Sigma factor-mediated plastid retrograde signals control nuclear gene expression.
Sigma factor-mediated plastid retrograde signals control nuclear gene expression.
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DOI：
10.1111/tpj.12011
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发表时间：
2013-01
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影响因子：
--
通讯作者：
Chory J
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文献类型：
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作者：
Woodson JD;Perez-Ruiz JM;Schmitz RJ;Ecker JR;Chory J
在光自养和环境条件波动的过程中，从质体到细胞核的逆行信号对于调节细胞器的蛋白质组是必要的。使用叶绿体生物发生抑制剂的研究表明，数百个核基因受到质体发出的逆行信号的调节。质体基因表达是这些信号中至少一种的来源，但用于调节核基因表达的信号的数量及其机制尚不清楚。为了进一步研究质体基因表达对核基因表达的影响，我们分析了拟南芥突变体，这些突变体在六个西格玛因子（SIG）基因中的每一个都有缺陷，这些基因编码质体编码的RNA聚合酶利用的蛋白质来转录特定的质体基因组。我们发现 SIG2 和 SIG6 在质体转录和逆行信号控制核基因表达中具有部分冗余的作用。 GUN1（质体定位的五肽重复蛋白）的丢失能够恢复 sig2 和 sig6 中的核（但不能质体）基因表达，而血红素合成的增加只能恢复 sig2 突变体中的核基因表达。这些结果表明，西格玛因子功能是至少两个向细胞核逆行信号的来源；一种可能涉及 tRNAGlu 的转录。微阵列分析表明，这两个信号至少占核基因的一个子集，这些基因受质体生物发生抑制剂诺氟拉松和林可霉素的调节。这些数据共同表明，此类抑制剂可以通过影响质体中的转录来诱导逆行信号传导。
Retrograde signalling from plastids to the nucleus is necessary to regulate the organelle’s proteome during the establishment of photoautotrophy and fluctuating environmental conditions. Studies that used inhibitors of chloroplast biogenesis have revealed that hundreds of nuclear genes are regulated by retrograde signals emitted from plastids. Plastid gene expression is the source of at least one of these signals, but the number of signals and their mechanisms used to regulate nuclear gene expression are unknown. To further examine the effects of plastid gene expression on nuclear gene expression, we analyzed Arabidopsis mutants that were defective in each of the six sigma factor (SIG) genes that encode proteins utilized by plastid-encoded RNA polymerase to transcribe specific sets of plastid genes. We showed that SIG2 and SIG6 have partially redundant roles in plastid transcription and retrograde signalling to control nuclear gene expression. The loss of GUN1 (a plastid-localized pentatricopeptide repeat protein) is able to restore nuclear (but not plastid) gene expression in both sig2 and sig6, whereas an increase in heme synthesis is able to restore nuclear gene expression in sig2 mutants only. These results demonstrate that sigma factor function is the source of at least two retrograde signals to the nucleus; one likely to involve the transcription of tRNAGlu. A microarray analysis showed that these two signals accounted for at least one subset of the nuclear genes that are regulated by the plastid biogenesis inhibitors norflurazon and lincomycin. Together these data suggest that such inhibitors can induce retrograde signalling by affecting transcription in the plastid.