Cellular Labeling of Phosphatidylserine Using Clickable Serine Probes

Phosphatidylserine (PS) is a key lipid that plays important roles in disease-related biological processes, and therefore, the means to track PS in live cells are invaluable. Herein, we describe the metabolic labeling of PS in Saccharomyces cerevisiae cells using analogues of serine, a PS precursor, derivatized with azide moieties at either the amino (N-l-SerN3) or carbonyl (C-l-SerN3) groups. The conservative click tag modification enabled these compounds to infiltrate normal lipid biosynthetic pathways, thereby producing tagged PS molecules as supported by mass spectrometry studies, thin-layer chromatography (TLC) analysis, and further derivatization with fluorescent reporters via click chemistry to enable imaging in yeast cells. This approach shows strong prospects for elucidating the complex biosynthetic and trafficking pathways involving PS.