Itoh Shigeru, Ohno Tomoki, Noji Tomoyasu, Yamakawa Hisanori, Komatsu Hirohisa, Wada Katsuhiro, Kobayashi Masami, Miyashita Hideaki
Center for Gene Research, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8602, Japan
Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan.
Plant Cell Physiol. 2015 Oct;56(10):2024-34. doi: 10.1093/pcp/pcv122. Epub 2015 Aug 28.
Cells of a unicellular cyanobacterium strain KC1, which were collected from Japanese fresh water Lake Biwa, formed chlorophyll (Chl) f at 6.7%, Chl a' at 2.0% and pheophytin a at 0.96% with respect to Chl a after growth under 740 nm light. The far-red-acclimated cells (Fr cells) formed extra absorption bands of Chl f at 715 nm in addition to the major Chl a band. Fluorescence lifetimes were measured. The 405-nm laser flash, which excites mainly Chl a in photosystem I (PSI), induced a fast energy transfer to multiple fluorescence bands at 720-760 and 805 nm of Chl f at 77 K in Fr cells with almost no PSI-red-Chl a band. The 630-nm laser flash, which mainly excited photosystem II (PSII) through phycocyanin, revealed fast energy transfer to another set of Chl f bands at 720-770 and 810 nm as well as to the 694-nm Chl a fluorescence band. The 694-nm band did not transfer excitation energy to Chl f. Therefore, Chl a in PSI, and phycocyanin in PSII of Fr cells transferred excitation energy to different sets of Chl f molecules. Multiple Chl f forms, thus, seem to work as the far-red antenna both in PSI and PSII. A variety of cyanobacterial species, phylogenically distant from each other, seems to use a Chl f antenna in far-red environments, such as under dense biomats, in colonies, or under far-red LED light.
从日本淡水琵琶湖采集的单细胞蓝藻菌株KC1的细胞，在740nm光照下生长后，相对于叶绿素a，形成了6.7%的叶绿素（Chl）f、2.0%的叶绿素a'和0.96%的脱镁叶绿素a。远红光适应细胞（Fr细胞）除了主要的叶绿素a带外，还在715nm处形成了叶绿素f的额外吸收带。测量了荧光寿命。405nm激光闪光主要激发光系统I（PSI）中的叶绿素a，在77K下诱导Fr细胞中叶绿素f的720 - 760和805nm处的多个荧光带发生快速能量转移，几乎没有PSI - 红色 - 叶绿素a带。630nm激光闪光主要通过藻蓝蛋白激发光系统II（PSII），显示出快速能量转移到720 - 770和810nm处的另一组叶绿素f带以及694nm的叶绿素a荧光带。694nm带没有将激发能量转移到叶绿素f。因此，Fr细胞中PSI的叶绿素a和PSII的藻蓝蛋白将激发能量转移到不同组的叶绿素f分子上。因此，多种叶绿素f形式似乎在PSI和PSII中都作为远红光天线起作用。各种在系统发育上彼此距离较远的蓝藻物种，似乎在远红光环境中，如在密集的生物膜下、菌落中或远红光LED灯下，使用叶绿素f天线。
