The mitochondrial copper chaperone COX19 influences copper and iron homeostasis in arabidopsis
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The mitochondrial metallochaperone COX19 influences iron and copper responses highlighting a role of mitochondria in modulating metal homeostasis in Arabidopsis.
The mitochondrial copper chaperone COX19 participates in the biogenesis of cytochrome c oxidase (COX) in yeast and humans. In this work, we studied the function of COX19 in Arabidopsis thaliana, using plants with either decreased or increased COX19 levels. A fusion of COX19 to the red fluorescent protein localized to mitochondria in vivo, suggesting that Arabidopsis COX19 is a mitochondrial protein. Silencing of COX19 using an artificial miRNA did not cause changes in COX activity levels or respiration in plants grown under standard conditions. These amiCOX19 plants, however, showed decreased expression of the low-copper responsive miRNA gene MIR398b and an induction of the miR398 target CSD1 relative to wild-type plants. Plants with increased COX19 levels, instead, showed induction of MIR398b and other low-copper responsive genes. In addition, global transcriptional changes in rosettes of amiCOX19 plants resembled those observed under iron deficiency. Phenotypic analysis indicated that the roots of amiCOX19 plants show altered growth responses to copper excess and iron deficiency. COX activity levels and COX-dependent respiration were lower in amiCOX19 plants than in wild-type plants under iron deficiency conditions, suggesting that COX19 function is particularly important for COX assembly under iron deficiency. The results indicate that the mitochondrial copper chaperone COX19 has a role in regulating copper and iron homeostasis and responses in plants.
KeywordsArabidopsis thaliana Copper homeostasis COX19 Cytochrome c oxidase Iron homeostasis Mitochondria
Confocal laser scanning microscopy
Cytochrome c oxidase
Green fluorescent protein
Modified red fluorescent protein
Murashige and Skoog
Voltage dependent anion channel
This work was supported by Grants from Agencia Nacional de Promoción Científica y Tecnológica (ANPCyT, Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET, Argentina); and Universidad Nacional del Litoral (UNL, Argentina). EW, MAP and DHG are members of CONICET. LG and NM are fellows of the same Institution. NO was an undergraduate fellow of UNL. We thank Javier Palatnik for sending us the MIR398b reporter line and the pNB47 vector, Agustín Arce for help with microarray analysis, Iris Steinebrunner for help with CLSM, María Rosa Marano for the use of laboratory space, reagents and equipment during the work of LG in Rosario, and Pablo Manavella for the labeled miRNA probes.
DHG, EW and LG conceived and designed the experiments; LG, NM and NO performed the experiments and analyzed the data; MAP performed the ICP-MS determination of metal content; DHG wrote the paper; EW and LG contributed with the writing of the paper; all authors read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflicts of interest.
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