Molecular Mechanism of tR - New Photosensory Receptor in Halobacterium Halobium

盐生盐杆菌中除含有细菌视紫红质和盐视紫红质外，还含有第三类视紫红质色素（tR）。最近的研究表明，感觉视紫红质（sR;由tR重新命名）负责红光的正趋光性和蓝光的负趋光性。在本项目中表征的感觉视紫红质（SR 590）具有长寿命的中间吸收370 nm（SR 370）。用化学萃取法提取感觉性视紫红质中的视黄醛，经HPLC测定其异构体组成，发现SR 590和SR 370中的视黄醛异构体分别为全反式和13-顺式，用激光光解法研究了感觉性视紫红质的光循环。SR 570的主要光产物是SR 680，吸收680 nm。Bogomolni等人显示SR 680转化为SR 370。然而，我们在SR 680和SR 370之间发现了新的中间体SRL。正如我们已经表明的，SR 370的量子产率随着温度的降低而降低。为了解释这一现象，我们研究了温度效应， ...更多信息 对SR 680量子产率进行了测试。与SR 370相比，SR 680的量子产率与温度无关。这些结果表明从SR 680到SR 590存在旁路。SR 370是负趋光性的光感受器，预期具有其自身的光循环。研究了SR 370在红光连续照射下的光循环。闪光后1 ms测得的差谱中的最大值为-520 nm。在高压下用闪光光解法研究了离子与感觉视紫红质之间的相互作用。该方法使我们能够获得活化摩尔体积变化<DELTA>&lt;V^（++）&gt;。虽然盐视紫红质在不同的卤化钠溶液中产生不同的体积变化，但感觉性视紫红质的体积变化与单价离子的种类无关。然而，二价阳离子（&lt;Mg^（++）&gt;，&lt;Ca^（++）&gt;）影响摩尔体积变化，为了表征感觉性视紫红质，必须将其溶解后分离。该项目正在调查中。少

In addition to bacteriorhodopsin and halorhodopsin, third-rhodopsin like pigment (tR) was found in Halobacterium halobium. Recent Studies show sensory rhodopsin (sR; renamed from tR) is responsible for positive phototaxis by red light and for negative phototaxis by blue light. In this project characterization of sensory rhodopsin (SR590) has a long live intermediate absorbing 370 nm (SR370). Isomeric composition of retinal in sensory rhodopsin was determined by HPLC after chemical extraction.The isomeric form of retinal in SR590 and SR370 was found to be all-trans retinal and 13-cis retinal, respectively.Photocycle of sensory rhodopsin was studied using laser flash photolysis. Primary photoproduct of SR570 is SR680, absorbing 680 nm. Bogomolni et al show SR680 converts to SR370. However, we found new intermediate SRL between SR680 and SR370. As we already showed, quantum yield of SR370 decreased in decreasing temperature. In order to explain this phenomena, we studied temperature effec … More t on quantum yield of SR680. In contrast with SR370, quantum yield of SR680 is independent of temperature. These results suggest there is bypass from SR680 to SR590. SR370 is photoreceptor for negative phototaxis and is expected to have its own photocycle. After accumulate of SR370 with continuous illumination of red light, photocycle of SR370 was studied with blue pulse light. The maximum in the difference spectrum measured 1 ms after the flash is - 520 nm.Interaction between ions and sensory rhodopsin was studied by flash photolysis under high pressures. This method enable us to obtain activated molar volume changed <DELTA> <V^(++)> . Though halorhodopsin gave different volume changes with different sodium halide, volume changes of sensory rhodopsin were independent of sort of monovalent ion. However, Divalent cation ( <Mg^(++)> , <Ca^(++)> ) affect the molar volume changes.In order to characterize sensory rhodopsin, this pigment have to be isolated after solublized. This project is under investigation. Less