Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris
Characterization of red-shifted phycobilisomes isolated from the chlorophyll f-containing cyanobacterium Halomicronema hongdechloris
复制标题
DOI：
10.1016/j.bbabio.2015.10.009
复制
发表时间：
2016-01-01
影响因子：
4.3
通讯作者：
Chen, Min
中科院分区：
文献类型：
--
作者：
Li, Yaqiong;Lin, Yuankui;Chen, Min
藻胆体是蓝藻和一些藻类中主要的光收集蛋白复合物。人们普遍认为这些复合物只吸收绿光和橙光，与叶绿素吸收互补。在这里，我们提出了一个新的藻胆异构体衍生的复合物，它仅由异藻蓝蛋白核心亚基组成，具有653和712 nm的红移吸收峰。这些红移藻胆蛋白复合物是从含叶绿素f的蓝藻（Halomicronema hongdechloris）中分离出来的，在单色730 nm波长（远红光）光下生长。单粒子分析得到的三维模型显示了一个120-145埃的双盘组合，两个α / β异藻蓝蛋白三聚体分别位于两个分离的圆盘上。它们明显小于由异藻蓝蛋白亚基和核膜连接蛋白形成的典型藻胆体，这与在远红光下生长的细胞中观察到的类囊体膜之间的距离减小非常吻合。在这两种光条件下生长的解离和变性藻胆蛋白复合物的光谱分析表明，它们完全使用了相同的十亿蛋白发色团——藻蓝胆素。我们的研究结果表明，红移藻胆体是协助有效的远红光收集所必需的。他们的发现为极端条件下光合作用的光捕获分子机制提供了新的见解，以及在不同光照条件下灵活适应色彩的策略。(C) 2015 Elsevier B.V.版权所有
Phycobilisomes are the main light-harvesting protein complexes in cyanobacteria and some algae. It is commonly accepted that these complexes only absorb green and orange light, complementing chlorophyll absorbance. Here, we present a new phycobilisome derived complex that consists only of allophycocyanin core subunits, having red-shifted absorption peaks of 653 and 712 nm. These red-shifted phycobiliprotein complexes were isolated from the chlorophyll f-containing cyanobacterium, Halomicronema hongdechloris, grown under monochromatic 730 nm-wavelength (far-red) light. The 3D model obtained from single particle analysis reveals a double disk assembly of 120-145 angstrom with two alpha/beta allophycocyanin trimers fitting into the two separated disks. They are significantly smaller than typical phycobilisomes formed from allophycocyanin subunits and core-membrane linker proteins, which fit well with a reduced distance between thylakoid membranes observed from cells grown under far-red light. Spectral analysis of the dissociated and denatured phycobiliprotein complexes grown under both these light conditions shows that the same bilin chromophore, phycocyanobilin, is exclusively used. Our findings show that red-shifted phycobilisomes are required for assisting efficient far-red light harvesting. Their discovery provides new insights into the molecular mechanisms of light harvesting under extreme conditions for photosynthesis, as well as the strategies involved in flexible chromatic acclimation to diverse light conditions. (C) 2015 Elsevier B.V. All rights reserved.