Figure 2
Functional heterologous expression of proteorhodopsin in E. coli. (A) Color-shift by expression of proteorhodopsin. Left sample: E. coli BL21(DE3)/pACYC-RDS (proteorhodopsin expression & retinal synthesis), right sample: wild-type E. coli BL21(DE3). (B) Absorption spectra of the membrane of E. coli expressing proteorhodopsin alone. Membrane fractions in 50 mM Tris-Cl (pH 8.0) and 5 mM MgCl2 were mixed with 20 μM all-trans-retinal. Spectra were measured every 10 min for 30 min.