Department of Molecular and Cell Biology, Penn State University, 16802, University Park, PA, USA.
Photosynth Res. 1988 Apr;16(1-2):83-99. doi: 10.1007/BF00039487.
Two herbicide-resistant strains of the cyanobacterium Synechococcus sp. PCC 7002 are compared to the wild-type with respect to the DNA changes which result in herbicide resstance. The mutations have previously been mapped to a region of the cyanobacterial genome which encodes oneof three copies of psbA, the gene which encodes the 32 kDa Qb-binding protein also known as D1 (Buzby et al. 1987). The DNA sequence of the wild-type gene was first determined and used as a comparison to that of the mutant alleles. A point mutation at codon 211 in the psbA1 coding locus (TTC) to TCC) results in an amino acid change from phenylalanine to serine in the D1 protein. This mutation confers resistance to atrazine and diuron at seven times and at two times the minimal inhibitory concentration (MIC) for the wild-type, respectively. A mutation at codon 211 resulting in herbicide resistance has not previously been described in the literature. A second point mutation at codon 219 in the psbA1 coding locus (GTA to ATA) results in an amino acid change from valine to isoleucine in the D1 protein. This mutation confers resistance to diuron and atrazine at ten times and at two times the MIC for the wild-type, respectively. An identical codon change conferring similar herbicide resistance patterns has previously been described in Chlamydomonas reinhardtii. The atrazine-resistance phenotype in Synechococcus sp. PCC 7002 was shown to be dominant by plasmid segregation analysis.
两种对除草剂具有抗性的鱼腥蓝细菌（Synechococcus sp. PCC 7002）品系与野生型相比，在导致除草剂抗性的 DNA 变化方面有所不同。这些突变先前已被定位到蓝藻基因组的一个区域，该区域编码 psbA 的三个拷贝之一，psbA 基因编码 32kDa Qb 结合蛋白，也称为 D1（Buzby 等人，1987）。野生型基因的 DNA 序列首先被确定，并用作与突变等位基因的比较。在 psbA1 编码基因座（TTC）中的密码子 211 处发生点突变（TTC）到 TCC）导致 D1 蛋白中的苯丙氨酸突变为丝氨酸。这种突变使 D1 蛋白对莠去津和敌草隆的抗性分别提高了 7 倍和 2 倍，MIC 为野生型的最低抑制浓度。在文献中尚未描述过导致除草剂抗性的密码子 211 突变。在 psbA1 编码基因座的密码子 219 处发生的第二个点突变（GTA 到 ATA）导致 D1 蛋白中的缬氨酸突变为异亮氨酸。这种突变使 D1 蛋白对敌草隆和莠去津的抗性分别提高了 10 倍和 2 倍，MIC 为野生型的最低抑制浓度。在先前已经描述过的莱茵衣藻（Chlamydomonas reinhardtii）中，相同的密码子变化赋予了类似的除草剂抗性模式。通过质粒分离分析表明，鱼腥蓝细菌（Synechococcus sp. PCC 7002）中的莠去津抗性表型是显性的。
