Vir-115 gene product is required to stabilize D1 translation intermediates in chloroplasts.
Vir-115 gene product is required to stabilize D1 translation intermediates in chloroplasts.
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Vir-115 基因产物需要稳定叶绿体中的 D1 翻译中间体。
DOI：
10.1007/bf00043874
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发表时间：
1994
影响因子：
5.1
通讯作者：
Mullet,JE
中科院分区：
文献类型：
--
作者：
Kim,J;Klein,PG;Mullet,JE
大麦的核基因突变体，vir-115，显示出发育诱导的D1合成的损失，导致光系统II的失活。从1小时光照的vir-115幼苗中分离的质体中的翻译与野生型相似。在野生型大麦中，照射植物16至72小时导致增加的放射性标记掺入15-24 kDa的D1翻译中间体。与此相反，这些D1翻译中间体中没有观察到的vir-115质体从植物照射16-72小时。此外，72小时的照明后，放射性标记掺入D1是不可检测的vir-115质体。从光照16-72 h的植物中分离的野生型和vir-115突变体质体中psbAmRNA在膜结合多聚核糖体中的水平和分布相似。足印分析显示，在vir-115和野生型质体中，psbAmRNA上的翻译起始复合物水平相似。这些结果表明，D1的翻译起始和延伸在突变体中没有显着改变。在野生型和vir-115突变体质体中观察到核糖体暂停onpsbAmRNA。因此，在突变体质体中D1翻译中间体的缺乏不是由于缺乏核糖体暂停onpsbAmRNA。基于这些结果，提出vir-115缺乏或含有通常稳定D1翻译中间体的修饰的核编码基因产物。在野生型质体中，核糖体暂停和稳定的D1翻译中间体，建议以促进组装的辅因子，如叶绿素将D1允许继续D1的合成和积累在成熟的叶绿体。
The nuclear gene mutant of barley, vir-115, shows a developmentally induced loss of D1 synthesis that results in inactivation of Photosystem II. Translation in plastids isolated from 1 h illuminated vir-115 seedlings is similar to wild type. In wild-type barley, illumination of plants for 16 to 72 h results in increased radiolabel incorporation into the D1 translation intermediates of 15–24 kDa. In contrast, these D1 translation intermediates were not observed in vir-115 plastids isolated from plants illuminated for 16–72 h. In addition, after 72 h of illumination, radiolabel incorporation into D1 was undetectable in vir-115 plastids. The level and distribution ofpsbAmRNA in membrane-associated polysomes was similar in wild-type and vir-115 mutant plastids isolated from plants illuminated for 16–72 h. Toeprint analysis showed similar levels of translation initiation complexes onpsbAmRNA in vir-115 and wild-type plastids. These results indicate that translation initiation and elongation of D1 is not significantly altered in the mutant plastids. Ribosome pausing onpsbAmRNA was observed in wild-type and vir-115 mutant plastids. Therefore, the absence of D1 translation intermediates in mutant plastids is not due to a lack of ribosome pausing onpsbAmRNA. Based on these results, it is proposed that vir-115 lacks or contains a modified nuclear-encoded gene product which normally stabilizes the D1 translation intermediates. In wild-type plastids, ribosome pausing and stabilization of D1 translation intermediates is proposed to facilitate assembly of cofactors such as chlorophyll will D1 allowing continued D1 synthesis and accumulation in mature chloroplasts.