RESUMO
BACKGROUND: The development of biomass crops aims to meet industrial yield demands, in order to optimize profitability and sustainability. Achieving these goals in an energy crop like sugarcane relies on breeding for sucrose accumulation, fiber content and stalk number. To expand the understanding of the biological pathways related to these traits, we evaluated gene expression of two groups of genotypes contrasting in biomass composition. RESULTS: First visible dewlap leaves were collected from 12 genotypes, six per group, to perform RNA-Seq. We found a high number of differentially expressed genes, showing how hybridization in a complex polyploid system caused extensive modifications in genome functioning. We found evidence that differences in transposition and defense related genes may arise due to the complex nature of the polyploid Saccharum genomes. Genotypes within both biomass groups showed substantial variability in genes involved in photosynthesis. However, most genes coding for photosystem components or those coding for phosphoenolpyruvate carboxylases (PEPCs) were upregulated in the high biomass group. Sucrose synthase (SuSy) coding genes were upregulated in the low biomass group, showing that this enzyme class can be involved with sucrose synthesis in leaves, similarly to sucrose phosphate synthase (SPS) and sucrose phosphate phosphatase (SPP). Genes in pathways related to biosynthesis of cell wall components and expansins coding genes showed low average expression levels and were mostly upregulated in the high biomass group. CONCLUSIONS: Together, these results show differences in carbohydrate synthesis and carbon partitioning in the source tissue of distinct phenotypic groups. Our data from sugarcane leaves revealed how hybridization in a complex polyploid system resulted in noticeably different transcriptomic profiles between contrasting genotypes.
Assuntos
Biomassa , Carbono/metabolismo , Genótipo , Saccharum/genética , Sacarose/metabolismo , Transcriptoma , Glucosiltransferases/genética , Glucosiltransferases/metabolismo , Fosfoenolpiruvato Carboxilase/genética , Fosfoenolpiruvato Carboxilase/metabolismo , Fotossíntese , Folhas de Planta/genética , Folhas de Planta/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Poliploidia , Saccharum/crescimento & desenvolvimento , Saccharum/metabolismo , Regulação para CimaRESUMO
Activation of phosphoenolpyruvate carboxylase (PEPC) enzymes by glucose 6-phosphate (G6P) and other phospho-sugars is of major physiological relevance. Previous kinetic, site-directed mutagenesis and crystallographic results are consistent with allosteric activation, but the existence of a G6P-allosteric site was questioned and competitive activation-in which G6P would bind to the active site eliciting the same positive homotropic effect as the substrate phosphoenolpyruvate (PEP)-was proposed. Here, we report the crystal structure of the PEPC-C4 isozyme from Zea mays with G6P well bound into the previously proposed allosteric site, unambiguously confirming its existence. To test its functionality, Asp239-which participates in a web of interactions of the protein with G6P-was changed to alanine. The D239A variant was not activated by G6P but, on the contrary, inhibited. Inhibition was also observed in the wild-type enzyme at concentrations of G6P higher than those producing activation, and probably arises from G6P binding to the active site in competition with PEP. The lower activity and cooperativity for the substrate PEP, lower activation by glycine and diminished response to malate of the D239A variant suggest that the heterotropic allosteric activation effects of free-PEP are also abolished in this variant. Together, our findings are consistent with both the existence of the G6P-allosteric site and its essentiality for the activation of PEPC enzymes by phosphorylated compounds. Furthermore, our findings suggest a central role of the G6P-allosteric site in the overall kinetics of these enzymes even in the absence of G6P or other phospho-sugars, because of its involvement in activation by free-PEP.
