Anabaena sensory rhodopsin: a photochromic color sensor at 2.0 A.
Microbial sensory rhodopsins are a family of membrane-embedded photoreceptors in prokaryotic and eukaryotic organisms. Structures of archaeal rhodopsins, which function as light-driven ion pumps or photosensors, have been reported. We present the structure of a eubacterial rhodopsin, which differs from those of previously characterized archaeal rhodopsins in its chromophore and cytoplasmic-side portions. Anabaena sensory rhodopsin exhibits light-induced interconversion between stable 13-cis and all-trans states of the retinylidene protein. The ratio of its cis and trans chromophore forms depends on the wavelength of illumination, thus providing a mechanism for a single protein to signal the color of light, for example, to regulate color-sensitive processes such as chromatic adaptation in photosynthesis. Its cytoplasmic half channel, highly hydrophobic in the archaeal rhodopsins, contains numerous hydrophilic residues networked by water molecules, providing a connection from the photoactive site to the cytoplasmic surface believed to interact with the receptor's soluble 14-kilodalton transducer.
Department of Molecular Biology and Biochemistry, University of California, Irvine, CA 92697, USA.
Lutz
L
Vogeley
Oleg A
OA
Sineshchekov
Vishwa D
VD
Trivedi
Jun
J
Sasaki
John L
JL
Spudich
Hartmut
H
Luecke
D017033:Anabaena / Q000737:chemistry*; D019843:Archaeal Proteins / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry; D001665:Binding Sites; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D018360:Crystallography, X-Ray; D003593:Cytoplasm / Q000737:chemistry; D006860:Hydrogen Bonding; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry; D008958:Models, Molecular; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D025603:Sensory Rhodopsins / Q000737:chemistry*; D014867:Water
D019843:Archaeal Proteins; D001426:Bacterial Proteins; D008051:Lipid Bilayers; D025603:Sensory Rhodopsins; D014867:Water