Hirose Yuu, Misawa Naomi, Yonekawa Chinatsu, Nagao Nobuyoshi, Watanabe Mai, Ikeuchi Masahiko, Eki Toshihiko
Department of Environmental and Life Sciences, Toyohashi University of Technology, 1-1 Hibarigaoka, Tempaku, Toyohashi, Aichi 441-8580, Japan.
Department of Life Sciences (Biology), The University of Tokyo, 3-8-1 Komaba, Meguro, Tokyo 153-8902, Japan.
DNA Res. 2017 Aug 1;24(4):387-396. doi: 10.1093/dnares/dsx011.
Certain cyanobacteria can adjust the wavelengths of light they absorb by remodeling their photosynthetic antenna complex phycobilisome via a process called chromatic acclimation (CA). Although several types of CA have been reported, the diversity of the molecular mechanisms of CA among the cyanobacteria phylum is not fully understood. Here, we characterized the molecular process of CA of Geminocystis sp. strains National Institute of Environmental Studies (NIES)-3708 and NIES-3709. Absorption and fluorescence spectroscopy revealed that both strains dramatically alter their phycoerythrin content in response to green and red light. Whole-genome comparison revealed that the two strains share the typical phycobilisome structure consisting of a central core and peripheral rods, but they differ in the number of rod linkers of phycoerythrin and thus have differing capacity for phycoerythrin accumulation. RNA sequencing analysis suggested that the length of phycoerythrin rods in each phycobilisome is strictly regulated by the green light and red light-sensing CcaS/R system, whereas the total number of phycobilisomes is governed by the excitation-balancing system between phycobilisomes and photosystems. We reclassify the conventional CA types based on the genome information and designate CA of the two strains as genuine type 2, where components of phycoerythrin, but not rod-membrane linker of phycocyanin, are regulated by the CcaS/R system.
某些蓝细菌可以通过一种称为色适应（CA）的过程重塑其光合天线复合体藻胆体，从而调整它们吸收的光的波长。尽管已经报道了几种类型的CA，但蓝细菌门中CA分子机制的多样性尚未完全了解。在这里，我们对双囊藻属菌株国立环境研究所（NIES）-3708和NIES-3709的CA分子过程进行了表征。吸收光谱和荧光光谱显示，这两种菌株都能响应绿光和红光显著改变其藻红蛋白含量。全基因组比较显示，这两种菌株具有由中央核心和外周杆组成的典型藻胆体结构，但它们在藻红蛋白杆连接体的数量上有所不同，因此藻红蛋白积累能力也不同。RNA测序分析表明，每个藻胆体中藻红蛋白杆的长度受绿光和红光感应CcaS/R系统严格调控，而藻胆体的总数则由藻胆体和光系统之间的激发平衡系统控制。我们根据基因组信息对传统的CA类型进行了重新分类，并将这两种菌株的CA指定为真正的2型，其中藻红蛋白的成分，而不是藻蓝蛋白的杆-膜连接体，受CcaS/R系统调控。
