Mechanism of phosphate sensing and signaling revealed by rice SPX1-PHR2 complex structure.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34857773.
- Also identified by DOI 10.1038/s41467-021-27391-5 and PMC identifier 8639918.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
Phosphate, a key plant nutrient, is perceived through inositol polyphosphates (InsPs) by SPX domain-containing proteins. SPX1 an inhibit the PHR2 transcription factor to maintain Pi homeostasis. How SPX1 recognizes an InsP molecule and represses transcription activation by PHR2 remains unclear. Here we show that, upon binding InsP<sub>6</sub>, SPX1 can disrupt PHR2 dimers and form a 1:1 SPX1-PHR2 complex. The complex structure reveals that SPX1 helix α1 can impose a steric hindrance when interacting with the PHR2 dimer. By stabilizing helix α1, InsP<sub>6</sub> allosterically decouples the PHR2 dimer and stabilizes the SPX1-PHR2 interaction. In doing so, InsP<sub>6</sub> further allows SPX1 to engage with the PHR2 MYB domain and sterically block its interaction with DNA. Taken together, our results suggest that, upon sensing the surrogate signals of phosphate, SPX1 inhibits PHR2 via a dual mechanism that attenuates dimerization and DNA binding activities of PHR2.
Medical subject headings
- Arabidopsis
- Arabidopsis Proteins
- DNA, Plant
- Inositol Phosphates
- Nuclear Proteins
- Oryza