Assuntos
Glucose-6-Fosfato/química , Fosfoenolpiruvato Carboxilase/química , Fosfoenolpiruvato/química , Proteínas de Plantas/química , Zea mays/enzimologia , Regulação Alostérica , Domínio Catalítico , Glucose-6-Fosfato/metabolismo , Cinética , Fosfoenolpiruvato/metabolismo , Fosfoenolpiruvato Carboxilase/genética , Fosfoenolpiruvato Carboxilase/metabolismo , Proteínas de Plantas/genética , Proteínas de Plantas/metabolismo , Zea mays/genéticaRESUMO
Over-accumulation of triglycerides (TGs) in goose hepatocytes leads to the formation of fatty acid liver. Phosphoenolpyruvate carboxylase kinase 1 (PEPCK) is regarded as the rate-limiting enzyme for gluconeogenesis, and there is evidence that PEPCK is involved in regulating hepatic glucolipid metabolism. Hence, we proposed that PEPCK may have a role in goose hepatic steatosis. To test our hypothesis, the present study was conducted to firstly determine the sequence characteristics of goose PEPCK and then to explore its role in overfeeding-induced fatty liver. Our results showed that goose PEPCK encodes a 622-amino-acids protein that contains highly conserved oxaloacetate-binding domain, kinase-1 and kinase-2 motifs. PEPCK had higher mRNA levels in goose liver, and overfeeding markedly increased its expression in livers of both Sichuan White and Landes geese (p 0.05). Besides, expression of PEPCK was positively correlated with hepatic TG levels as well as plasma glucose and insulin concentrations. Additionally, in cultured goose primary hepatocyte, treatment with either oleic acid (0.8, 1.2 or 1.6 mM) or linoleic acid (0.125 or 0.25 mM) significantly (p 0.05) enhanced the expression of PEPCK. Taken together, these data suggested a role for PEPCK in the occurrence of overfeeding-induced goose hepatic steatosis.(AU)
Assuntos
Animais , Gansos/metabolismo , Gansos/fisiologia , Fosfoenolpiruvato Carboxilase/análise , Fosfoenolpiruvato Carboxilase/química , Fosfoenolpiruvato Carboxilase/genética , Fígado Gorduroso , HiperfagiaRESUMO
Over-accumulation of triglycerides (TGs) in goose hepatocytes leads to the formation of fatty acid liver. Phosphoenolpyruvate carboxylase kinase 1 (PEPCK) is regarded as the rate-limiting enzyme for gluconeogenesis, and there is evidence that PEPCK is involved in regulating hepatic glucolipid metabolism. Hence, we proposed that PEPCK may have a role in goose hepatic steatosis. To test our hypothesis, the present study was conducted to firstly determine the sequence characteristics of goose PEPCK and then to explore its role in overfeeding-induced fatty liver. Our results showed that goose PEPCK encodes a 622-amino-acids protein that contains highly conserved oxaloacetate-binding domain, kinase-1 and kinase-2 motifs. PEPCK had higher mRNA levels in goose liver, and overfeeding markedly increased its expression in livers of both Sichuan White and Landes geese (p 0.05). Besides, expression of PEPCK was positively correlated with hepatic TG levels as well as plasma glucose and insulin concentrations. Additionally, in cultured goose primary hepatocyte, treatment with either oleic acid (0.8, 1.2 or 1.6 mM) or linoleic acid (0.125 or 0.25 mM) significantly (p 0.05) enhanced the expression of PEPCK. Taken together, these data suggested a role for PEPCK in the occurrence of overfeeding-induced goose hepatic steatosis.
Assuntos
Animais , Fosfoenolpiruvato Carboxilase/análise , Fosfoenolpiruvato Carboxilase/genética , Fosfoenolpiruvato Carboxilase/química , Fígado Gorduroso , Gansos/fisiologia , Gansos/metabolismo , HiperfagiaRESUMO
The morphology and photosynthetic enzyme activity were studied in maize phosphoenolpyruvate carboxylase transgenic rice and non-transgenic rice. The results showed that compared with non-transgenic rice, phosphoenolpyruvate carboxylase transgenic rice was taller and had a stronger stalk, wider leaves, and more exuberant root system, with increased photosynthetic enzyme activity and improved yield components. Therefore, given the superiority of this plant type and heterosis, this is a novel breeding strategy for rice for the introduction of C4 photosynthesis genes into high-yielding rice.
Assuntos
Regulação Enzimológica da Expressão Gênica , Regulação da Expressão Gênica de Plantas , Oryza/fisiologia , Fenótipo , Fosfoenolpiruvato Carboxilase/genética , Fosfoenolpiruvato Carboxilase/metabolismo , Fotossíntese/genética , Folhas de Planta/genética , Folhas de Planta/metabolismo , Plantas Geneticamente ModificadasRESUMO
The objective of this study was to investigate the mRNA expression of hepatic phosphoenolpyruvate carboxykinase (PEPCK) after gastric bypass surgery (GBS) in rats with type 2 diabetic mellitus (T2DM). Thirty-six male Goto-Kakizaki rats, aged 12 weeks, were randomly divided into the GBS, sham operation with diet restriction (SO), and sham operation alone (control) groups (N = 12 per group). Liver specimens from all rats were obtained during the operation and 8 weeks after operation. Blood lipid levels were measured before and 8 weeks after operation. Fasting blood glucose (FBG), food intake, and body weight were recorded at weekly time points after operation. The blood glucose area under the curve (AUC) was calculated, and insulin sensitivity indices (ISI) were assessed. The expression PEPCK mRNA and protein were measured by real-time polymerase chain reaction and western blot. Compared with those of the SO and control groups, the blood lipid levels and the FBG in the GBS group was significantly decreased (P < 0.05), as was the AUC (P < 0.05), whereas the ISI was significantly increased (P < 0.05). PEPCK mRNA and protein levels in the GBS group were lower than those in the control group, whereas those in the SO group were significantly higher than those in controls (P < 0.05). In conclusion, GBS can reduce blood glucose in T2DM rats while improving glucose tolerance and hyperglycemia, and the mechanism appears to be associated with a decrease of hepatic PEPCK mRNA and protein expression.
