Proteorhodopsin.
Proteorhodopsins are the most abundant retinal based photoreceptors and their phototrophic function might be relevant in marine ecosystems. Here, we describe their remarkable molecular properties with a special focus on the green absorbing variant. Its distinct features include a high pKa value of the primary proton acceptor stabilized through an interaction with a conserved histidine, a long-range interaction between the cytoplasmic EF loop and the chromophore entailing a particular mode of color tuning and a variable proton pumping vectoriality with complex voltage-dependence. The proteorhodopsin family represents a profound example for structure-function relationships. Especially the development of a biophysical understanding of green proteorhodopsin is an excellent example for the unique opportunities offered by a combined approach of advanced spectroscopic and electrophysiological methods. This article is part of a Special Issue entitled: Retinal Proteins-You can teach an old dog new tricks.
Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany. Electronic address: christian.bamann@biophys.mpg.de.
Christian
C
Bamann
Max Planck Institute of Biophysics, Max-von-Laue Straße 3, 60438 Frankfurt am Main, Germany.
Ernst
E
Bamberg
Johann Wolfgang Goethe University, Institute for Physical and Theoretical Chemistry, Max-von-Laue Straße 7, 60438 Frankfurt am Main, Germany.
Josef
J
Wachtveitl
Johann Wolfgang Goethe University, Institute for Biophysical Chemistry & Centre for Biomolecular Magnetic Resonance, Max-von-Laue Straße 9, 60438 Frankfurt am Main, Germany.
Clemens
C
Glaubitz
D000595:Amino Acid Sequence; D000818:Animals; D006639:Histidine / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D017136:Ion Transport; D008027:Light; D008958:Models, Molecular; D008969:Molecular Sequence Data; D018408:Patch-Clamp Techniques; D011487:Protein Conformation; D020560:Proteobacteria / Q000737:chemistry / Q000502:physiology; D011522:Protons; D012172:Retinaldehyde / Q000737:chemistry* / Q000378:metabolism; D012243:Rhodopsin / Q000737:chemistry* / Q000378:metabolism; D025604:Rhodopsins, Microbial; D013329:Structure-Activity Relationship; D014981:Xenopus / Q000502:physiology
D011522:Protons; D025604:Rhodopsins, Microbial; C413548:proteorhodopsin; D006639:Histidine; D012243:Rhodopsin; D012172:Retinaldehyde
Charge transfer; Electrophysiology; NMR spectroscopy; Photocycle; Photoisomerization