IDENTIFICATION OF A 3RD-RHODOPSIN-LIKE PIGMENT IN PHOTOTACTIC HALOBACTERIUM-HALOBIUM
IDENTIFICATION OF A 3RD-RHODOPSIN-LIKE PIGMENT IN PHOTOTACTIC HALOBACTERIUM-HALOBIUM
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DOI：
10.1073/pnas.79.20.6250
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发表时间：
1982-01-01
期刊：
影响因子：
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通讯作者：
SPUDICH, JL
中科院分区：
文献类型：
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作者：
BOGOMOLNI, RA;SPUDICH, JL
变异的H.所有先前报道的视紫红质样色素缺陷的盐生菌菌株显示出与野生型菌株相当的趋光性反应。光谱分析揭示了在细胞及其膜组分中存在第三种含视黄醇的色素。它经历半衰期为λ的光反应循环。1 s在室温和生理光强度的光稳定状态的色素由2种，一个吸收在580- 590-nm区域和其他在373 nm，这两个都是光活性的。长波长物质的照射产生373 nm的中间体，其在光激发下重新转换为长波长形式。因此，可见光谱的长波长和短波长区域中的相对光强度的变化引起光稳态的相反偏移。这种色素的光谱敏感性与这种生物体的颜色辨别趋光性敏感性相关，并强烈表明它是感觉光感受器。
Mutant H. halobium strains deficient in all previously reported rhodopsin-like pigments show phototaxis responses comparable to those of wild-type strains. Spectroscopic analysis reveals the presence of a 3rd retinal-containing pigment in the cells and their membrane fractions. It undergoes a photoreaction cycle with a half-time of .apprx. 1 s at room temperature and at physiological light intensities the photostationary state of the pigment consists of 2 species, one absorbing in the 580-to 590-nm region and the other at 373 nm, both of which are photoactive. Illumination of the long-wavelength species generates the 373-nm intermediate, which upon photoexcitation reconverts to the long-wavelength form. Therefore, changes in the relative light intensities in the long- and short-wavelength regions of the visible spectrum cause opposing shifts in the photostationary state. The spectral sensitivity of this pigment correlates with the color-discriminating phototaxis sensitivities of this organism and strongly suggests that it is the sensory photoreceptor.