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Sensory Rhodopsin I and Sensory Rhodopsin II Form Trimers of Dimers in Complex with their Cognate Transducers
Author(s) -
Orekhov Philipp,
Bothe Arne,
Steinhoff HeinzJürgen,
Shaitan Konstantin V.,
Raunser Stefan,
Fotiadis Dimitrios,
Schlesinger Ramona,
Klare Johann P.,
Engelhard Martin
Publication year - 2017
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/php.12763
Subject(s) - rhodopsin , sensory system , biophysics , chemistry , g protein coupled receptor , receptor , crystallography , biology , biochemistry , neuroscience , retinal
Abstract Archaeal photoreceptors consist of sensory rhodopsins in complex with their cognate transducers. After light excitation, a two‐component signaling chain is activated, which is homologous to the chemotactic signaling cascades in enterobacteria. The latter system has been studied in detail. From structural and functional studies, a picture emerges which includes stable signaling complexes, which assemble to receptor arrays displaying hexagonal structural elements. At this higher order structural level, signal amplification and sensory adaptation occur. Here, we describe electron microscopy data, which show that also the archaeal phototaxis receptors sensory rhodopsin I and II in complex with their cognate transducers can form hexagonal lattices even in the presence of a detergent. This result could be confirmed by molecular dynamics calculations, which revealed similar structural elements. Calculations of the global modes of motion displayed one mode, which resembles the “U”‐”V” transition of the Np SRII : Np Htr II complex, which was previously argued to represent a functionally relevant global conformational change accompanying the activation process [Ishchenko et al. (2013) J. Photochem. Photobiol. B 123, 55‐58]. A model of cooperativity at the transmembrane level is discussed.