Protein folding in the endoplasmic reticulum （ER） is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserv...Protein folding in the endoplasmic reticulum （ER） is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserved unfolded protein response （UPR） is initiated to mitigate the ER stress by enhancing the protein folding capability and/or accelerating the ER-associated protein degradation. Here, we report the conservation of the activation mechanism of OsbZIP74 （also known as OsbZIP50）, an important ER stress regulator in monocot plant rice （Oryza sativa L.）. Under normal conditions, OsbZIP74 mRNA encodes a basic leucine-zipper transcription factor with a putative transmembrane domain. When treating with ER stress-inducing agents such as tunicamycin and DTT, the conserved double stem-loop structures of OsbZIP74 mRNA are spliced out. Thereafter, the resulting new OsbZIP74 mRNA produces the nucleus-localized form of OsbZIP74 protein, eliminating the hydrophobic region. The activated form of OsbZIP74 has transcriptional activation activity in both yeast cells and Arabidopsis leaf protoplasts. The induction of OsbZIP74 splicing is much suppressed in the OsIRE1 knock- down rice plants, indicating the involvement of OslRE1 in OsbZIP74 splicing. We also demonstrate that the unconventional splicing of OsbZIP74 mRNA is associated with heat stress and salicylic acid, which is an important plant hormone in systemic acquired resistance against pathogen or parasite.展开更多
Tanshinones are a class of bioactive components in the traditional Chinese medicine Salvia miltiorrhiza, and their biosynthesis and regulation have been widely studied. Current studies show that basic leucine zipper(b...Tanshinones are a class of bioactive components in the traditional Chinese medicine Salvia miltiorrhiza, and their biosynthesis and regulation have been widely studied. Current studies show that basic leucine zipper(bZIP) proteins regulate plant secondary metabolism, growth and developmental processes. However, the b ZIP transcription factors involved in tanshinone biosynthesis are unknown.Here, we conducted the first genome-wide survey of the b ZIP gene family and analyzed the phylogeny,gene structure, additional conserved motifs and alternative splicing events in S. miltiorrhiza. A total of 70 Smb ZIP transcription factors were identified and categorized into 11 subgroups based on their phylogenetic relationships with those in Arabidopsis. Moreover, seventeen Smb ZIP genes underwent alternative splicing events. According to the transcriptomic data, the Smb ZIP genes that were highly expressed in the Danshen root and periderm were selected. Based on the prediction of b ZIP binding sites in the promoters and the co-expression analysis and co-induction patterns in response to Ag^+ treatment via quantitative real-time polymerase chain reaction(qRT-PCR), we concluded that Smb ZIP7 and Smb ZIP20 potentially participate in the regulation of tanshinone biosynthesis. These results provide a foundation for further functional characterization of the candidate Smb ZIP genes, which have the potential to increase tanshinone production.展开更多
Sugar signaling is a mechanism that plants use to integrate various internal and external cues to achieve nutrient homeostasis, mediate developmental programs, and articulate stress responses. Many bZlP transcription ...Sugar signaling is a mechanism that plants use to integrate various internal and external cues to achieve nutrient homeostasis, mediate developmental programs, and articulate stress responses. Many bZlP transcription factors are known to be involved in nutrient and/or stress signaling. An Arabidopsis Sl-group bZlP gene, AtbZIP1, was identified as a sugar-sensitive gene in a previous gene expression profiling study （Plant Cell. 16, 2128-2150）. In this report, we show that the expression of AtbZIP1 is repressed by sugars in a fast, sensitive, and reversible way. The sugar repression of Atb- ZIP1 is affected by a conserved sugar signaling component, hexokinase. Besides being a sugar-regulated gene, AtbZIP1 can mediate sugar signaling and affect gene expression, plant growth, and