College of Pharmaceutical Sciences, Matsuyama University, Japan.
Faculty of Advanced Life Science, Hokkaido University, Sapporo, Japan.
FEBS Lett. 2023 Sep;597(18):2334-2344. doi: 10.1002/1873-3468.14711. Epub 2023 Aug 9.
The cell membrane of Halobacterium salinarum contains a retinal-binding photoreceptor, sensory rhodopsin II (HsSRII), coupled with its cognate transducer (HsHtrII), allowing repellent phototaxis behavior for shorter wavelength light. Previous studies on SRII from Natronomonas pharaonis (NpSRII) pointed out the importance of the hydrogen bonding interaction between Thr204 and Tyr174 in signal transfer from SRII to HtrII. Here, we investigated the effect on phototactic function by replacing residues in HsSRII corresponding to Thr204 and Tyr174 . Whereas replacement of either residue altered the photocycle kinetics, introduction of any mutations at Ser201 and Tyr171 did not eliminate negative phototaxis function. These observations imply the possibility of the presence of an unidentified molecular mechanism for photophobic signal transduction differing from NpSRII-NpHtrII.
盐杆菌的细胞膜包含一个视黄醛结合的光感受器，感觉视紫红质 II（HsSRII），与它的伴侣转导蛋白（HsHtrII）相连，使细胞对较短波长的光产生排斥性趋光行为。以前对来自嗜盐碱杆菌（NpSRII）的 SRII 的研究指出了 Thr204 和 Tyr174 之间氢键相互作用在从 SRII 到 HtrII 的信号传递中的重要性。在这里，我们通过替换 HsSRII 中对应于 Thr204 和 Tyr174 的残基来研究对趋光功能的影响。尽管替换任一残基都会改变光循环动力学，但在 Ser201 和 Tyr171 引入任何突变都不会消除负趋光性功能。这些观察结果表明，存在一种不同于 NpSRII-NpHtrII 的、用于光致斥性信号转导的未知分子机制的可能性。
