An improved TurboID-based proximity labeling pipeline in C. elegans by biochemical depletion of endogenously biotinylated carboxylases

To review an improved proximity-labeling strategy that uses the improved E. coli biotin ligase TurboID to characterize C. elegans protein complexes, the interactome of a presynaptic active zone protein, ELKS-1, was analyzed as proof of principle. A significant constraint on the sensitivity of TurboID-based proximity labeling is the presence of abundant, endogenously biotinylated proteins that take up bandwidth in the mass spectrometer, notably carboxylases that use biotin as a co-factor. We developed ways to remove these carboxylases prior to streptavidin purification and mass spectrometry, by engineering their corresponding genes to add a C-terminal His10 tag. This allows us to deplete them from C. elegans lysates using immobilized metal affinity chromatography (IMAC).