PDBsum entry 6mqw

Lipid binding protein

PDB id: 6mqw

Contents

Protein chain

137 a.a.

Ligands

RET

Waters ×54

References listed in PDB file

Key reference

• Title: Mimicking microbial rhodopsin isomerization in a single crystal.
• Authors: A.Ghanbarpour, M.Nairat, M.Nosrati, E.M.Santos, C.Vasileiou, M.Dantus, B.Borhan, J.H.Geiger.
• Ref.: J Am Chem Soc, 2019, 141, 1735-1741. [DOI no: 10.1021/jacs.8b12493]
• PubMed id: 30580520

Abstract

Bacteriorhodopsin represents the simplest, and possibly most abundant, phototropic system requiring only a retinal-bound transmembrane protein to convert photons of light to an energy-generating proton gradient. The creation and interrogation of a microbial rhodopsin mimic, based on an orthogonal protein system, would illuminate the design elements required to generate new photoactive proteins with novel function. We describe a microbial rhodopsin mimic, created using a small soluble protein as a template, that specifically photoisomerizes all- trans to 13- cis retinal followed by thermal relaxation to the all- trans isomer, mimicking the bacteriorhodopsin photocycle, in a single crystal. The key element for selective isomerization is a tuned steric interaction between the chromophore and protein, similar to that seen in the microbial rhodopsins. It is further demonstrated that a single mutation converts the system to a protein photoswitch without chromophore photoisomerization or conformational change.