Functional expression of pharaonis phoborhodopsin in Escherichia coli

Pharaonis phoborhodopsin, the photoreceptor of the negative phototaxis of archaebacterial Natronobacterium pharaonis, was functionally expressed in the heterologous system of Escherichia coli. Flash-photolysis on a millisecond time scale indicated that the photochemical properties of ppR expressed in E. coli were the same as those of the native ppR in N. pharaonis. We concluded that the integral membrane protein ppR is correctly folded in vivo in the eubacterial E. coli membrane.