Arabidopsis PROTODERMAL FACTOR2 binds lysophosphatidylcholines and transcriptionally regulates phospholipid metabolism

作者：Izabela Wojciechowska, Thiya Mukherjee, Patrick Knox‐Brown, Xueyun Hu, Aashima Khosla, Bibek Subedi, Usama Ahmad, Graham L. Mathews, Ashley A. Panagakis, Kyle A. Thompson, Sophie T. Peery, Jagoda Szlachetko, Anja Thalhammer, Dirk K. Hincha, Aleksandra Skirycz, Kathrin Schrick · 发表于：New Phytologist · 年份：2024 · DOI：10.1111/nph.19917 · 被引用次数：16 · 研究领域：Photosynthetic Processes and Mechanisms、Plant Molecular Biology Research、Plant Reproductive Biology

Plant homeodomain leucine zipper IV (HD-Zip IV) transcription factors (TFs) contain an evolutionarily conserved steroidogenic acute regulatory protein (StAR)-related lipid transfer (START) domain. While the START domain is required for TF activity, its presumed role as a lipid sensor is not clear. Here we used tandem affinity purification from Arabidopsis cell cultures to demonstrate that PROTODERMAL FACTOR2 (PDF2), a representative member that controls epidermal differentiation, recruits lysophosphatidylcholines (LysoPCs) in a START-dependent manner. Microscale thermophoresis assays confirmed that a missense mutation in a predicted ligand contact site reduces lysophospholipid binding. We additionally found that PDF2 acts as a transcriptional regulator of phospholipid- and phosphate (Pi) starvation-related genes and binds to a palindromic octamer with consensus to a Pi response element. Phospholipid homeostasis and elongation growth were altered in pdf2 mutants according to Pi availability. Cycloheximide chase experiments revealed a role for START in maintaining protein levels, and Pi starvation resulted in enhanced protein destabilization, suggesting a mechanism by which lipid binding controls TF activity. We propose that the START domain serves as a molecular sensor for membrane phospholipid status in the epidermis. Our data provide insights toward understanding how the lipid metabolome integrates Pi availability with gene expression.