title: Protein-protein interaction changes in an archaeal light-signal transduction.
abstract: Negative phototaxis in Natronomonas pharaonis is initiated by transient interaction changes between photoreceptor and transducer. pharaonis phoborhodopsin (ppR; also called pharaonis sensory rhodopsin II, psR-II) and the cognate transducer protein, pHtrII, form a tight 2 : 2 complex in the unphotolyzed state, and the interaction is somehow altered during the photocycle of ppR. We have studied the signal transduction mechanism in the ppR/pHtrII system by means of low-temperature Fourier-transform infrared (FTIR) spectroscopy. In the paper, spectral comparison in the absence and presence of pHtrII provided fruitful information in atomic details, where vibrational bands were identified by the use of isotope-labeling and site-directed mutagenesis. From these studies, we established the two pathways of light-signal conversion from the receptor to the transducer; (i) from Lys205 (retinal) of ppR to Asn74 of pHtrII through Thr204 and Tyr199, and (ii) from Lys205 of ppR to the cytoplasmic loop region of pHtrII that links Gly83.
authors.affiliation: Department of Frontier Materials, Nagoya Institute of Technology, Showa-ku, Nagoya 466-8555, Japan. kandori@nitech.ac.jp
authors.forename: Hideki
authors.initials: H
authors.lastname: Kandori
authors.forename: Yuki
authors.initials: Y
authors.lastname: Sudo
authors.forename: Yuji
authors.initials: Y
authors.lastname: Furutani
mesh_terms: D019843:Archaeal Proteins / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D055537:Light Signal Transduction; D019633:Natronobacterium / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D025603:Sensory Rhodopsins / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013912:Threonine / Q000378:metabolism
chemical_list: D019843:Archaeal Proteins; D025603:Sensory Rhodopsins; D013912:Threonine