Enzymatic labeling of bacterial proteins for live-cell super-resolution imaging

Mol. probes that illuminate the subcellular organization of prokaryotic organisms are essential for our understanding of the biol. world. We describe here a strategy for labeling bacterial proteins in situ with azido fatty acids using the enzyme N-myristoyltransferase. Cell-permeant photoswitchable fluorescent dyes are conjugated to target proteins through means of strain-promoted azide-alkyne cycloaddn. to enable super-resoln. imaging in live Escherichia coli cells. We demonstrate the method by labeling and imaging bacterial chemotaxis proteins and cell division proteins. The method provides a general framework for live-cell protein imaging with nanometer resoln.