development. When carbon nutrients are limited, gain or loss of function of AtbZlP1 causes changes in the rates of early seedling establishment. Results of phenotypic analyses indicate that AtbZlP1 acts as a negative regulator of early seedling growth. Using gain- and loss-of-function plants in a microarray analysis, two sets of putative AtbZIP1-regulated genes have been identified. Among them, sugar-responsive genes are highly over-represented, implicating a role of AtbZlP1 in sugar-mediated gene expression. Using yeast two-hybrid （Y-2-H） screens and bimolecular fluorescence complementation （BiFC） analyses, we are able to recapitulate extensive C/S1 AtbZlP protein interacting network in living cells. Finally, we show that AtbZIP1 can bind ACGT-based motifs in vitro and that the binding characteristics appear to be affected by the heterodimerization between AtbZlP1 and the C-group AtbZIPs, including AtbZlP10 and AtbZlP63.展开更多
The basic leucine zipper （bZIP） transcription factors form a large gene family that is important in pathogen defense, light and stress signaling, etc. The Completed whole genome sequences of model plants Arabidopsis...The basic leucine zipper （bZIP） transcription factors form a large gene family that is important in pathogen defense, light and stress signaling, etc. The Completed whole genome sequences of model plants Arabidopsis （Arabidopsis thaliana）, rice （Oryza sativa） and poplar （Populus trichocarpa） constitute a valuable resource for genome-wide analysis and genomic comparative analysis, as they are representatives of the two major evolutionary lineages within the angiosperms： the monocotyledons and the dicotyledons. In this study, bioinformatics analysis identified 74, 89 and 88 bZIP genes respectively in Arabidopsis, rice and poplar. Moreover, a comprehensive overview of this gene family is presented, including the gene structure, phylogeny, chromosome distribution, conserved motifs. As a result, the plant bZIPs were organized into 10 subfamilies on basis of phylogenetic relationship. Gene duplication events during the family evolution history were also investigated. And it was further concluded that chromosomal/segmental duplication might have played a key role in gene expansion of bZIP gene family.展开更多
基金This project is funded by the National Natural Science Foundation of China （31070233, 31171157）, Shanghai Pujiang Talent Program （11PJ1400700）, and partly supported by the National Basic Research Program of China （973 Program, 2012CB910500）, all granted to J.X.L. ACKNOWLEDGMENTS We would also like thank Drs Yuhya Wakasa and Fumio Takaiwa for providing the OslREI transgenic rice seeds. No conflict of interest declared.
文摘Protein folding in the endoplasmic reticulum （ER） is a fundamental process in plant cells that is vulnerable to many environmental stresses. When unfolded or misfolded proteins accumulate in the ER, the well-conserved unfolded protein response （UPR） is initiated to mitigate the ER stress by enhancing the protein folding capability and/or accelerating the ER-associated protein degradation. Here, we report the conservation of the activation mechanism of OsbZIP74 （also known as OsbZIP50）, an important ER stress regulator in monocot plant rice （Oryza sativa L.）. Under normal conditions, OsbZIP74 mRNA encodes a basic leucine-zipper transcription factor with a putative transmembrane domain. When treating with ER stress-inducing agents such as tunicamycin and DTT, the conserved double stem-loop structures of OsbZIP74 mRNA are spliced out. Thereafter, the resulting new OsbZIP74 mRNA produces the nucleus-localized form of OsbZIP74 protein, eliminating the hydrophobic region. The activated form of OsbZIP74 has transcriptional activation activity in both yeast cells and Arabidopsis leaf protoplasts. The induction of OsbZIP74 splicing is much suppressed in the OsIRE1 knock- down rice plants, indicating the involvement of OslRE1 in OsbZIP74 splicing. We also demonstrate that the unconventional splicing of OsbZIP74 mRNA is associated with heat stress and salicylic acid, which is an important plant hormone in systemic acquired resistance against pathogen or parasite.
