Rational engineering of lipid-binding probes via high-throughput protein-lipid interaction screening

Lipid-binding domains, originally isolated from natural proteins, are useful tools essential for analyzing membrane lipids in cells, and their applications are varied. Yet, there is no general strategy for engineering lipid-binding domains. Here, we present a robust method for monitoring protein-lipid interactions, named the Cell surface Liposome Binding (CLiB) assay. Using this technique, we isolated high-affinity lipid-binding domains and nanobodies that preferentially bind to phosphatidylinositol phosphates. Furthermore, by combining the CLiB assay with next-generation sequencing, allowing the analysis of more than 10,000 clones in parallel, we identified novel variants with enhanced binding to phosphatidylinositol phosphates and uncovered a common structural feature: a positively charged pocket necessary for binding, formed by the three loop regions. This study opens a new avenue for the rational design and generation of lipid-binding probes on demand.