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首页> 外文期刊>Biochemistry >Conservation and Diversity in the Primary Forward Photodynamics of Red/Green Cyanobacteriochromes
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Conservation and Diversity in the Primary Forward Photodynamics of Red/Green Cyanobacteriochromes

机译：红色和绿色蓝细菌色素的初级正向光动力学中的保守性和多样性

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摘要

Phytochromes are red/far-red photosensory proteins that detect the ratio of red to far-red light. Crucial to light regulation of plant developmental biology, phytochromes are also found in fungi, bacteria, and eukaryotic algae. In addition to phytochromes, cyanobacteria also can contain distantly related cyanobacteriochromes (CBCRs) that, like phytochromes, utilize the photoisomerization of a linear tetrapyrrole (bilin) chromophore to convert between two photostates with distinct spectral properties. CBCRs exhibit a wide range of photostates spanning the visible and even near-ultraviolet spectrum. In both phytochromes and CBCRs, biosynthesis initially yields a holoprotein with bilin in the 15Z configuration, and the 15E photoproduct can often revert to the 15Z photostate in the absence of light (dark reversion). One CBCR subfamily, red/green CBCRs, typically exhibits red-absorbing dark states and green-absorbing photoproducts. Dark reversion is extremely variable in red/green CBCRs with known examples ranging from seconds to days. One red/green CBCR, NpR6012g4 from Nostoc punctiforme, is also known to exhibit forward photoconversion that has an unusually high quantum yield at similar to 40% compared to 1020% for phytochromes and CBCRs from other subfamilies. In the current study, we use time-resolved pump-probe absorption spectroscopy with broadband detection and multicomponent global analysis to characterize forward photoconversion of seven additional red/green CBCRs from N. punctiforme on an ultrafast time scale. Our results reveal that red/green CBCRs exhibit a conserved pathway for primary forward photoconversion but that considerable diversity exists in their excited-state lifetimes, photochemical quantum yields, and primary photoproduct stabilities.
机译：植物色素是红色/远红色的光敏蛋白，可检测红色与远红色的比率。对植物发育生物学的光调节至关重要，在真菌，细菌和真核藻类中也发现了植物色素。除植物色素外，蓝细菌还可以包含远缘相关的蓝细菌色素（CBCR），与植物色素一样，它们利用线性四吡咯（bilin）生色团的光异构化在两个具有不同光谱特性的光态之间转换。 CBCR具有广泛的光态，涵盖可见光甚至近紫外光谱。在植物色素和CBCR中，生物合成最初都会产生带有BiZ的15Z构型的全蛋白，并且15E的光产物在没有光照的情况下通常可以还原为15Z的光态（暗还原）。一个CBCR亚家族，红色/绿色CBCR，通常表现出吸收红光的暗态和吸收绿色的光产物。在红色/绿色CBCR中，暗色还原的变化非常大，已知示例的范围从几秒到几天。还已知一种红色/绿色的CBCR，来自点状的Nostoc的NpR6012g4，具有正向光转换，该光具有异常高的量子产率，与其他亚科的植物色素和CBCR的1020％相比，其量子产率接近40％。在当前的研究中，我们将时间分辨泵浦探针吸收光谱技术与宽带检测和多组分全局分析结合使用，以超快的时间尺度表征点状猪笼草另外七个红色/绿色CBCR的正向光转换。我们的结果表明，红色/绿色CBCRs表现出保守的初级正向光转化途径，但在其激发态寿命，光化学量子产率和初级光产物稳定性方面存在相当大的多样性。

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