Structural and dynamic insights into phosphate uptake by PHT1 transporter in rice

Abstract

Phosphorus is an essential macronutrient for plants, primarily absorbed from the soil as inorganic phosphate (Pi) through root-located Pi transporters. Despite decades of research into these transporters as targets for developing Pi-efficient crops, their mechanisms for Pi import remain poorly understood. Here, we present the cryo-EM structures of the rice Pi importer OsPHT1;11 in both Pi-bound and unbound forms, characterize its conformational dynamics, and reveal how these dynamics contribute to its transport function. Pi is recognized through conserved residues found in plants, with its translocation facilitated by a typical alternating-access mechanism. SmFRET analyses reveal that this transporter undergoes dynamic conformational changes, which are differentially linked to its Pi transport capability, with a predominance of extracellular open conformations favoring Pi transport, while more populated intracellular open conformations hinder it. These findings provide insights into Pi uptake in plants and offer a foundation for designing genetically modified crops with improved phosphate efficiency.