Assuntos
Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Derivação Gástrica , Expressão Gênica , Fígado/metabolismo , Fosfoenolpiruvato Carboxilase/genética , Animais , Área Sob a Curva , Biomarcadores , Glicemia , Peso Corporal , Diabetes Mellitus Experimental , Modelos Animais de Doenças , Derivação Gástrica/métodos , Insulina/metabolismo , Resistência à Insulina , Lipídeos/sangue , Masculino , Fosfoenolpiruvato Carboxilase/metabolismo , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RatosRESUMO
Gluconeogenesis is an active pathway in Leishmania amastigotes and is essential for their survival within the mammalian cells. However, our knowledge about this pathway in trypanosomatids is very limited. We investigated the role of glycerol kinase (GK), phosphoenolpyruvate carboxykinase (PEPCK), and pyruvate phosphate dikinase (PPDK) in gluconeogenesis by generating the respective Leishmania mexicana Δgk, Δpepck, and Δppdk null mutants. Our results demonstrated that indeed GK, PEPCK, and PPDK are key players in the gluconeogenesis pathway in Leishmania, although stage-specific differences in their contribution to this pathway were found. GK participates in the entry of glycerol in promastigotes and amastigotes; PEPCK participates in the entry of aspartate in promastigotes, and PPDK is involved in the entry of alanine in amastigotes. Furthermore, the majority of alanine enters into the pathway via decarboxylation of pyruvate in promastigotes, whereas pathway redundancy is suggested for the entry of aspartate in amastigotes. Interestingly, we also found that l-lactate, an abundant glucogenic precursor in mammals, was used by Leishmania amastigotes to synthesize mannogen, entering the pathway through PPDK. On the basis of these new results, we propose a revision in the current model of gluconeogenesis in Leishmania, emphasizing the differences between amastigotes and promastigotes. This work underlines the importance of studying the trypanosomatid intracellular life cycle stages to gain a better understanding of the pathologies caused in humans.
Assuntos
Gluconeogênese , Glicerol Quinase/metabolismo , Leishmania mexicana/metabolismo , Fosfoenolpiruvato Carboxilase/metabolismo , Proteínas de Protozoários/metabolismo , Piruvato Ortofosfato Diquinase/metabolismo , Vias Biossintéticas/efeitos dos fármacos , Southern Blotting , Western Blotting , DNA de Protozoário/genética , Glucose/metabolismo , Glucose/farmacologia , Glicerol Quinase/genética , Humanos , Leishmania mexicana/genética , Leishmania mexicana/crescimento & desenvolvimento , Estágios do Ciclo de Vida , Mutação , Fosfoenolpiruvato Carboxilase/genética , Proteínas de Protozoários/genética , Piruvato Ortofosfato Diquinase/genéticaRESUMO
Phosphoenolpyruvate carboxykinase 1 (PCK1), also named PEPCK-C, is a multiple-function gene that is involved in gluconeogenesis, glyceroneogenesis, reproduction, female fertility, and development of obesity and diabetes. How its many functions are regulated was largely unknown. Therefore, we investigated mRNA expression and possible splice variants of PCK1 by screening cDNA in nine tissues from Holstein bulls and cows. PCK1 mRNA was highly expressed in the liver, kidney, ovary and testis; expression levels were low in the heart, spleen, and lung tissues. Expression of this gene was not detected in skeletal muscle. This led to the discovery of five novel bovine splice variants, named PCK1-AS1-PCK1-AS5. In PCK1-AS1, 51 nucleotides in the interior of exon 2 were spliced out. In PCK1-AS2, exons 2 and 3 were altered by the alternative 3' and 5' splice sites, respectively. PCK1-AS3 was truncated from the 3' end of exon 2 to the 5' end of exon 4. In PCK1-AS4, exon 5 was completely spliced out. In PCK1-AS5, exons 5 and 6 and the 5' end of exon 7 were spliced out. These splice variants (PCK1-AS1-PCK1-AS5) potentially encoded shorter proteins (605, 546, 373, 246 and 274 amino acids, respectively), when compared to the complete protein (622 amino acids). Considering the functional domains of the PCK1 protein, it is likely that these splice variants considerably affect the function of this protein; alternative splicing could be one of the mechanisms by which the diverse functions of PCK1 are regulated.
