期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2010
卷号：107
期号：23
页码：10760-10764
DOI：10.1073/pnas.0911692107
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：An imbalance in photosynthetic electron transfer is thought to be redressed by photosynthetic control of the rate of expression of genes encoding apoproteins of photosystem (PS)-I and PS-II in response to the redox state of plastoquinone (PQ), which is a connecting electron carrier. PS stoichiometry is then adjusted to enhance photosynthetic efficiency. In prokaryotes, sigma factors are well known for their participation in the control of RNA polymerase activity in transcription, whereas there have been no reports concerning their association with redox regulation. We have found that the phosphorylation of SIG1, the major sigma factor (SIG), is regulated by redox signals and selectively inhibits the transcription of the psaA gene, which encodes a PS-I protein. We produced transgenic Arabidopsis plants with or without the putative phosphorylation sites for SIG1 and demonstrated through in vivo labeling that Thr-170 was involved in the phosphorylation. We analyzed the in vivo and in vitro transcriptional responses of the transgenic Arabidopsis plants to the redox status in regard to involvement of the phosphorylation site. We revealed an enhanced phosphorylation of SIG1 under oxidative conditions of PQ in a form associated with the molecular mass of the holoenzyme. Phosphorylation of SIG1 proved crucial through a change in the promoter specificity for sustaining balanced expression of components in PS-I and PS-II and was responsible for harmonious electron flow to maintain photosynthetic efficiency.
