Analysis of light-induced conformational changes of Natronomonas pharaonis sensory rhodopsin II by time resolved electron paramagnetic resonance spectroscopy.
The nature and kinetics of the conformational changes leading to the activated state of NpSRII/NpHtrII157 were investigated by time-resolved electron paramagnetic resonance (TR-EPR) spectroscopy in combination with site-directed spin labeling (SDSL) on a series of spin labeled mutants of NpSRII. A structural rearrangement of the cytoplasmic moiety of NpSRII upon light activation was detected (helices B, C, F and G). The increase in distance between helices C and F in the M-trapped state of the complex observed in one double mutant is in line with the notion that an outward movement of helix F occurs upon receptor activation. The data obtained from the NpSRII/NpHtrII157 complex reconstituted in purple membrane lipids are compared with those obtained from the X-ray structure of the late M-state of the complex which shows some discrepancies. The results are discussed in the context also of other biophysical and EPR experimental evidences.
Bordignon
Enrica
E
Fachbereich Physik, Universität Osnabrück, Osnabrück, Germany.
Klare
Johann P
JP
Holterhues
Julia
J
Martell
Swetlana
S
Krasnaberski
Aliaksei
A
Engelhard
Martin
M
Steinhoff
Heinz-Jürgen
HJ
D019843:Archaeal Proteins / Q000737:chemistry / Q000235:genetics; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D006216:Halobacteriaceae / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects; D025602:Halorhodopsins / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects; D008027:Light; D008958:Models, Molecular; D046912:Multiprotein Complexes; D016297:Mutagenesis, Site-Directed; D010777:Photochemistry; D011487:Protein Conformation / Q000528:radiation effects; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000528:radiation effects; D025603:Sensory Rhodopsins / Q000737:chemistry* / Q000235:genetics / Q000528:radiation effects
D019843:Archaeal Proteins; D025602:Halorhodopsins; C434451:HtrII protein, Natronobacterium pharaonis; D046912:Multiprotein Complexes; D011994:Recombinant Proteins; D025603:Sensory Rhodopsins; C061508:sensory rhodopsin II protein, archaeal