|
IRON MAN interacts with BRUTUS to maintain iron homeostasis in Arabidopsis
| First Author: |
Li Y; Lu CK; Li CY |
| Abstract: |
IRON MAN (IMA) peptides, a family of small peptides, control iron (Fe) transport in plants, but their roles in Fe signaling remain unclear. BRUTUS (BTS) is a potential Fe sensor that negatively regulates Fe homeostasis by promoting the ubiquitin-mediated degradation of bHLH105 and bHLH115, two positive regulators of the Fe deficiency response. Here, we show that IMA peptides interact with BTS. The C-terminal parts of IMA peptides contain a conserved BTS interaction domain (BID) that is responsible for their interaction with the C terminus of BTS. Arabidopsis thaliana plants constitutively expressing IMA genes phenocopy the bts-2 mutant. Moreover, IMA peptides are ubiquitinated and degraded by BTS. bHLH105 and bHLH115 also share a BID, which accounts for their interaction with BTS. IMA peptides compete with bHLH105/bHLH115 for interaction with BTS, thereby inhibiting the degradation of these transcription factors by BTS. Genetic analyses suggest that bHLH105/bHLH115 and IMA3 have additive roles and function downstream of BTS. Moreover, the transcription of both BTS and IMA3 is activated directly by bHLH105 and bHLH115 under Fe-deficient conditions. Our findings provide a conceptual framework for understanding the regulation of Fe homeostasis: IMA peptides protect bHLH105/bHLH115 from degradation by sequestering BTS, thereby activating the Fe deficiency response. |
| Contact the author: |
Liang G |
| Page Number: |
e2109063118 |
| Issue: |
39 |
| Subject: |
|
| Impact Factor: |
11.205 |
| Authors units: |
|
| PubYear: |
Sep 2021 |
| Volume: |
118 |
| Publication Name: |
Proceedings of the National Academy of Sciences of the United States of America |
| The full text link: |
|
| ISSN: |
|
| Download: |
Download Address |
|
|
|
|
