Structural and dynamic insights into SPDT for phosphorus allocation in rice

Area of Science:

• Plant Biology
• Structural Biology
• Biochemistry

Background:

• Phosphorus is vital for plant growth, absorbed as inorganic phosphate (Pi).
• Specialized transporters, like SULTR-like phosphorus distribution transporters (SPDTs), manage Pi distribution.
• SPDTs are key targets for enhancing crop nutrient use efficiency in sustainable agriculture.

Purpose of the Study:

• To determine the structural basis of Pi transport by rice SPDT.
• To elucidate the dynamic mechanism regulating SPDT activity and its interaction with the STAS domain.

Main Methods:

• Cryo-electron microscopy (cryo-EM) to obtain high-resolution structures of rice SPDT.
• Integrative structural analysis and single-molecule Förster resonance energy transfer (smFRET) to study transporter dynamics.

Main Results:

• Revealed an elevator-type transport mechanism involving a mobile Pi-binding core domain and a stationary gate domain.
• Identified specific residues and an electropositive vestibule crucial for Pi coordination and transport.
• Demonstrated the STAS domain acts as a bidirectional conformation-switch, regulating transporter states.

Conclusions:

• The study provides a detailed mechanistic blueprint of SPDT function.
• Understanding SPDT regulation offers opportunities for engineering phosphorus allocation in crops.
• Findings highlight conserved regulatory mechanisms across related transporter families for enhanced nutrient-use efficiency.