Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Óleos de Plantas , Sementes/genética , Sementes/metabolismo , Regulação da Expressão Gênica de Plantas , Plantas Geneticamente Modificadas/metabolismoRESUMO
Vegetable oils are not only major components of human diet but also vital for industrial applications. WRINKLED1 (WRI1) is a pivotal transcription factor governing plant oil biosynthesis, but the underlying DNA-binding mechanism remains incompletely understood. Here, we resolved the structure of Arabidopsis WRI1 (AtWRI1) with its cognate double-stranded DNA (dsDNA), revealing two antiparallel ß sheets in the tandem AP2 domains that intercalate into the adjacent major grooves of dsDNA to determine the sequence recognition specificity. We showed that AtWRI1 represented a previously unidentified structural fold and DNA-binding mode. Mutations of the key residues interacting with DNA element affected its binding affinity and oil biosynthesis when these variants were transiently expressed in tobacco leaves. Seed oil content was enhanced in stable transgenic wri1-1 expressing an AtWRI1 variant (W74R). Together, our findings offer a structural basis explaining WRI1 recognition and binding of DNA and suggest an alternative strategy to increase oil yield in crops through WRI1 bioengineering.
Assuntos
Proteínas de Arabidopsis , Arabidopsis , Arabidopsis/genética , Arabidopsis/metabolismo , Proteínas de Arabidopsis/genética , Proteínas de Arabidopsis/metabolismo , Regulação da Expressão Gênica de Plantas , Humanos , Óleos de Plantas/metabolismo , Plantas Geneticamente Modificadas/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
Plants produce and accumulate triacylglycerol (TAG) in their seeds as an energy reservoir to support the processes of seed germination and seedling development. Plant seed oils are vital not only for the human diet but also as renewable feedstocks for industrial use. TAG biosynthesis consists of two major steps: de novo fatty acid biosynthesis in the plastids and TAG assembly in the endoplasmic reticulum. The latest advances in unraveling transcriptional regulation have shed light on the molecular mechanisms of plant oil biosynthesis. We summarize recent progress in understanding the regulatory mechanisms of well-characterized and newly discovered transcription factors and other types of regulators that control plant fatty acid biosynthesis. The emerging picture shows that plant oil biosynthesis responds to developmental and environmental cues that stimulate a network of interacting transcriptional activators and repressors, which in turn fine-tune the spatiotemporal regulation of the pathway genes.
Assuntos
Regulação da Expressão Gênica de Plantas , Óleos de Plantas , Plantas , Ácidos Graxos/metabolismo , Óleos de Plantas/metabolismo , Plantas/genética , Plantas/metabolismo , Sementes/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Triglicerídeos/metabolismoRESUMO
Sunflower (Helianthus annuus) is one of the most important oilseed crops worldwide. However, the transcriptional regulation underlying oil accumulation in sunflower is not fully understood. WRINKLED1 (WRI1) is an essential transcription factor governing oil accumulation in plant cells. Here, we identify and characterize a sunflower ortholog of WRI1 (HaWRI1), which is highly expressed in developing seeds. Transient production of HaWRI1 stimulated substantial oil accumulation in Nicotiana benthamiana leaves. Dual-luciferase reporter assay, electrophoretic mobility shift assay, fatty acid quantification, and gene expression analysis demonstrate that HaWRI1 acts as a pivotal transcription factor controlling the expression of genes involved in late glycolysis and fatty acid biosynthesis. HaWRI1 directly binds to the cis-element, AW-box, in the promoter of biotin carboxyl carrier protein isoform 2 (BCCP2). In addition, we characterize an 80 amino-acid C-terminal domain of HaWRI1 that is crucial for transactivation. Moreover, seed-specific overexpression of HaWRI1 in Arabidopsis plants leads to enhanced seed oil content as well as upregulation of the genes involved in fatty acid biosynthesis. Taken together, our work demonstrates that HaWRI1 plays a pivotal role in the transcriptional control of seed oil accumulation, providing a potential target for bioengineering sunflower oil yield improvement.