Figure 8.

Model for BTS protein stability and function. A, BTS is transcriptionally induced by iron deficiency along with bHLH transcription factors PYE and PYEL. Under low-iron conditions, BTS protein is more stable and regulates PYEL/PYE regulatory activity through its E3 ligase activity to modulate and fine-tune PYEL/PYE-mediated iron deficiency response in plants. B, Upon recovery of iron, transcriptional induction of BTS, PYE, and PYEL decreases. Elevated levels of iron are sensed through the HHE domains, altering BTS conformation and stability. This response results in the proteolysis of BTS protein, thereby further reducing the iron-responsive E3 ligase capacity of the cells.