Structure and expression analysis of three subtypes of< i> Arabidopsis MBF1 genes (original) (raw)
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The plant MBF1 protein family: a bridge between stress and transcription
Journal of Experimental Botany
The Multiprotein Bridging Factor 1 (MBF1) proteins are transcription co-factors whose molecular function is to form a bridge between transcription factors and the basal machinery of transcription. MBF1s are present in most archaea and all eukaryotes, and numerous reports show that they are involved in developmental processes and in stress responses. In this review we summarize almost three decades of research on the plant MBF1 family, which has mainly focused on their role in abiotic stress responses, in particular the heat stress response. However, despite the amount of information available, there are still many questions that remain about how plant MBF1 genes, transcripts, and proteins respond to stress, and how they in turn modulate stress response transcriptional pathways.
Plant and cell …, 2004
Multiprotein bridging factor 1 (MBF1) is known to be a transcriptional co-activator that mediates transcriptional activation by bridging between an activator and a TATAbox binding protein (TBP). We demonstrated that expression of every three MBF1 from Arabidopsis partially rescues the yeast mbf1 mutant phenotype, indicating that all of them function as co-activators for GCN4-dependent transcriptional activation. We also report that each of their subtypes shows distinct tissue-specific expression patterns and responses to phytohormones. These observations suggest that even though they share a similar biochemical function, each MBF1 has distinct roles in various tissues and conditions.
Journal of Plant Physiology, 2010
Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) type belong to a small multigenic family that controls gene expression by connecting transcription factors and the basal transcription machinery. In this report, a triple knock-down mutant (abc À ) for the Arabidopsis thaliana MBF1 genes AtMBF1a, AtMBF1b and AtMBF1c was generated. The phenotypic characterization using oxidative agents such as hydrogen peroxide and methyl viologen revealed that the abc À mutant was more sensitive to oxidative stress. The triple knock-down mutant, abc À was also sensitive to osmotic stress mediated by high concentrations of sorbitol. Furthermore, the abc À phenotype was partially or completely rescued by AtMBF1c cDNA over-expression (abc À + c) depending on physiological and developmental conditions. AtMBF1s regulate the expression of ABR1, which is a member of the ethyleneresponse factor family and acts as ABA repressor. Thus, we conclude that AtMBF1 gene family may function as a regulatory component of the cross-talk node between ethylene, ABA and stress signal pathways. Furthermore, higher levels of a HSP70 mRNA and an immunoreactive HSP70 protein were detected in the abc À mutant. The participation of MBF1c as a possible negative regulator of HSP genes was discussed.
Journal of Plant Physiology, 2010
Transcriptional co-activators of the multiprotein bridging factor 1 (MBF1) type belong to a small multigenic family that controls gene expression by connecting transcription factors and the basal transcription machinery. In this report, a triple knock-down mutant (abc À ) for the Arabidopsis thaliana MBF1 genes AtMBF1a, AtMBF1b and AtMBF1c was generated. The phenotypic characterization using oxidative agents such as hydrogen peroxide and methyl viologen revealed that the abc À mutant was more sensitive to oxidative stress. The triple knock-down mutant, abc À was also sensitive to osmotic stress mediated by high concentrations of sorbitol. Furthermore, the abc À phenotype was partially or completely rescued by AtMBF1c cDNA over-expression (abc À + c) depending on physiological and developmental conditions. AtMBF1s regulate the expression of ABR1, which is a member of the ethyleneresponse factor family and acts as ABA repressor. Thus, we conclude that AtMBF1 gene family may function as a regulatory component of the cross-talk node between ethylene, ABA and stress signal pathways. Furthermore, higher levels of a HSP70 mRNA and an immunoreactive HSP70 protein were detected in the abc À mutant. The participation of MBF1c as a possible negative regulator of HSP genes was discussed.
Plant Cell, 2002
Numerous studies have shown that transcription factors are important in regulating plant responses to environmental stress. However, specific functions for most of the genes encoding transcription factors are unclear. In this study, we used mRNA profiles generated from microarray experiments to deduce the functions of genes encoding known and putative Arabidopsis transcription factors. The mRNA levels of 402 distinct transcription factor genes were examined at different developmental stages and under various stress conditions. Transcription factors potentially controlling downstream gene expression in stress signal transduction pathways were identified by observed activation and repression of the genes after certain stress treatments. The mRNA levels of a number of previously characterized transcription factor genes were changed significantly in connection with other regulatory pathways, suggesting their multifunctional nature. The expression of 74 transcription factor genes responsive to bacterial pathogen infection was reduced or abolished in mutants that have defects in salicylic acid, jasmonic acid, or ethylene signaling. This observation indicates that the regulation of these genes is mediated at least partly by these plant hormones and suggests that the transcription factor genes are involved in the regulation of additional downstream responses mediated by these hormones. Among the 43 transcription factor genes that are induced during senescence, 28 of them also are induced by stress treatment, suggesting extensive overlap responses to these stresses. Statistical analysis of the promoter regions of the genes responsive to cold stress indicated unambiguous enrichment of known conserved transcription factor binding sites for the responses. A highly conserved novel promoter motif was identified in genes responding to a broad set of pathogen infection treatments. This observation strongly suggests that the corresponding transcription factors play general and crucial roles in the coordinated regulation of these specific regulons. Although further validation is needed, these correlative results provide a vast amount of information that can guide hypothesis-driven research to elucidate the molecular mechanisms involved in transcriptional regulation and signaling networks in plants.
