Activation of the heterotrimeric G protein alpha-subunit GPA1 suppresses the ftsh-mediated inhibition of chloroplast development in Arabidopsis.
Activation of the heterotrimeric G protein alpha-subunit GPA1 suppresses the ftsh-mediated inhibition of chloroplast development in Arabidopsis.
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DOI：
10.1111/j.1365-313x.2009.03843.x
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发表时间：
2009-06
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影响因子：
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通讯作者：
Lingang Zhang;Qing Wei;Wenjuan Wu;Yuxiang Cheng;G. Hu;Fenhong Hu;Yi Sun;Yin‐Min Zhu;W. Sakamoto;Jirong Huang
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文献类型：
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作者：
Lingang Zhang;Qing Wei;Wenjuan Wu;Yuxiang Cheng;G. Hu;Fenhong Hu;Yi Sun;Yin‐Min Zhu;W. Sakamoto;Jirong Huang
异源三聚体G蛋白敲除突变体在叶绿体发育中没有表型缺陷，并且G蛋白信号传导途径与叶绿体发育之间的联系仅从药学证据中推断。因此，G蛋白信号是否在叶绿体发育中起作用仍然是一个悬而未决的问题。在这里，我们提出的遗传证据，使用叶杂色突变体类囊体形成1（thf 1），表明内源性G蛋白α-亚基（GPA 1）的失活或激活影响叶绿体发育，因为这样的异位表达的组成型活性的α-亚基（cGPA 1）。分子生物学和遗传分析表明，FtsH复合物，这是由A型（FtsH 1/FtsH 5）和B型（FtsH 2/FtsH 8）亚基，cGPA 1促进叶绿体发育所需的thf 1。此外，cGPA 1的异位表达挽救了ftsh 2的叶斑。与这一发现相一致，微阵列分析表明，cGPA 1的异位表达部分纠正了thf 1中错误调节的基因表达。这种被忽视的G蛋白功能为我们理解整合信号网络提供了新的见解，该网络动态调节叶绿体发育和功能，以响应细胞内和细胞外信号。
Heterotrimeric G protein knock-out mutants have no phenotypic defect in chloroplast development, and the connection between the G protein signaling pathway and chloroplast development has only been inferred from pharmaceutical evidence. Thus, whether G protein signaling plays a role in chloroplast development remains an open question. Here, we present genetic evidence, using the leaf-variegated mutant thylakoid formation 1 (thf1), indicating that inactivation or activation of the endogenous G protein alpha-subunit (GPA1) affects chloroplast development, as does the ectopic expression of the constitutively active Galpha-subunit (cGPA1). Molecular biological and genetic analyses showed that FtsH complexes, which are composed of type-A (FtsH1/FtsH5) and type-B (FtsH2/FtsH8) subunits, are required for cGPA1-promoted chloroplast development in thf1. Furthermore, the ectopic expression of cGPA1 rescues the leaf variegation of ftsh2. Consistent with this finding, microarray analysis shows that ectopic expression of cGPA1 partially corrects mis-regulated gene expression in thf1. This overlooked function of G proteins provides new insight into our understanding of the integrative signaling network, which dynamically regulates chloroplast development and function in response to both intracellular and extracellular signals.