Department of Molecular Genetics and Cell Biology. The University of Chicago, Chicago, IL 60637, USA.
EMBO J. 1989 Apr;8(4):1237-45. doi: 10.1002/j.1460-2075.1989.tb03497.x.
The transformable cyanobacterium, Synechococcus sp. PCC7942, was used to study the genetics of resistance to the herbicide diuron. In wild-type cells, diuron binds to one of the core proteins, called D1, of photosystem II reaction centres. This binding prevents the transfer of electrons from Q(A), the primary quinone acceptor, to Q(B), which is necessary to create the charge separation that drives ATP synthesis. A single amino acid substitution in the D1 protein reduces diuron binding and confers herbicide resistance to reaction centres containing the substituted D1 protein. In Synechococcus 7942, the D1 protein is encoded by three functional genes called psbAI, psbAII and psbAIII. By selectively altering one member at a time of the three-member psbA gene family, we have demonstrated that diuron-resistant alleles are dominant to diuron-sensitive alleles. The relative abundance of the different psbA gene transcripts is correlated with the fraction of diuron-resistant reaction centres and with the degree of diuron resistance. Growth in sublethal diuron selectively increases the steady-state levels of transcripts of genes (psbA and psbD) encoding the core proteins of photosystem II. We have also found that turnover of the D1 protein can be uncoupled from electron transport through photosystem II.
可转化蓝藻，集胞藻 PCC7942，被用于研究对除草剂敌草隆的抗性的遗传学。在野生型细胞中，敌草隆与光合作用 II 反应中心的核心蛋白之一 D1 结合。这种结合阻止电子从 Q(A)，主要的醌受体，转移到 Q(B)，这是驱动 ATP 合成所必需的。D1 蛋白中的单个氨基酸取代会降低敌草隆的结合，并赋予含有取代 D1 蛋白的反应中心对除草剂的抗性。在集胞藻 7942 中，D1 蛋白由三个功能基因 psbAI、psbAII 和 psbAIII 编码。通过选择性地一次改变三成员 psbA 基因家族中的一个成员，我们已经证明敌草隆抗性等位基因是对敌草隆敏感等位基因的显性。不同 psbA 基因转录本的相对丰度与敌草隆抗性反应中心的分数和敌草隆抗性的程度相关。亚致死剂量的敌草隆选择性地增加了编码光合作用 II 核心蛋白的基因(psbA 和 psbD)的转录本的稳态水平。我们还发现，D1 蛋白的周转可以与通过光合作用 II 的电子传递解偶联。
