Bruce D, Brimble S, Bryant D A
Department of Biological Sciences, Brock University, St. Catharines, Canada.
Biochim Biophys Acta. 1989 Apr 17;974(1):66-73. doi: 10.1016/s0005-2728(89)80166-5.
State transitions were investigated in the cyanobacterium Synechococcus sp. PCC 7002 in both wild-type cells and mutant cells lacking phycobilisomes. Preillumination in the presence of DCMU induced State 1 and dark-adaptation induced State 2 in both wild-type and mutant cells as determined by 77 K fluorescence emission spectroscopy. Light-induced transitions were observed in the wild-type after preferential excitation of phycocyanin (State 2) or preferential excitation of Chl a (State 1). Light-induced transitions were also observed in the phycobilisome-less mutant after preferential excitation of short-wavelength Chl a (State 2) or carotenoids and long-wavelength Chl a (State 1). We conclude that the mechanism of the light-state transition in cyanobacteria does not require the presence of the phycobilisome. Our results contradict proposed models for the state transition, which require phosphorylation of, and an active role for, the phycobilisome.
在野生型细胞和缺乏藻胆体的突变体细胞中，对蓝藻聚球藻属PCC 7002的状态转变进行了研究。通过77K荧光发射光谱法测定，在存在二氯苯基二甲基脲（DCMU）的情况下进行预照明诱导野生型和突变体细胞进入状态1，黑暗适应诱导进入状态2。在野生型中，在优先激发藻蓝蛋白（状态2）或优先激发叶绿素a（状态1）后观察到光诱导转变。在缺乏藻胆体的突变体中，在优先激发短波长叶绿素a（状态2）或类胡萝卜素和长波长叶绿素a（状态1）后也观察到光诱导转变。我们得出结论，蓝藻中光状态转变的机制不需要藻胆体的存在。我们的结果与提出的状态转变模型相矛盾，后者要求藻胆体进行磷酸化并发挥积极作用。
