Isolation and Characterization of the Blue-Green Photoreceptor of H Halobium

嗜光古细菌H.halobium含有光驱动的质子泵、氯化泵、细菌视紫红质和卤视紫质。研究发现，缺乏这两种视紫红质的突变体仍然是趋光性的，光信号受体实际上是两种视网膜色素，即感觉性视紫红素I和II。它们构成了一个原始的颜色识别系统，其基础是化学上与动物的光和色觉色素相似的色素。该方案的目的是分离、纯化和鉴定最近发现的sr-II受体，并将其功能和特性与高等生物的感官色素进行比较。这些结果应该会对设计用于能量和感觉转导的膜蛋白及其进化发展的原理产生新的见解。

The phototactic archaeobacterium H. halobium contains the light-driven proton and chloride pumps bacteriorhodopsin and halorhodopsin. It has been found that mutants deficient in both rhodopsins are still phototactic, and that the light signal receptors are actually two retinal pigments, the sensory rhodopsins (sR's) I and II. They constitute a primitive color discrimination system based on pigments chemically similar to the light and color sensing pigments of animals. The goal of this proposal is to isolate, purify and characterize the recently identified sR-II receptor, and compare its function and properties with those of the sensory pigments of higher organisms. The results should yield new insights on the principles which underlie the design of membrane proteins for energy and sensory transduction and their evolutionary development.