Department of Molecular and Cell Biology, University of California, Davis, One Shields Avenue, Davis, CA 95616, USA.
Chemphyschem. 2010 Apr 26;11(6):1172-80. doi: 10.1002/cphc.200900894.
Photosensory proteins enable living things to detect the quantity and quality of the light environment and to transduce that physical signal into biochemical outputs which entrain their metabolism with the ambient light environment. Phytochromes, which photoconvert between red-absorbing P(r) and far-red-absorbing P(fr) states, are the most extensively studied of these interesting proteins. Critical regulators of a number of key adaptive processes in higher plants, including photomorphogenesis and shade avoidance, phytochromes are widespread in photosynthetic and nonphotosynthetic bacteria, and even in fungi. Cyanobacterial genomes also possess a plethora of more distant relatives of phytochromes known as cyanobacteriochromes (CBCRs). Biochemical characterization of representative CBCRs has demonstrated that this class of photosensors exhibits a broad range of wavelength sensitivities, spanning the entire visible spectrum. Distinct protein-bilin interactions are responsible for this astonishing array of wavelength sensitivities. Despite this spectral diversity, all members of the extended family of phytochrome photosensors appear to share a common photochemical mechanism for light sensing: photoisomerization of the 15/16 double bond of the bilin chromophore.
感光蛋白使生物能够感知光环境的数量和质量，并将物理信号转化为生物化学输出，使它们的新陈代谢与周围的光环境同步。光敏色素是研究最广泛的这类有趣蛋白之一，它在红光吸收态 P(r) 和远红光吸收态 P(fr) 之间发生光致变色。作为高等植物中许多关键适应过程的关键调节剂，包括光形态发生和避荫反应，光敏色素广泛存在于光合和非光合细菌中，甚至在真菌中也存在。蓝藻基因组还拥有大量被称为蓝藻视紫红质（CBCRs）的光敏色素远亲。对代表性 CBCRs 的生化特性的研究表明，这类光传感器具有广泛的波长敏感性，涵盖整个可见光谱。不同的蛋白-视黄醛相互作用负责这种惊人的波长敏感性。尽管存在这种光谱多样性，但类视黄醛光感受器的扩展家族的所有成员似乎都共享一个共同的光感测光化学机制：视黄醛发色团的 15/16 双键的光致异构化。