基金supported by the National Natural Science Foundation (Grant No.81573398)Chinese Academy of Medical Sciences(CAMS)Innovation Fund for Medical Sciences (CIFMS,2016-I2M-3–016)
文摘Tanshinones are a class of bioactive components in the traditional Chinese medicine Salvia miltiorrhiza, and their biosynthesis and regulation have been widely studied. Current studies show that basic leucine zipper(bZIP) proteins regulate plant secondary metabolism, growth and developmental processes. However, the b ZIP transcription factors involved in tanshinone biosynthesis are unknown.Here, we conducted the first genome-wide survey of the b ZIP gene family and analyzed the phylogeny,gene structure, additional conserved motifs and alternative splicing events in S. miltiorrhiza. A total of 70 Smb ZIP transcription factors were identified and categorized into 11 subgroups based on their phylogenetic relationships with those in Arabidopsis. Moreover, seventeen Smb ZIP genes underwent alternative splicing events. According to the transcriptomic data, the Smb ZIP genes that were highly expressed in the Danshen root and periderm were selected. Based on the prediction of b ZIP binding sites in the promoters and the co-expression analysis and co-induction patterns in response to Ag^+ treatment via quantitative real-time polymerase chain reaction(qRT-PCR), we concluded that Smb ZIP7 and Smb ZIP20 potentially participate in the regulation of tanshinone biosynthesis. These results provide a foundation for further functional characterization of the candidate Smb ZIP genes, which have the potential to increase tanshinone production.
基金This work was supported by The National Science Foundation （IOB- 0543751 to J.C.J.）.We thank the Arabidopsis Biological Resource Center （Columbus, Ohio） for providing DNA clones and seeds, Dr Biao Ding formicroscopy facility, Dr Steven St Martin for microarray design and data analysis, Cyrus Hah for protoplast transient expression analysis, Drs John Finer and Michelle Jones for critical reading of the manuscript, and Joe Takayama for greenhouse support. No conflict of interest declared.
文摘Sugar signaling is a mechanism that plants use to integrate various internal and external cues to achieve nutrient homeostasis, mediate developmental programs, and articulate stress responses. Many bZlP transcription factors are known to be involved in nutrient and/or stress signaling. An Arabidopsis Sl-group bZlP gene, AtbZIP1, was identified as a sugar-sensitive gene in a previous gene expression profiling study （Plant Cell. 16, 2128-2150）. In this report, we show that the expression of AtbZIP1 is repressed by sugars in a fast, sensitive, and reversible way. The sugar repression of Atb- ZIP1 is affected by a conserved sugar signaling component, hexokinase. Besides being a sugar-regulated gene, AtbZIP1 can mediate sugar signaling and affect gene expression, plant growth, and development. When carbon nutrients are limited, gain or loss of function of AtbZlP1 causes changes in the rates of early seedling establishment. Results of phenotypic analyses indicate that AtbZlP1 acts as a negative regulator of early seedling growth. Using gain- and loss-of-function plants in a microarray analysis, two sets of putative AtbZIP1-regulated genes have been identified. Among them, sugar-responsive genes are highly over-represented, implicating a role of AtbZlP1 in sugar-mediated gene expression. Using yeast two-hybrid （Y-2-H） screens and bimolecular fluorescence complementation （BiFC） analyses, we are able to recapitulate extensive C/S1 AtbZlP protein interacting network in living cells. Finally, we show that AtbZIP1 can bind ACGT-based motifs in vitro and that the binding characteristics appear to be affected by the heterodimerization between AtbZlP1 and the C-group AtbZIPs, including AtbZlP10 and AtbZlP63.
文摘The basic leucine zipper （bZIP） transcription factors form a large gene family that is important in pathogen defense, light and stress signaling, etc. The Completed whole genome sequences of model plants Arabidopsis （Arabidopsis thaliana）, rice （Oryza sativa） and poplar （Populus trichocarpa） constitute a valuable resource for genome-wide analysis and genomic comparative analysis, as they are representatives of the two major evolutionary lineages within the angiosperms： the monocotyledons and the dicotyledons. In this study, bioinformatics analysis identified 74, 89 and 88 bZIP genes respectively in Arabidopsis, rice and poplar. Moreover, a comprehensive overview of this gene family is presented, including the gene structure, phylogeny, chromosome distribution, conserved motifs. As a result, the plant bZIPs were organized into 10 subfamilies on basis of phylogenetic relationship. Gene duplication events during the family evolution history were also investigated. And it was further concluded that chromosomal/segmental duplication might have played a key role in gene expansion of bZIP gene family.
