Department of Plant Genetics, Weizmann Institute of Science, 76100 Rehovot, Israel.
EMBO J. 1987 Nov;6(11):3233-7. doi: 10.1002/j.1460-2075.1987.tb02640.x.
The chloroplast genes coding for the 16S ribosomal RNA from several spectinomycin-resistant Nicotiana mutants were analyzed. Two classes of mutants were identified. In one class, a G to A base transition is found at position 1140 of the tobacco-chloroplast 16S rRNA gene, which eliminates an AatII restriction endonuclease site. This base transition is proximal to a mutation previously described for spectinomycin resistance in Escherichia coli. In the other class, a novel G to A transition is found at position 1012 of the 16S rRNA gene. Although the mutations in the two classes are 128 nucleotides apart, the secondary structure model for 16S rRNA suggests that the two mutated nucleotides are in spatial proximity on opposite sides of a conserved stem structure in the 3' region of the molecule. Phylogenetic evidence is presented linking this conserved stem with spectinomycin resistance in chloroplasts. Perturbation of the stem is proposed to be the molecular-genetic basis for rRNA-dependent spectinomycin resistance.
我们分析了几种壮观霉素抗性烟草原生质体基因编码 16S 核糖体 RNA 的基因。鉴定出两类突变体。在一类突变体中，在烟草质体 16S rRNA 基因的 1140 位发现了 G 到 A 的碱基转换，从而消除了 AatII 限制内切酶位点。该碱基转换与先前描述的大肠杆菌中壮观霉素抗性的突变非常接近。在另一类突变体中，在 16S rRNA 的 1012 位发现了一个新的 G 到 A 的转换。尽管两类突变之间相差 128 个核苷酸，但 16S rRNA 的二级结构模型表明，这两个突变核苷酸在分子 3' 区域保守茎结构的相反侧处于空间接近的位置。提出了与叶绿体中壮观霉素抗性相关的系统发育证据。建议茎的扰动是 rRNA 依赖性壮观霉素抗性的分子遗传基础。
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