Copper Regulator CITF1 Crosstalks with Iron Regulator FIT in Arabidopsis thaliana

Copper and iron are essential micronutrients for plants. They are vital for biological processes such as photosynthesis but can be toxic when over-accumulated. Thus, plants have developed sophisticated mechanisms to maintain copper and iron homeostasis. Studies based on Arabidopsis thaliana show that COPPER DEFICIENCY-INDUCED TRANSCRIPTION FACTOR 1 (CITF1) plays an important role in copper deficiency response by upregulating copper uptake genes COPT2, FRO4, and FRO5. In regards to iron, FE-DEFICIENCY-INDUCED TRANSCRIPTION FACTOR (FIT) is a regulatory hub that controls the transcriptional iron deficiency response. Recently, we found that FIT interacts with CITF1 in two in vivo systems, including yeast two-hybrid assays and co-immunoprecipitation analysis. From there, we wanted to assess the stability of the CITF1-FIT complex. A CHX/MG132 assay was performed in the FIT-GFP transgenic lines co-expressed with and without CITF1 to assess protein accumulation over time without de novo protein synthesis or proteasomal degradation. We observed that FIT’s turnover rate decreases when it can form a complex with CITF1. Furthermore, both FIT and CITF1 are stabilized by copper deficiency. Finally, we found that both CITF1 and FIT are required for the upregulation of COPT2, FRO4, and FRO5 under copper deficiency. Overall, this work demonstrates that copper deficiency stabilizes the FIT-CITF1 complex, suggesting its importance in the copper deficiency response in A. thaliana.

My time in the Vatamaniuk lab through the BTI REU has been nothing short of incredible. Going in, I knew I wanted to be a plant scientist, but didn’t know if I had the mental strength to continue my journey onto graduate school and beyond. This proved to me that I did. As my mentor Ju-Chen and I worked together through our project, I felt myself growing every week. I became more confident in my ability to perform more complicated procedures like western blotting and was rewarded with good results that contributed to an important area of research. At times, it was hard to look forward when something had gone wrong or I didn’t feel confident enough to continue, but now, thanks to the support of Ju-Chen and the rest of the Vatamaniuk lab, I am ready to continue my journey to be a scientist.