見えなかった膜脂質が見える―新技術CLiBアッセイで膜脂質可視化ツールを開発

2026-07-06 東京大学

図1 生体膜の膜脂質環境は多様である

＜関連情報＞

• https://www.iis.u-tokyo.ac.jp/ja/news/5099/
• https://www.nature.com/articles/s41556-026-01996-8

細胞表面リポソーム結合（CLiB）により、ハイスループットスクリーニングを介した脂質結合プローブの設計が可能になる Cell surface liposome binding (CLiB) allows lipid-binding probe engineering via high-throughput screening

Taki Nishimura,Kotaro Tsuboyama,Yuki Nakagaki,Shiou-Ling Lu,Yuki Ishino,Nozomu Kono,Takeshi Noda,Eiji Yamamoto & Noboru Mizushima
Nature Cell Biology  Published:02 July 2026
DOI:https://doi.org/10.1038/s41556-026-01996-8

Abstract

Lipid-binding domains, traditionally isolated from natural proteins, are essential tools for probing membrane lipid dynamics and specialized cellular compartments. Despite diverse applications, a general strategy for their engineering remains elusive. Here we present a robust and high-throughput method for monitoring protein–lipid interactions, named the cell surface liposome binding (CLiB) assay. Using the assay, we conducted directed evolution of the PX domain from SnxA, isolating high-affinity variants specific for phosphatidylinositol 3,5-bisphosphate (PI(3,5)P₂). Combining the CLiB assay with next-generation sequencing enabled parallel analysis of >6,000 clones, comprehensively identifying key residues critical for lipid binding. An engineered variant, PX-SnxA^GV, functioned as a lipid biosensor in yeast and mammalian cells, visualizing PI(3,5)P₂-enriched membrane subdomains upon hyperosmotic shock and during microautophagy, thereby suggesting localized PI(3,5)P₂ synthesis within spatially restricted regions. This study provides a framework for on-demand generation of lipid-binding probes, facilitating the discovery of membrane compartments characterized by unique lipid compositions.