Assuntos
Bovinos/genética , Fosfoenolpiruvato Carboxilase/genética , Sequência de Aminoácidos , Animais , China , Clonagem Molecular , DNA Complementar , Éxons , Feminino , Masculino , Dados de Sequência Molecular , Músculo Esquelético/metabolismo , Fosfoenolpiruvato Carboxilase/metabolismo , Conformação Proteica , RNA/genética , Splicing de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Análise de Sequência de DNARESUMO
BACKGROUND: In Escherichia coli phosphoenolpyruvate (PEP) is a key central metabolism intermediate that participates in glucose transport, as precursor in several biosynthetic pathways and it is involved in allosteric regulation of glycolytic enzymes. In this work we generated W3110 derivative strains that lack the main PEP consumers PEP:sugar phosphotransferase system (PTS-) and pyruvate kinase isozymes PykA and PykF (PTS-pykA- and PTS-pykF-). To characterize the effects of these modifications on cell physiology, carbon flux distribution and aromatics production capacity were determined. RESULTS: When compared to reference strain W3110, strain VH33 (PTS-) displayed lower specific rates for growth, glucose consumption and acetate production as well as a higher biomass yield from glucose. These phenotypic effects were even more pronounced by the additional inactivation of PykA or PykF. Carbon flux analysis revealed that PTS inactivation causes a redirection of metabolic flux towards biomass formation. A cycle involving PEP carboxylase (Ppc) and PEP carboxykinase (Pck) was detected in all strains. In strains W3110, VH33 (PTS-) and VH35 (PTS-, pykF-), the net flux in this cycle was inversely correlated with the specific rate of glucose consumption and inactivation of Pck in these strains caused a reduction in growth rate. In the PTS- background, inactivation of PykA caused a reduction in Ppc and Pck cycling as well as a reduction in flux to TCA, whereas inactivation of PykF caused an increase in anaplerotic flux from PEP to OAA and an increased flux to TCA. The wild-type and mutant strains were modified to overproduce L-phenylalanine. In resting cells experiments, compared to reference strain, a 10, 4 and 7-fold higher aromatics yields from glucose were observed as consequence of PTS, PTS PykA and PTS PykF inactivation. CONCLUSIONS: Metabolic flux analysis performed on strains lacking the main activities generating pyruvate from PEP revealed the high degree of flexibility to perturbations of the central metabolic network in E. coli. The observed responses to reduced glucose uptake and PEP to pyruvate rate of conversion caused by PTS, PykA and PykF inactivation included flux rerouting in several central metabolism nodes towards anabolic biosynthetic reactions, thus compensating for carbon limitation in these mutant strains. The detected cycle involving Ppc and Pck was found to be required for maintaining the specific growth and glucose consumption rates in all studied strains. Strains VH33 (PTS-), VH34 (PTS-pykA-) and VH35 (PTS-pykF-) have useful properties for biotechnological processes, such as increased PEP availability and high biomass yields from glucose, making them useful for the production of aromatic compounds or recombinant proteins.
