Rhodopsins: An Excitingly Versatile Protein Species for Research, Development and Creative Engineering.

The first member and eponym of the rhodopsin family was identified in the 1930s as the visual pigment of the rod photoreceptor cell in the animal retina. It was found to be a membrane protein, owing its photosensitivity to the presence of a covalently bound chromophoric group. This group, derived from vitamin A, was appropriately dubbed retinal.

Membrane matters: The impact of a nanodisc-bilayer or a detergent microenvironment on the properties of two eubacterial rhodopsins.

Multi-spanning membrane proteins usually require solubilization to allow proper purification and characterization, which generally impairs their structural and functional integrity. We have tested the efficacy of several commonly used detergents and membrane-mimicking nanodiscs with respect to solubilization, spectral properties, thermal stability and oligomeric profile of two membrane proteins from the eubacterial rhodopsin family, green proteorhodopsin (PR) and Gloeobacter violaceus rhodopsin (GR). Good solubilization was observed for the detergents TritonX-100 and dodecylphosphocholine (DPC), but DPC in particular strongly affected the thermal stability of PR and especially GR.

Photoreaction Dynamics of Red-Shifting Retinal Analogues Reconstituted in Proteorhodopsin.

Microbial rhodopsins constitute a key protein family in optobiotechnological applications such as optogenetics and voltage imaging. Spectral tuning of rhodopsins into the deep-red and near-infrared spectral regions is of great demand in such applications because more bathochromic light into the near-infrared range penetrates deeper in living tissue. Recently, retinal analogues have been successfully used in ion transporting and fluorescent rhodopsins to achieve red-shifted absorption, activity, and emission properties.

Functional Expression of Rhodopsin in PSI-Less sp. PCC6803.

The approach of providing an oxygenic photosynthetic organism with a cyclic electron transfer system, i.e., a far-red light-driven proton pump, is widely proposed to maximize photosynthetic efficiency via expanding the absorption spectrum of photosynthetically active radiation.

Redshifted and Near-infrared Active Analog Pigments Based upon Archaerhodopsin-3.

Archaerhodopsin-3 (AR3) is a member of the microbial rhodopsin family of hepta-helical transmembrane proteins, containing a covalently bound molecule of all-trans retinal as a chromophore. It displays an absorbance band in the visible region of the solar spectrum (λmax 556 nm) and functions as a light-driven proton pump in the archaeon Halorubrum sodomense. AR3 and its mutants are widely used in neuroscience as optogenetic neural silencers and in particular as fluorescent indicators of transmembrane potential.