Repression of Essential Chloroplast Genes Reveals New Signaling Pathways and Regulatory Feedback Loops in Chlamydomonas
Repression of Essential Chloroplast Genes Reveals New Signaling Pathways and Regulatory Feedback Loops in Chlamydomonas
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DOI：
10.1105/tpc.112.103051
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发表时间：
2013-01-01
期刊：
影响因子：
11.6
通讯作者：
Rochaix, Jean-David
中科院分区：
文献类型：
--
作者：
Ramundo, Silvia;Rahire, Michele;Rochaix, Jean-David
虽然反向遗传学已被用于阐明许多叶绿体蛋白的功能，但尚未实现基本质体基因的特征及其在叶绿体生物发生和细胞存活中的作用。因此，我们在单细胞藻莱因哈衣藻中建立了一个基于维生素抑制核糖体开关的强大的叶绿体抑制基因表达系统，并利用该系统研究了两个必需的叶绿体基因：编码质体核糖体蛋白的核糖体蛋白S12 （rps12）和编码叶绿体细菌样RNA聚合酶a亚基的rpoA的作用。抑制这两个基因中的任何一个都会导致细胞生长停滞，并引起涉及叶绿体生物发生、蛋白质周转和应激的核基因表达变化的反应。这种反应也导致了一些质体转录物的过度积累，并揭示了叶绿体基因回路中存在多个负调节反馈回路。
Although reverse genetics has been used to elucidate the function of numerous chloroplast proteins, the characterization of essential plastid genes and their role in chloroplast biogenesis and cell survival has not yet been achieved. Therefore, we developed a robust repressible chloroplast gene expression system in the unicellular alga Chlamydomonas reinhardtii based mainly on a vitamin-repressible riboswitch, and we used this system to study the role of two essential chloroplast genes: ribosomal protein S12 (rps12), encoding a plastid ribosomal protein, and rpoA, encoding the a-subunit of chloroplast bacterial-like RNA polymerase. Repression of either of these two genes leads to the arrest of cell growth, and it induces a response that involves changes in expression of nuclear genes implicated in chloroplast biogenesis, protein turnover, and stress. This response also leads to the overaccumulation of several plastid transcripts and reveals the existence of multiple negative regulatory feedback loops in the chloroplast gene circuitry.