PLANT PHYSIOLOGY, 2005
Abiotic stresses cause extensive losses to agricultural production worldwide. Acclimation of plants to abiotic conditions such as drought, salinity, or heat is mediated by a complex network of transcription factors and other regulatory genes that control multiple defense enzymes, proteins, and pathways. Associated with the activity of different transcription factors are transcriptional coactivators that enhance their binding to the basal transcription machinery. Although the importance of stress-response transcription factors was demonstrated in transgenic plants, little is known about the function of transcriptional coactivators associated with abiotic stresses. Here, we report that constitutive expression of the stress-response transcriptional coactivator multiprotein bridging factor 1c (MBF1c) in Arabidopsis (Arabidopsis thaliana) enhances the tolerance of transgenic plants to bacterial infection, heat, and osmotic stress. Moreover, the enhanced tolerance of transgenic plants to osmotic and heat stress was maintained even when these two stresses were combined. The expression of MBF1c in transgenic plants augmented the accumulation of a number of defense transcripts in response to heat stress. Transcriptome profiling and inhibitor studies suggest that MBF1c expression enhances the tolerance of transgenic plants to heat and osmotic stress by partially activating, or perturbing, the ethylene-response signal transduction pathway. Present findings suggest that MBF1 proteins could be used to enhance the tolerance of plants to different abiotic stresses.
Journal of biochemistry and molecular biology, 2006
To gain a better understanding on the function of the potato Solanum tuberosum Multiprotein Bridging Factor 1 protein (StMBF1) its interaction with the TATA box binding protein (TBP) was demonstrated. In addition we reported that StMBF1 rescues the yeast mbf1 mutant phenotype, indicating its role as a plant co-activator. These data reinforce the hypothesis that MBF1 function is also conserved among non closely related plant species. In addition, measurement of StMBF1 protein level by Western blot using anti-StMBF1 antibodies indicated that the protein level increased upon H(2)O(2) and heat shock treatments. However, the potato beta-1,3-glucanase protein level was not changed under the same experimental conditions. These data indicate that StMBF1 participates in the cell stress response against oxidative stress allowing us to suggest that MBF1 genes from different plant groups may share similar functions.
Transcriptional coactivator MBF1s from Arabidopsis predominantly localize in nucleolus
Journal of Plant Research, 2005
Multiprotein bridging factor 1 (MBF1) is a transcriptional coactivator. It has been reported that MBF1 changed its subcellular localization from cytoplasm into nuclei with a transcriptional activator for activation of a target gene expression in animals. We found that Arabidopsis MBF1s (AtMBF1s) predominantly localize in nucleolus. We previously reported that plant MBF1s were rapidly induced by several stresses, whereas animal MBF1s were not induced. Therefore, we suggest that MBF1-function in plants is controlled on the level of transcriptional induction but not by nuclear translocation, dissimilar from the case of MBF1s from animals.
Transcription Factors and Environmental Stresses in Plants
Emerging Technologies and Management of Crop Stress Tolerance, 2014
ABSTRACT The plants are exposed to environmental changes which are perceived as stresses when they are quick and extreme. Drought, salt and extreme temperatures, in particular, limit agricultural crops productivity, affecting all stages of plant growth and reproduction and therefore strongly decreasing crop yield. Worldwide estimates show that most yield loss (70%) can be directly due to abiotic stresses. Moreover the increasing phenomena of anthropization and the incorrect use of agricultural land have strongly contributed to land degradation. A large number of abiotic stress responsive genes have been reported in a variety of plants including Arabidopsis and the major crops such as barley, maize, rice and wheat. Transcriptional control of the expression of these genes is a crucial part of the plant response to abiotic stresses. Therefore in the last years the transcriptional mechanisms involved in the response to several abiotic stresses have been the subject of intense research, that have been productive in identifying transcription factors (TFs) as important 'key or master regulators' of gene expression under stress. An increasing number of TFs have been recently described and essential transcription factor binding regions have been identified for many genes. In fact, these systems of regulation work thanks to specific cis-elements located in the promoter regions of target genes, which are called regulons. The main regulons which respond to abiotic stresses are DREB1-CBF (dehydration-responsive element binding protein 1/C-repeat binding factor) which is involved in the cold stress response, DREB2 that acts in ABA-independent gene expression for response to heat and osmotic stress, whereas the ABA-responsive element (ABRE) binding protein (AREB)/ABRE binding factor (ABF) regulon operates in gene expression depending on ABA under osmotic stress. Other regulons, such as MYB/MYC and NAC regulons, induce or repress the expression of genes involved in abiotic stress-responsive. In the last few years, several studies have evidenced that TFs are powerful tools to engineer enhanced stress tolerance in plants. Therefore, in this chapter, we will summarize the major TFs involved in crop plants abiotic stress signalling and responses and the relative plants adaptive mechanisms at the molecular level. A major knowledge on molecular mechanisms that occur in stress condition are the one way pass for the improvement of stress tolerance in crop plants.