Biophysical Chemistry on photobrhodopsin, a sensor for a negative taxis of Halobacterium

法老钠杆菌phoborhodopsin （ppR）是法老钠杆菌负趋光性的传感器。光照激发ppR， ppR松弛到原基态。这种线性和循环的光化学称为光循环。在膜内，ppR与传感器蛋白pHtrII形成复合体，该复合体将光信号传递到细胞质。(1)通过高压实验和SVD分析发现了一种新的光中间体。(2)在光循环过程中释放质子的氨基酸残基的分配。(3)络合物的化学计量测定(4)络合物形成所需氨基酸残基的分配。(5)配合物的KD值在光循环过程中发生100倍的变化。(6)螺旋-螺旋相互作用对调色的重要性。

pharaonis phoborhodopsin (ppR) is a sensor for negative phototaxis of Natronobacterium pharaonis. Illumination excites ppR, which relaxed to the original ground state of ppR. This linear and cyclic photochemistry is called photocycle. Within membranes, ppR forms a complex with a transducer protein, pHtrII, and this complex transmits photo-signals to cytoplasm. This research clarified as follows(1) Discovery of a new photo-intermediate after high-pressure experiments and SVD analysis.(2) Assignment of an amino acid residue from which proton is released during photocycling.(3) Determination of the stoichiometry of the complex(4) Assignment of essential amino acid residues for the formation of the complex.(5) One hundred-fold alternation of KD values of the complex during photocycling.(6) Importance of helix-helix interaction for the color tuning.