Sequences directing C to U editing of the plastid psbL mRNA are located within a 22 nucleotide segment spanning the editing site
Sequences directing C to U editing of the plastid psbL mRNA are located within a 22 nucleotide segment spanning the editing site
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DOI：
10.1002/j.1460-2075.1996.tb00982.x
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发表时间：
1996-11-01
期刊：
影响因子：
11.4
通讯作者：
Maliga, P
中科院分区：
文献类型：
--
作者：
Chaudhuri, S;Maliga, P
在质体中，将ACG密码子编辑为AUG密码子产生烟草中psbL和ndhD转录物的翻译起始密码子。为了鉴定psbL编辑所需的RNA片段，构建了含有psbL缺失衍生物的嵌合卡那霉素抗性基因，并在转基因植物中进行体内编辑测试。我们在此报道，22个核苷酸的片段足以指导有效的psbL编辑，包括编辑位点上游的16个核苷酸和编辑位点下游的5个核苷酸。编辑位点上游的A核苷酸突变为C完全消除了编辑，而下游的G突变为C仅降低了编辑效率。在22个核苷酸的编辑靶序列中，发现16个上游核苷酸与内源性psbL转录物竞争可耗尽的反式因子。为了测试起始密码子的编辑是否涉及共同的反式因子，在烟草质体中表达含有ndhD编辑位点的嵌合基因。然而，ndhD反式因子与psbL编辑所需的不同。psbL和ndhD编辑位点的不同顺式序列和反式因子要求表明质体起始密码子编辑的个体识别机制。
In plastids, editing of an ACG codon to an AUG codon creates the translation initiation codon for the psbL and ndhD transcripts in tobacco, To identify the RNA segment required for psbL editing, chimeric kanamycin resistance genes were constructed containing psbL deletion derivatives, and tested in vivo for editing in transgenic plants, We report here that a 22 nucleotide segment is sufficient to direct efficient psbL editing, including 16 nucleotides upstream and five nucleotides downstream of the editing site, Mutation of the A nucleotide to a C upstream of the editing site completely abolished editing, while mutation of the downstream G to a C only reduced the editing efficiency, Out of the 22 nucleotide editing target sequence, the 16 upstream nucleotides were found to compete with the endogenous psbL transcript for a depletable trans-factor. To test whether editing of initiation codons involves a common trans-factor, a chimeric gene containing the ndhD editing site was expressed in tobacco plastids, As for psbL, editing of the ndhD site requires a depletable trans-factor. However, the ndhD trans-factor is distinct from that required for psbL editing, Distinct cis-sequences and trans-factor requirements for the psbL and ndhD editing sites indicate an individual recognition mechanism for the editing of plastid initiation codons.