Fusion Proteins Containing Proteorhodopsin from Exiguobacterium sibiricum

Objective: To study the transport activity of bacterial rhodopsins, proteoliposomes with the same orientation of the protein molecules should be obtained. Methods: The genes of fusion proteins containing Exiguobacterium sibiricum proteorhodopsin (ESR) and various N-terminal soluble domains have been constructed. Results and Discussion: Effective synthesis in Escherichia coli cells was observed only in the case of fusion with chaperone Caf1M and maltose-binding protein MBP expressed as precursors with their own signal sequences. The study of the isolated MBP-ESR protein in micelles and proteoliposomes demonstrated formation and decay of the main photocycle intermediates at pH > 8. The photoelectric response of the fusion proteins Caf-ESR and MBP-ESR is comparable in amplitude to the wild-type ESR response, indicating their homogeneous orientation in the proteoliposome membrane. Conclusions: The obtained constructs can be used to create bacterial expression systems for various retinal proteins, ensuring their uniform incorporation into proteoliposomes.