Ho Ming-Yang, Gan Fei, Shen Gaozhong, Bryant Donald A
403C Althouse Laboratory, Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
Intercollege Graduate Degree Program in Plant Biology, The Pennsylvania State University, University Park, PA, 16802, USA.
Photosynth Res. 2017 Feb;131(2):187-202. doi: 10.1007/s11120-016-0303-5. Epub 2016 Sep 13.
Phycobilisomes (PBS) are antenna complexes that harvest light for photosystem (PS) I and PS II in cyanobacteria and some algae. A process known as far-red light photoacclimation (FaRLiP) occurs when some cyanobacteria are grown in far-red light (FRL). They synthesize chlorophylls d and f and remodel PS I, PS II, and PBS using subunits paralogous to those produced in white light. The FaRLiP strain, Leptolyngbya sp. JSC-1, replaces hemidiscoidal PBS with pentacylindrical cores, which are produced when cells are grown in red or white light, with PBS with bicylindrical cores when cells are grown in FRL. This study shows that the PBS of another FaRLiP strain, Synechococcus sp. PCC 7335, are not remodeled in cells grown in FRL. Instead, cells grown in FRL produce bicylindrical cores that uniquely contain the paralogous allophycocyanin subunits encoded in the FaRLiP cluster, and these bicylindrical cores coexist with red-light-type PBS with tricylindrical cores. The bicylindrical cores have absorption maxima at 650 and 711 nm and a low-temperature fluorescence emission maximum at 730 nm. They contain ApcE2:ApcF:ApcD3:ApcD2:ApcD5:ApcB2 in the approximate ratio 2:2:4:6:12:22, and a structural model is proposed. Time course experiments showed that bicylindrical cores were detectable about 48 h after cells were transferred from RL to FRL and that synthesis of red-light-type PBS continued throughout a 21-day growth period. When considered in comparison with results for other FaRLiP cyanobacteria, the results here show that acclimation responses to FRL can differ considerably among FaRLiP cyanobacteria.
藻胆体（PBS）是一种天线复合体，可为蓝细菌和某些藻类中的光系统（PS）I和PS II捕获光能。当一些蓝细菌在远红光（FRL）下生长时，会发生一种称为远红光光适应（FaRLiP）的过程。它们合成叶绿素d和f，并使用与白光下产生的亚基同源的亚基对PS I、PS II和PBS进行重塑。FaRLiP菌株纤细席藻JSC-1，在细胞于红光或白光下生长时产生的具有五圆柱核心的半盘状PBS，会被细胞在FRL下生长时产生的具有双圆柱核心的PBS所取代。本研究表明，另一种FaRLiP菌株聚球藻PCC 7335的PBS在FRL下生长的细胞中不会发生重塑。相反，在FRL下生长的细胞产生独特地包含FaRLiP簇中编码的同源别藻蓝蛋白亚基的双圆柱核心，并且这些双圆柱核心与具有三圆柱核心的红光型PBS共存。双圆柱核心在650和711 nm处有吸收最大值，在730 nm处有低温荧光发射最大值。它们含有比例约为2:2:4:6:12:22的ApcE2:ApcF:ApcD3:ApcD2:ApcD5:ApcB2，并提出了一个结构模型。时间进程实验表明，在细胞从红光转移到FRL后约48小时可检测到双圆柱核心，并且在21天的生长期间红光型PBS的合成持续进行。与其他FaRLiP蓝细菌的结果相比，此处的结果表明，FaRLiP蓝细菌对FRL的适应反应可能有很大差异。
