In situ 19F NMR studies of an E. coli membrane protein

In this report, 19F spin incorporation in a specific site of a specific membrane protein in E. coli was accomplished via trifluoromethyl-phenylalanine (19F-tfmF). Site-specific 19F chemical shifts and longitudinal relaxation times of diacylglycerol kinase (DAGK), an E. coli membrane protein, were measured in its native membrane using in situ magic angle spinning (MAS) solid state nuclear magnetic resonance (NMR). Comparing with solution NMR data of the purified DAGK in detergent micelles, the in situ MAS-NMR data illustrated that 19F chemical shift values of residues at different membrane protein locations were influenced by interactions between membrane proteins and their surrounding lipid or lipid mimic environments, while 19F side chain longitudinal relaxation values were probably affected by different interactions of DAGK with planar lipid bilayer versus globular detergent micelles.