High-field EPR and site-directed spin labeling reveal a periodical polarity profile: The sequence 88 to 94 of the phototransducer NpHtrII in complex with sensory rhodopsin, NpSRII

Autor(en): Brutlach, H.
Bordignon, E.
Urban, L.
Klare, J. P.
Reyher, H. -J.
Engelhard, M.
Steinhoff, H. -J.
Stichwörter: 95-GHZ; CHAINS; CONFORMATIONAL-CHANGES; Physics; Physics, Atomic, Molecular & Chemical; RESONANCE; SPECTROMETER; Spectroscopy
Erscheinungsdatum: 2006
Herausgeber: SPRINGER WIEN
Volumen: 30
Ausgabe: 3-4
Startseite: 359
Seitenende: 372
Taking advantage of the improved spectral resolution of high-field electron paramagnetic resonance (EPR) at 95 GHz/3.4 T as compared to conventional X-band EPR (9.5 GHz/0.34 T), detailed information on the polarity profile in a protein-protein interface is obtained. Nitroxide spin label side chains are introduced at positions 88 to 94 in the AS-1 sequence of the membrane adjacent HAMP domain of the transducer protein, NpHtrII, which is reconstituted in complex with sensory rhodopsin, NpSRII from Natronobacterium pharaonis. Position-dependent variations of the values of the nitroxide magnetic tenser components g(xx) and A(zz) suggest that the spin label side chains at positions 88 to 93 of AS-1 are located between a hydrophobic and a hydrophilic microenvironment. The observed periodicity of the polarity properties of the respective spin label microenvironment agrees with an a-helical secondary structure of this part of AS-1 and validates a recently published molecular model which locates residues 88 and 91 in the interface between helices F and G of NpSRII and AS-1 of NpHtrII close to the cytoplasmic lipid-water interface.
ISSN: 09379347
DOI: 10.1007/BF03166206

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