Snap-Tag™ Mediated Live Cell Labeling as an Alternative to GFP in Anaerobic Organisms

The protozoan human parasite Giardia intestinalis represents one of the earliest known branches of the eukaryotic lineage. Therefore its simple compartmental organization may hold answers as to how the complex eukaryotic endomembrane system has evolved and what early eukaryotes may have looked like. Using fluorescent protein technology to investigate compartmental trafficking and dynamics in this organism has been only partially successful, as GFP and its autofluorescent protein relatives need oxygenation in order to mature and become fluorescent. Giardia is a microaerotolerant parasite and tolerates only very low oxygen levels, which makes the use of autofluorescent proteins at the least very problematic. As an alternative to such reporters, SNAP-tag labeling is used here to label and visualize proteins in live Giardia parasites.