis has four ferritin genes, of which only FER2 is expressed in developing seeds, and during germination. 110 Accordingly, FER2 is the only ferritin up-regulated in response to the plant hormone abscisic acid (ABA). The fer2 loss of function mutant does not affect Fe accumulation or seed viability under normal conditions; in fact, ferritin was estimated to account for only 5% of total seed Fe 104.…”

“…In Arabidopsis FER1, FER2, and FER3 are predicted to localize to the plastid; FER4 is predicted to localize to the mitochondria, or be dual targeted to both organelles 110. The roles of the ferritin paralogs is differentiated by localization and regulation: FER2 is only expressed in the seeds, while the other three ferritins are expressed in the shoots and flowers, in addition to FER1 expression in the roots 110.…”

“…The roles of the ferritin paralogs is differentiated by localization and regulation: FER2 is only expressed in the seeds, while the other three ferritins are expressed in the shoots and flowers, in addition to FER1 expression in the roots 110. Additionally, the expression of the three non-seed ferritins increases in response to high Fe levels, whereas the seed FER2 is expressed in response to the plant hormone ABA 110. Ferritins appear to buffer Fe levels, and sequester excess free Fe to prevent oxidative stress 104.…”

Overexpression of wheat ferritin gene TaFER-5B enhances tolerance to heat stress and other abiotic stresses associated with the ROS scavenging

“…In plants, ferritin gene expression was induced in response to drought, salt, cold, heat and pathogen infection [9, 14]. Arabidopsis ferritin genes were induced by treatment with H 2 O 2 , iron and abscisic acid (ABA); however, not all four AtFER genes were induced [15]. Ferritin was up-regulated in response to drought in the SSH (Suppression Subtractive Hybridization) cDNA library of soybean nodules [16].…”