Protein-Protein Interaction Changes in an Archaeal Light-Signal Transduction

[摘要] Negative phototaxis inNatronomonas pharaonisis initiated by transient interaction changes between photoreceptor and transducer.pharaonisphoborhodopsin (ppR; also calledpharaonissensory 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 ofppR.We have studied the signal transduction mechanism in theppR/pHtrII system by means of low-temperature Fourier-transform infrared (FTIR) spectroscopy.In the paper, spectral comparison in the absence and presence ofpHtrII 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) ofppR to Asn74 ofpHtrII through Thr204 and Tyr199, and (ii) from Lys205 ofppR to the cytoplasmic loop region ofpHtrII that links Gly83.

[学科分类] 基础医学