Yan B, Takahashi T, Johnson R, Derguini F, Nakanishi K, Spudich J L
Department of Chemistry, Columbia University, New York 10027.
Biophys J. 1990 Apr;57(4):807-14. doi: 10.1016/S0006-3495(90)82600-X.
An analogue of all-trans retinal in which all-trans/13-cis isomerization is blocked by a carbon bridge from C12 to C14 was incorporated into the apoproteins of sensory rhodopsin I (SR-I) and sensory rhodopsin II (SR-II, also called phoborhodopsin) in retinal-deficient Halobacterium halobium membranes. The "all-trans-locked" retinal analogue forms SR-I and SR-II analogue pigments with similar absorption spectra as the native pigments. Blocking isomerization prevents the formation of the long-lived intermediate of the SR-I photocycle (S373) and those of the SR-II photocycle (S-II360 and S-II530). A computerized cell tracking and motion analysis system capable of detecting 2% of native pigment activity was used for assessing motility behavior. Introduction of the locked analogue into SR-I or SR-II apoprotein in vivo did not restore phototactic responses through any of the three known photosensory systems (SR-I attractant, SR-I repellent, or SR-II repellent). We conclude that unlike the phototaxis receptor of Chlamydomonas reinhardtii, which has been reported to mediate physiological responses without specific double-bond isomerization of its retinal chromophore (Foster et al., 1989), all-trans/13-cis isomerization is essential for SR-I and SR-II phototaxis signaling.
一种全反式视黄醛类似物，其中全反式/13-顺式异构化被一个从C12到C14的碳桥阻断，该类似物被整合到视网膜缺陷型嗜盐菌膜中的感官视紫红质I（SR-I）和感官视紫红质II（SR-II，也称为避光视紫红质）的载脂蛋白中。“全反式锁定”视黄醛类似物形成SR-I和SR-II类似物色素，其吸收光谱与天然色素相似。阻断异构化可防止SR-I光循环（S373）和SR-II光循环（S-II360和S-II530）中长寿命中间体的形成。一个能够检测2%天然色素活性的计算机化细胞追踪和运动分析系统被用于评估运动行为。在体内将锁定类似物引入SR-I或SR-II载脂蛋白中，并未通过任何三种已知的光感系统（SR-I吸引剂、SR-I排斥剂或SR-II排斥剂）恢复趋光反应。我们得出结论，与莱茵衣藻的趋光性受体不同，据报道莱茵衣藻的趋光性受体在其视黄醛发色团没有特定双键异构化的情况下介导生理反应（Foster等人，1989年），全反式/13-顺式异构化对于SR-I和SR-II趋光信号传导至关重要。
