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Query: EC:3.2.1.26 (invertase)
 4,927 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

An attempt was made to determine whether sporulation and inducible enzyme synthesis in Bacillus subtilis are controlled by the same mechanism of catabolite repression. By the use of a thymine-requiring strain, it has been shown that, whereas sporulation remained repressed unless chromosome replication proceeded to completion, the induction of the enzymes histidase, sucrase, and alpha-glucosidase proceeded quite normally in the absence of continued deoxyribonucleic acid synthesis. It is concluded that the mechanism for overcoming the repression of sporulation differs qualitatively from that involved in overcoming the repression of inducible enzyme synthesis. Attempts to isolate pleiotropic mutants that would provide additional support for this contention were unsuccessful. A pleiotropic mutant deficient in phosphoenolpyruvate-dependent phosphotransferase activity sporulated quite well, whereas a mutant presumed deficient in glutamate synthetase sporulated poorly under all conditions.
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PMID:Comparative studies on induction of sporulation and synthesis of inducible enzymes in Bacillus subtilis. 421 91

Sucrose synthase (SS) activity has been suggested to be a key point of regulation in nodule metabolism since this enzyme is down-regulated in response to different stresses which lead to decreased nitrogen fixation. In soybean, a dramatic decline of SS transcripts has been observed within 1 d from the onset of drought. Such a quick response suggests mediation by a signal transduction molecule. Abscisic acid (ABA) is a likely candidate to act as such a molecule as it mediates in a significant number of plant responses to environmental constraints. The hypothesis of ABA controlling nodule metabolism was approached in this work by assessing nodule responses to exogenous ABA supply in pea. Under the experimental conditions, ABA did not affect plant biomass, nodule numbers or dry weight. However, nitrogen fixation rate was reduced by 70% within 5 d and by 80% after 9 d leading to a reduced plant organic nitrogen content. Leghaemoglobin (Lb) content declined in parallel with that of nitrogen fixation. SS activity, however, was not affected by ABA treatment, and neither were the activities of the enzymes aspartate amino transferase, alkaline invertase, malate dehydrogenase, glutamate synthase, uridine diphosphoglucose pyrophosphorylase, isocitrate dehydrogenase, and glutamine synthetase. Nodule bacteroid-soluble protein content was reduced in nodules only after 9 d of ABA treatment. These results do not support the hypothesis that ABA directly regulates SS activity. However, they do suggest the occurrence of at least two different control pathways in nodules under environmental constraints, which include ABA being involved in a Lb/oxygen-related control of nitrogen fixation.
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PMID:Abscisic acid induces a decline in nitrogen fixation that involves leghaemoglobin, but is independent of sucrose synthase activity. 1128 73

We performed comparative metabolome and transcriptome analyses throughout fruit development using the tomato cultivar M82 and its near-isogenic line IL8-3, with interesting and useful traits such as a high content of soluble solids. Marked differences between M82 and IL8-3 were found not only in ripe fruits but also at 20 days after flowering (DAF) in the hierarchical clustering analysis of the metabolome, whereas patterns were similar between the two genotypes at 10 and 30 DAF. Our metabolome analysis conclusively showed that 20 DAF is an important stage of fruit metabolism and that the Solanum pennellii introgressed region in IL8-3 plays a key role in metabolic changes at this stage. Carbohydrate and amino acid metabolism were found to be promoted in IL8-3 at 20 DAF and the ripening stage, respectively, whereas transcriptome analysis showed no marked differences between the two genotypes, indicating that dynamic metabolic regulation at 20 DAF and the ripening stage was controlled by relatively few genes. The transcript levels of the cell wall invertase (LIN6) and sucrose synthase (TOMSSF) genes in starch and sucrose metabolic pathway and that of the glutamate synthase (SlGOGAT) gene in the amino acid metabolic pathway in IL8-3 fruit were higher than those in M82, and SlGOGAT expression was enhanced under high-sugar conditions. The results suggest that the promotion of carbohydrate metabolism by LIN6 and TOMSSF in IL8-3 fruit at 20 DAF affects SlGOGAT expression and amino acid accumulation via higher sugar concentration at the late stage of fruit development.
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PMID:Dynamic Metabolic Regulation by a Chromosome Segment from a Wild Relative During Fruit Development in a Tomato Introgression Line, IL8-3. 2707 98

To mitigate the deleterious effects of abiotic stress, the use of plant growth-promoting bacteria along with diazotrophic bacteria has been increasing. The objectives of this study were to investigate the key enzymes related to nitrogen and carbon metabolism in the biological nitrogen fixation process and to elucidate the activities of these enzymes by the synergistic interaction between Bradyrhizobium and plant growth-promoting bacteria in the absence and presence of salt stress. Cowpea plants were cultivated under axenic conditions, inoculated with Bradyrhizobium and co-inoculated with Bradyrhizobium sp. and Actinomadura sp., Bradyrhizobium sp. and Bacillus sp., Bradyrhizobium sp. and Paenibacillus graminis, and Bradyrhizobium sp. and Streptomycessp.; the plants were also maintained in the absence (control) and presence of salt stress (50mmolL-1 NaCl). Salinity reduced the amino acids, free ammonia, ureides, proteins and total nitrogen content in nodules and increased the levels of sucrose and soluble sugars. The co-inoculations responded differently to the activity of glutamine synthetase enzymes under salt stress, as well as glutamate synthase, glutamate dehydrogenase aminating, and acid invertase in the control and salt stress. Considering the development conditions of this experiment, co-inoculation with Bradyrhizobium sp. and Bacillus sp. in cowpea provided better symbiotic performance, mitigating the deleterious effects of salt stress.
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PMID:Changes induced by co-inoculation in nitrogen-carbon metabolism in cowpea under salinity stress. 2970 26

The use of mixed nitrate and ammonium as a nitrogen source can improve plant growth. Here, we used metabolomics and transcriptomics to study the underlying mechanisms. Maize plants were grown hydroponically in the presence of three forms of nitrogen (nitrate alone, 75%/25% nitrate/ammonium, and ammonium alone). Plants grown with mixed nitrogen had a higher photosynthetic rate than those supplied only with nitrate, and had the highest leaf area and shoot and root biomass among the three nitrogen treatments. In shoot and root, the concentration of nitrogenous compounds (ammonium, glutamine, and asparagine) and carbohydrates (sucrose, glucose, and fructose) in plants with a mixed nitrogen supply was higher than that with nitrate supply, but lower than that with ammonium supply. The activity of the related enzymes (glutamate synthase, asparagine synthase, phosphoenolpyruvate carboxylase, invertase, and ADP-glucose pyrophosphorylase) changed accordingly. Specifically, the mixed nitrogen source enhanced auxin synthesis via the shikimic acid pathway, as indicated by the higher levels of phosphoenolpyruvate and tryptophan compared with the other two treatments. The expression of corresponding genes involving auxin synthesis and response was up-regulated. Supply of only ammonium resulted in high levels of glutamine and asparagine, starch, and trehalose hexaphosphate. We conclude that, in addition to increased photosynthesis, mixed nitrogen supply enhances leaf growth via increasing auxin synthesis to build a large sink for carbon and nitrogen utilization, which, in turn, facilitates further carbon assimilation and nitrogen uptake.
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PMID:Increased biomass accumulation in maize grown in mixed nitrogen supply is mediated by auxin synthesis. 3075 46