Blue light-induced transcription of plastid-encoded psbD gene is mediated by a nuclear-encoded transcription initiation factor, AtSig5.
Blue light-induced transcription of plastid-encoded psbD gene is mediated by a nuclear-encoded transcription initiation factor, AtSig5.
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DOI：
10.1073/pnas.0308362101
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发表时间：
2004-03
影响因子：
11.1
通讯作者：
Y. Tsunoyama;Y. Ishizaki;K. Morikawa;M. Kobori;Y. Nakahira;G. Takeba;Y. Toyoshima;T. Shiina
中科院分区：
文献类型：
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作者：
Y. Tsunoyama;Y. Ishizaki;K. Morikawa;M. Kobori;Y. Nakahira;G. Takeba;Y. Toyoshima;T. Shiina
光是调控光合作用基因表达的重要环境因子之一。编码光系统II反应中心蛋白D2的质体psbD基因在由细菌型质体RNA聚合酶（PEP）转录的独特蓝光响应启动子（BLRP）的控制下。PEP的启动子识别由拟南芥中六种核编码的σ因子之一介导。与PEP相关的质体σ因子的替换可能是质体转录模式响应环境和发育信号的主要机制。这项研究表明，AtSig 5是一个独特的sigma因子，对于psbD BLRP活性至关重要。AtSIG 5表达降低的T-DNA插入突变体导致psbD BLRP的初级转录物丢失。此外，AtSig 5在暗适应原生质体中的瞬时过表达特异性地提高了psbD和psbA的转录活性。另一方面，过量表达AtSig 2可促进psbA基因和trnE操纵子的转录，但对psbD的转录没有影响。AtSIG 5基因在遗传学上与其他质体σ因子不同，并且其表达仅由蓝光诱导。我们提出AtSig 5作为蓝光信号传导的介体，特异性地激活拟南芥中响应蓝光的psbD BLRP。
Light is one of the most important environmental factors regulating expression of photosynthesis genes. The plastid psbD gene encoding the photosystem II reaction center protein D2 is under the control of a unique blue light responsive promoter (BLRP) that is transcribed by a bacterial-type plastid RNA polymerase (PEP). Promoter recognition of PEP is mediated by one of the six nuclear-encoded sigma factors in Arabidopsis. The replacement of the plastid sigma factor associated with PEP may be the major mechanism for switching of plastid transcription pattern in response to environmental and developmental signals. This study demonstrates that AtSig5 is a unique sigma factor that is essential for psbD BLRP activity. A T-DNA insertional mutant with reduced AtSIG5 expression resulted in loss of primary transcripts from the psbD BLRP. Furthermore, transient overexpression of AtSig5 in dark-adapted protoplasts specifically elevated psbD and psbA transcription activities. On the other hand, overproduction of AtSig2 enhanced the transcription of psbA gene and trnE operon, but not psbD transcription. The AtSIG5 gene is phylogenetically distinct from other plastid sigma factors, and its expression is induced exclusively by blue light. We propose that AtSig5 acts as a mediator of blue light signaling that specifically activates the psbD BLRP in response to blue light in Arabidopsis.