RESUMO
Stenocereus queretaroensis (F.A.C. Weber ex Mathes.) Buxb is a cactus that has long been used as a source food in central and northern México. Its fruits, commonly called pitayas, biosynthesize high amounts of betalains. These molecules are water-soluble nitrogenous compounds; that compared to other pigments, such as anthocyanins or carotenoids, stand out for their physicochemical stability in industrial processes. Due to genetic and environmental factors involved in the biosynthesis and accumulation of secondary metabolites in plants, we tested different stress-inducing agents (elicitor, osmotic, salt, and temperature) to induce betalains accumulation in cell culture from fruits of Stenocereus queretaroensis. This work aimed to understand stress conditions that induce the metabolic pathways required for the accumulation of betalains. The results show how betacyanin concentration increases under high sugar conditions, thus affecting the expression of L-DOPA 4, 5 dioxygenase resulting in a strong dark red coloration. This suggests this enzyme is part of a rate-limiting step in betalain production. In addition, we found that betalains accumulation occurs under particular stress conditions. Cells that have a high level of betacyanins show better resistance to stress in the cell culture, as well as an overall different behavior including cell aggregation and alterations in nuclear size. Together the results shown here may provide new strategies to manipulate and mass produce the pigments from Stenocereus queretaroensis in cell culture.
RESUMO
The process of phase separation allows for the establishment and formation of subcompartmentalized structures, thus enabling cells to perform simultaneous processes with precise organization and low energy requirements. Chemical modifications of proteins, RNA, and lipids alter the molecular environment facilitating enzymatic reactions at higher concentrations in particular regions of the cell. In this review, we discuss the nucleolus as an example of the establishment, dynamics, and maintenance of a membraneless organelle with a high level of organization.
Assuntos
Nucléolo Celular/metabolismo , Proteínas Intrinsicamente Desordenadas/isolamento & purificação , Proteínas Intrinsicamente Desordenadas/metabolismo , Regulação da Expressão Gênica , Humanos , Extração Líquido-Líquido , Proteínas Nucleares/isolamento & purificação , Proteínas Nucleares/metabolismoRESUMO
Fibrillarin is a highly conserved nucleolar methyltransferase responsible for ribosomal RNA methylation across evolution from Archaea to humans. It has been reported that fibrillarin is involved in the methylation of histone H2A in nucleoli and other processes, including viral progression, cellular stress, nuclear shape, and cell cycle progression. We show that fibrillarin has an additional activity as a ribonuclease. The activity is affected by phosphoinositides and phosphatidic acid and insensitive to ribonuclease inhibitors. Furthermore, the presence of phosphatidic acid releases the fibrillarin-U3 snoRNA complex. We show that the ribonuclease activity localizes to the GAR (glycine/arginine-rich) domain conserved in a small group of RNA interacting proteins. The introduction of the GAR domain occurred in evolution in the transition from archaea to eukaryotic cells. The interaction of this domain with phospholipids may allow a phase separation of this protein in nucleoli.
Assuntos
Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/metabolismo , Fosfolipídeos/metabolismo , Ribonucleases/química , Ribonucleases/metabolismo , Proteínas Cromossômicas não Histona/genética , Células HeLa , Humanos , Mutação/genética , Domínios Proteicos , RNA Nucleolar Pequeno/metabolismo , Proteínas Recombinantes/metabolismo , Ribonucleases/genética , Ribonucleoproteínas/metabolismo , Relação Estrutura-AtividadeRESUMO
Phosphoinositides are very versatile molecules with a plethora of functions such as cytokinesis, chemotaxis, cell survival, and cell death. Their functions depend on the proteins with which they interact. Thus, when interacting with phospholipases, phosphatases, or kinases, they can be precursors of second messengers in different signalling pathways. They could be second messengers themselves and interact directly with other proteins to modulate their functions trough changing its localization and activity or enhancing its synthesis rate. Because they are more abundant in animal cells and their importance in diseases such as cancer has taken priority, the study of the phosphoinositides in plants has not evolved to the same extent. Nevertheless, several studies have shown the significance of these lipids in plant cells viability and environmental response. This review focuses on phosphoinositides response to abiotic and biotic stress, showing their implication in plant survival during different stages of development. SIGNIFICANCE OF THE STUDY: This review is focused on plant PIPs functions in stress, highlighting in the main differences between plant and mammal PIPs and the novel interactions that could be extrapolated to animal models to contribute in a better understanding of these pivotal molecules.
Assuntos
Fosfatidilinositóis/metabolismo , Plantas/metabolismo , Fosfatidilinositóis/química , Plantas/química , Estresse FisiológicoRESUMO
Plants respond to drought stress through the ABA dependent and independent pathways, which in turn modulate transcriptional regulatory hubs. Here, we employed Illumina RNA-Seq to analyze a total of 18 cDNA libraries from leaves, sap, and roots of papaya plants under drought stress. Reference and de novo transcriptomic analyses identified 8,549 and 6,089 drought-responsive genes and unigenes, respectively. Core sets of 6 and 34 genes were simultaneously up- or down-regulated, respectively, in all stressed samples. Moreover, GO enrichment analysis revealed that under moderate drought stress, processes related to cell cycle and DNA repair were up-regulated in leaves and sap; while responses to abiotic stress, hormone signaling, sucrose metabolism, and suberin biosynthesis were up-regulated in roots. Under severe drought stress, biological processes related to abiotic stress, hormone signaling, and oxidation-reduction were up-regulated in all tissues. Moreover, similar biological processes were commonly down-regulated in all stressed samples. Furthermore, co-expression network analysis revealed three and eight transcriptionally regulated modules in leaves and roots, respectively. Seventeen stress-related TFs were identified, potentially serving as main regulatory hubs in leaves and roots. Our findings provide insight into the molecular responses of papaya plant to drought, which could contribute to the improvement of this important tropical crop.
Assuntos
Carica/genética , Regulação da Expressão Gênica de Plantas , Aclimatação , Carica/fisiologia , Reparo do DNA , Secas , Redes Reguladoras de Genes , Transdução de Sinais , Estresse Fisiológico , TranscriptomaRESUMO
Fibrillarin is an essential protein that is well known as a molecular marker of transcriptionally active RNA polymerase I. Fibrillarin methyltransferase activity is the primary known source of methylation for more than 100 methylated sites involved in the first steps of preribosomal processing and required for structural ribosome stability. High expression levels of fibrillarin have been observed in several types of cancer cells, particularly when p53 levels are reduced, because p53 is a direct negative regulator of fibrillarin transcription. Here, we show fibrillarin domain conservation, structure and interacting molecules in different cellular processes as well as with several viral proteins during virus infection.
Assuntos
Archaea/genética , Archaea/metabolismo , Proteínas Cromossômicas não Histona/genética , Proteínas Cromossômicas não Histona/metabolismo , Animais , Humanos , Metilação , Neoplasias/genética , Neoplasias/metabolismoRESUMO
RNA polymerase IV and V are principal players in the RdDM pathway, where their current study has shown interaction of several factors that control DNA silencing of intergenic regions and siRNA production. DNA silencing is an important process during cell differentiation, nuclear structure and viral control. However, RNA pol IV and V are yet to be study in model monocot systems like Oryza sativa that can provide further information on genetic silence mechanism in plats. We show the expression pattern of these polymerases in tissues extracts of Oryza sativa. Detectable amounts of these polymerases are found in specific adult plant tissues and particularly expressed during somatic embryogenesis but not during early stages of normal embryo development. The use of synthetic auxin leads to an induction of both RNA pol IV and V in scutellum tissue where nuclear localization may be required for genome reorganization and gene silencing.