Assuntos
Escherichia coli/crescimento & desenvolvimento , Sistema Fosfotransferase de Açúcar do Fosfoenolpiruvato/metabolismo , Piruvato Quinase/metabolismo , Aminoácidos Aromáticos/metabolismo , Biomassa , Ciclo do Carbono , Escherichia coli/enzimologia , Escherichia coli/metabolismo , Isoenzimas/metabolismo , Mutação , Fosfoenolpiruvato Carboxiquinase (ATP)/genética , Fosfoenolpiruvato Carboxiquinase (ATP)/metabolismo , Fosfoenolpiruvato Carboxilase/genética , Fosfoenolpiruvato Carboxilase/metabolismoRESUMO
In bacteria, anaplerotic carbon fixation necessary for growth on carbon sources that are metabolized to three-carbon intermediates is provided by the activity of pyruvate carboxylase (PYC) and/or phosphoenolpyruvate carboxylase (PPC). In contrast to other rhizobia, which encode only one of these enzymes in their genomes, Bradyrhizobium japonicum USDA110 encodes both. Streptavidin-HRP western blot analysis of B. japonicum extracts demonstrated the presence of a biotin-containing protein whose molecular mass was indistinguishable from those of PYCs produced by Sinorhizobium meliloti and Rhizobium etli. Sequence analysis of the possible B. japonicum PYC revealed the lack of a pyruvate binding site as well as other characteristics indicating that the enzyme is non-functional, and PPC activity, but not PYC activity, was detectible in extracts prepared from strain USDA110. A B. japonicum cosmid genomic library was used to clone the ppc by functional complementation of S. meliloti pyc mutant RmF991. S. meliloti RmF991-carrying plasmids containing the B. japonicum ppc regained the ability to grow with glucose as a carbon source and produced PPC activity. The cloned ppc gene was inactivated by insertion mutagenesis and recombined into the USDA110 genome. The resulting ppc mutant was essentially devoid of PPC activity and grew poorly with glucose as carbon source in comparison to the wild-type strain. These data indicate that B. japonicum utilizes PPC, and not PYC, as an anaplerotic enzyme for growth on carbon sources metabolized to three-carbon intermediates.
Assuntos
Proteínas de Bactérias/metabolismo , Bradyrhizobium/enzimologia , Fosfoenolpiruvato Carboxilase/metabolismo , Proteínas de Bactérias/genética , Bradyrhizobium/genética , Carbono/metabolismo , Fosfoenolpiruvato Carboxilase/genética , Piruvato Carboxilase/genética , Piruvato Carboxilase/metabolismoRESUMO
The functional significance of tyrosine 207 of Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase was explored by examining the kinetic properties of the Tyr207Leu mutant. The variant enzyme retained the structural characteristics of the wild-type protein as indicated by circular dichroism, intrinsic fluorescence spectroscopy, and gel-exclusion chromatography. Kinetic analyses of the mutated variant showed a 15-fold increase in K(m)CO2, a 32-fold decrease in V(max), and a 6-fold decrease in K(m) for phosphoenolpyruvate. These results suggest that the hydroxyl group of Tyr 207 may polarize CO2 and oxaloacetate, thus facilitating the carboxylation/decarboxylation steps.
Assuntos
Mutação/genética , Fosfoenolpiruvato Carboxilase/genética , Saccharomyces cerevisiae/enzimologia , Tirosina/genética , Catálise , Cromatografia em Gel , Dicroísmo Circular , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Fosfoenolpiruvato Carboxilase/química , Espectrometria de Fluorescência , Tirosina/químicaRESUMO
The functional signifcance of tyrosine 207 of Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase was explored by examining the kinetic properties of the Tyr207Leu mutant. The variant enzyme retained the structural characteristics of the wild-type protein as indicated by circular dichroism, intrinsic fuorescence spectroscopy, and gel-exclusion chromatography. Kinetic analyses of the mutated variant showed a 15-fold increase in Km CO2, a 32fold decrease in Vmax, and a 6-fold decrease in Km for phosphoenolpyruvate. These results suggest that the hydroxyl group of Tyr 207 may polarize CO2 and oxaloacetate, thus facilitating the carboxylation/decarboxylation steps.
