PT  - JOURNAL ARTICLE
AU  - Leah J. Kim
AU  - Kaitlyn M. Tsuyuki
AU  - Fengling Hu
AU  - Emily Y. Park
AU  - Jingwen Zhang
AU  - Jennifer Gallegos Iraheta
AU  - Ju-Chen Chia
AU  - Rong Huang
AU  - Avery E. Tucker
AU  - Madeline Clyne
AU  - Claire Castellano
AU  - Angie Kim
AU  - Daniel D. Chung
AU  - Christopher T. DaVeiga
AU  - Elizabeth M. Parsons
AU  - Olena K. Vatamaniuk
AU  - Jeeyon Jeong
TI  - Ferroportin 3 is a dual-targeted mitochondrial/chloroplast iron exporter necessary for iron homeostasis in Arabidopsis
AID  - 10.1101/2020.07.15.203646
DP  - 2020 Jan 01
TA  - bioRxiv
PG  - 2020.07.15.203646
4099  - http://biorxiv.org/content/early/2020/11/07/2020.07.15.203646.short
4100  - http://biorxiv.org/content/early/2020/11/07/2020.07.15.203646.full
AB  - Mitochondria and chloroplasts are organelles with high iron demand that are particularly susceptible to iron-induced oxidative stress. Despite the necessity of strict iron regulation in these organelles, much remains unknown about mitochondrial and chloroplast iron transport in plants. Here, we propose that Arabidopsis Ferroportin 3 (FPN3) is an iron exporter dual-targeted to mitochondria and chloroplasts. FPN3 is expressed in shoots regardless of iron conditions, but its transcripts accumulate under iron deficiency in roots. fpn3 mutants cannot grow as well as wild type under iron-deficient conditions and shoot iron levels are reduced in fpn3 mutants compared to wild type. ICP-MS measurements show that iron levels in the mitochondria and chloroplasts are increased relative to wild type, consistent with the proposed role of FPN3 as a mitochondrial/plastid iron exporter. In iron deficient fpn3 mutants, abnormal mitochondrial ultrastructure was observed, whereas chloroplast ultrastructure was not affected, implying that FPN3 plays a critical role in the mitochondria. Overall, our study suggests that FPN3 is essential for optimal iron homeostasis.Significance statement Iron homeostasis must be tightly controlled in the mitochondria and chloroplasts, but iron trafficking in these organelles is not fully understood. Our work suggests that FPN3 is an iron exporter required for maintaining proper iron levels in mitochondria and chloroplasts. Furthermore, FPN3 is necessary for the optimal growth and normal mitochondrial ultrastructure under iron deficiency. This study reveals the physiological role of FPN3 and advances our understanding of iron regulation in mitochondria and chloroplasts.Competing Interest StatementThe authors have declared no competing interest.