A SecY homologue is required for the elaboration of the chloroplast thylakoid membrane and for normal chloroplast gene expression.
A SecY homologue is required for the elaboration of the chloroplast thylakoid membrane and for normal chloroplast gene expression.
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详细说明叶绿体类囊体膜和正常的叶绿体基因表达需要Secy同源物。
DOI：
10.1083/jcb.141.2.385
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发表时间：
1998-04-20
期刊：
影响因子：
--
通讯作者：
Barkan A
中科院分区：
文献类型：
--
作者：
Roy LM;Barkan A
体外和遗传学研究的结果为蛋白质靶向叶绿体类囊体膜的四种途径提供了证据。尽管这些途径最初由不同的底物参与并涉及一些不同的成分，但一个未解决的问题是多个途径是否会聚在膜中的一个共同的易位孔上。真细菌 SecY 的同源物称为 cpSecY，定位于类囊体膜。由于 SecY 是细菌中蛋白质转位孔的组成部分，因此 cpSecY 可能发挥类似的作用。为了探索 cpSecY 的作用，我们获得了在相应基因中插入转座子的玉米突变体。无效 cpSecY 突变体表现出类囊体膜的严重损失，在这方面与缺乏 cpSecA 的突变体不同。因此，cpSecY功能不限于cpSecA下游的易位步骤。 cpSecY 突变体的表型也比双突变体更具多效性，其中 cpSecA 和 ΔpH 依赖性类囊体靶向途径均被破坏。因此，cpSecY 的功能可能超出其在这些靶向途径中可能发挥的任何作用。 CpSecY 突变体还表现出叶绿体翻译缺陷，揭示了叶绿体膜生物发生和叶绿体基因表达之间的联系。
Results of in vitro and genetic studies have provided evidence for four pathways by which proteins are targeted to the chloroplast thylakoid membrane. Although these pathways are initially engaged by distinct substrates and involve some distinct components, an unresolved issue has been whether multiple pathways converge on a common translocation pore in the membrane. A homologue of eubacterial SecY called cpSecY is localized to the thylakoid membrane. Since SecY is a component of a protein-translocating pore in bacteria, cpSecY likely plays an analogous role. To explore the role of cpSecY, we obtained maize mutants with transposon insertions in the corresponding gene. Null cpSecY mutants exhibit a severe loss of thylakoid membrane, differing in this regard from mutants lacking cpSecA. Therefore, cpSecY function is not limited to a translocation step downstream of cpSecA. The phenotype of cpSecY mutants is also much more pleiotropic than that of double mutants in which both the cpSecA- and ΔpH-dependent thylakoid-targeting pathways are disrupted. Therefore, cpSecY function is likely to extend beyond any role it might play in these targeting pathways. CpSecY mutants also exhibit a defect in chloroplast translation, revealing a link between chloroplast membrane biogenesis and chloroplast gene expression.