Assuntos
Mutação/genética , Fosfoenolpiruvato Carboxilase/genética , Saccharomyces cerevisiae/enzimologia , Tirosina/genética , Catálise , Cromatografia em Gel , Dicroísmo Circular , Regulação Enzimológica da Expressão Gênica , Regulação Fúngica da Expressão Gênica , Fosfoenolpiruvato Carboxilase/química , Espectrometria de Fluorescência , Tirosina/químicaRESUMO
Spatial and temporal regulation of phosphoenolpyruvate carboxylase (PEPC) is critical to the function of C(4) photosynthesis. The photosynthetic isoform of PEPC in the cytosol of mesophyll cells in Kranz-type C(4) photosynthesis has distinctive kinetic and regulatory properties. Some species in the Chenopodiaceae family perform C(4) photosynthesis without Kranz anatomy by spatial separation of initial fixation of atmospheric CO(2) via PEPC from C(4) acid decarboxylation and CO(2) donation to Rubisco within individual chlorenchyma cells. We studied molecular and functional features of PEPC in two single-cell functioning C(4) species (Bienertia sinuspersici, Suaeda aralocaspica) as compared to Kranz type (Haloxylon persicum, Salsola richteri, Suaeda eltonica) and C(3) (Suaeda linifolia) chenopods. It was found that PEPC from both types of C(4) chenopods displays higher specific activity than that of the C(3) species and shows kinetic and regulatory characteristics similar to those of C(4) species in other families in that they are subject to light/dark regulation by phosphorylation and display differential malate sensitivity. Also, the deduced amino acid sequence from leaf cDNA indicates that the single-cell functioning C(4) species possesses a Kranz-type C(4) isoform with a Ser in the amino terminal. A phylogeny of PEPC shows that isoforms in the two single-cell functioning C(4) species are in a clade with the C(3) and Kranz C(4) Suaeda spp. with high sequence homology. Overall, this study indicates that B. sinuspersici and S. aralocaspica have a C(4)-type PEPC similar to that in Kranz C(4) plants, which likely is required for effective function of C(4) photosynthesis.
Assuntos
Chenopodiaceae/enzimologia , Evolução Molecular , Fosfoenolpiruvato Carboxilase/metabolismo , Fotossíntese/fisiologia , Sequência de Aminoácidos , Chenopodiaceae/genética , Ritmo Circadiano , Ponto Isoelétrico , Cinética , Dados de Sequência Molecular , Fosfoenolpiruvato Carboxilase/química , Fosfoenolpiruvato Carboxilase/genética , Fosforilação , Especificidade da EspécieRESUMO
Proteoid roots play a major role in enabling white lupin (Lupinus albus L.) to adapt to phosphate (Pi) deficiency. Such roots release citrate from proteoid rootlets, which allows this species to mobilize Pi from sparingly soluble Pi sources. Release of citrate is preceded by a significant accumulation of organic acids, in which a Pi deficiency-inducible phosphoenolpyruvate carboxylase (PEPC) activity has been involved. To gain an insight into this adaptive mechanism, the expression of three different transcripts coding for PEPC was examined in proteoid rootlets of Pi-starved and Pi-starved-and-rescued white lupin. Semi-quantitative reverse transcriptase (RT)-PCR experiments performed with gene-specific primers targeted to the 3'-end region of the corresponding cDNAs revealed that the transcripts for these three PEPCs differentially accumulate in both Pi-starved and Pi-starved-and-rescued proteoid rootlets. Semi-quantitative RT-PCR analysis in Pi-starved proteoid rootlets sampled at different times after being rescued from Pi deficiency showed that Pi levels differentially down-regulated the three PEPC transcripts. RT-PCR experiments were further extended to Pi-starved and Pi-fed whole roots, cotyledons, and leaves on which a tissue-specific, Pi-dependent PEPC expression was observed. These results indicate that there exists at least three different transcripts coding for PEPC in proteoid root clusters of white lupin, whose expression are differentially regulated by Pi.
Assuntos
Regulação da Expressão Gênica de Plantas/fisiologia , Lupinus/enzimologia , Fosfatos/deficiência , Fosfoenolpiruvato Carboxilase/biossíntese , Raízes de Plantas/enzimologia , Sequência de Bases , Regulação Enzimológica da Expressão Gênica/fisiologia , Regulação da Expressão Gênica de Plantas/efeitos dos fármacos , Isoenzimas/biossíntese , Lupinus/genética , Dados de Sequência Molecular , Fosfoenolpiruvato Carboxilase/genética , RNA Mensageiro/metabolismo , Alinhamento de SequênciaRESUMO
To better understand the evolution of the enzyme phosphoenolpyruvate carboxylase (PEPC) and to test its versatility as a molecular character in phylogenetic and taxonomic studies, we have characterized and compared 70 new partial PEPC nucleotide and amino acid sequences (about 1100 bp of the 3' side of the gene) from 50 plant species (24 species of Bryophyta, 1 of Pteridophyta, and 25 of Spermatophyta). Together with previously published data, the new set of sequences allowed us to construct the up to now most complete phylogenetic tree of PEPC, where the PEPC sequences cluster according to both the taxonomic positions of the donor plants and the assumed specific function of the PEPC isoforms. Altogether, the study further strengthens the view that PEPC sequences can provide interesting information for the reconstruction of phylogenetic relations between organisms and metabolic pathways. To avoid confusion in future discussion, we propose a new nomenclature for the denotation of PEPC isoforms.