Polyamines such as spermidine and spermine are essential regulators of cell growth, differentiation, maintenance of ion balance and abiotic stress tolerance. Their levels are controlled by the spermidine/spermine N1 -acetyltransferase (SSAT) via acetylation to promote either their degradation or export outside the cell as shown in mammals. Plant genomes contain at least one gene coding for SSAT (also named NATA for N-AcetylTransferase Activity). Combining kinetics, HPLC-MS and crystallography, we show that three plant SSATs, one from the lower plant moss Physcomitrium patens and two from the higher plant Zea mays, acetylate various aliphatic polyamines and two amino acids lysine (Lys) and ornithine (Orn). Thus, plant SSATs exhibit a broad substrate specificity, unlike more specific human SSATs (hSSATs) as hSSAT1 targets polyamines, whereas hSSAT2 acetylates Lys and thiaLys. The crystal structures of two PpSSAT ternary complexes, one with Lys and CoA, the other with acetyl-CoA and polyethylene glycol (mimicking spermine), reveal a different binding mode for polyamine versus amino acid substrates accompanied by structural rearrangements of both the coenzyme and the enzyme. Two arginine residues, unique among plant SSATs, hold the carboxyl group of amino acid substrates. The most abundant acetylated compound accumulated in moss was N6 -acetyl-Lys, whereas N5 -acetyl-Orn, known to be toxic for aphids, was found in maize. Both plant species contain very low levels of acetylated polyamines. The present study provides a detailed biochemical and structural basis of plant SSAT enzymes that can acetylate a wide range of substrates and likely play various roles in planta.

• Klíčová slova
• Physcomitrium patens, Zea mays, N-acetyl transferase, X-ray crystallography, acetylation, coenzyme A, lysine, ornithine, polyamine, spermine,
• MeSH
• acetylace MeSH
• acetyltransferasy genetika   metabolismus   MeSH
• katalýza MeSH
• kukuřice setá metabolismus   MeSH
• lidé MeSH
• lysin metabolismus   MeSH
• ornithin metabolismus   MeSH
• polyaminy * metabolismus   MeSH
• savci metabolismus   MeSH
• spermidin * MeSH
• spermin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• acetyltransferasy MeSH
• lysin MeSH
• ornithin MeSH
• polyaminy * MeSH
• spermidin * MeSH
• spermin MeSH

The widespread occurrence of cyanobacteria blooms damages the water ecosystem and threatens the safety of potable water and human health. Exogenous L-lysine significantly inhibits the growth of a dominant cyanobacteria Microcystis aeruginosa in freshwater. However, the molecular mechanism of how lysine inhibits the growth of M. aeruginosa is unclear. In this study, both non-target and target metabolomic analysis were performed to investigate the effects of algicide L-lysine. The results showed that 8 mg L- 1 lysine most likely disrupts the metabolism of amino acids, especially the arginine and proline metabolism. According to targeted amino acid metabolomics analysis, only 3 amino acids (L-arginine, ornithine, and citrulline), which belong to the ornithine-ammonia cycle (OAC) in arginine metabolic pathway, showed elevated levels. The intracellular concentrations of ornithine, citrulline, and arginine increased by 115%, 124%, and 19.4%, respectively. These results indicate that L-lysine may affect arginine metabolism and OAC to inhibit the growth of M. aeruginosa.

• Klíčová slova
• Arginine metabolism, L-lysine, Metabolomic analysis, Microcystin, Microcystis aeruginosa, Ornithine-ammonia cycle,
• MeSH
• amoniak MeSH
• arginin chemie   metabolismus   MeSH
• citrulin metabolismus   MeSH
• ekosystém MeSH
• herbicidy * metabolismus   MeSH
• lidé MeSH
• lysin toxicita   metabolismus   MeSH
• Microcystis * metabolismus   MeSH
• mikrocystiny metabolismus   MeSH
• ornithin toxicita   metabolismus   MeSH
• sinice * metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• amoniak MeSH
• arginin MeSH
• citrulin MeSH
• herbicidy * MeSH
• lysin MeSH
• mikrocystiny MeSH
• ornithin MeSH

Leaf senescence can be induced by stress or aging, sometimes in a synergistic manner. It is generally acknowledged that the ability to withstand senescence-inducing conditions can provide plants with stress resilience. Although the signaling and transcriptional networks responsible for a delayed senescence phenotype, often referred to as a functional stay-green trait, have been actively investigated, very little is known about the subsequent metabolic adjustments conferring this aptitude to survival. First, using the individually darkened leaf (IDL) experimental setup, we compared IDLs of wild-type (WT) Arabidopsis (Arabidopsis thaliana) to several stay-green contexts, that is IDLs of two functional stay-green mutant lines, oresara1-2 (ore1-2) and an allele of phytochrome-interacting factor 5 (pif5), as well as to leaves from a WT plant entirely darkened (DP). We provide compelling evidence that arginine and ornithine, which accumulate in all stay-green contexts-likely due to the lack of induction of amino acids (AAs) transport-can delay the progression of senescence by fueling the Krebs cycle or the production of polyamines (PAs). Secondly, we show that the conversion of putrescine to spermidine (SPD) is controlled in an age-dependent manner. Thirdly, we demonstrate that SPD represses senescence via interference with ethylene signaling by stabilizing the ETHYLENE BINDING FACTOR1 and 2 (EBF1/2) complex. Taken together, our results identify arginine and ornithine as central metabolites influencing the stress- and age-dependent progression of leaf senescence. We propose that the regulatory loop between the pace of the AA export and the progression of leaf senescence provides the plant with a mechanism to fine-tune the induction of cell death in leaves, which, if triggered unnecessarily, can impede nutrient remobilization and thus plant growth and survival.

• MeSH
• Arabidopsis * metabolismus   MeSH
• arginin metabolismus   MeSH
• ethyleny metabolismus   MeSH
• listy rostlin metabolismus   MeSH
• ornithin genetika   metabolismus   MeSH
• proteiny huseníčku * metabolismus   MeSH
• regulace genové exprese u rostlin MeSH
• senescence rostlin MeSH
• transkripční faktory metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• arginin MeSH
• ethyleny MeSH
• ornithin MeSH
• proteiny huseníčku * MeSH
• transkripční faktory MeSH

INTRODUCTION: To date, there is not generally accepted and universal indicator of activity, and functional integrity of the small intestine in patients with coeliac disease. The aim of our study was to investigate whether serum concentrations of the non-essential amino acids citrulline and ornithine might have this function. METHODS: We examined serum citrulline and ornithine concentrations in a subgroup of patients with proven coeliac disease and healthy controls (blood donors). RESULTS: A total of 94 patients with coeliac disease (29 men, mean age 53 ± 18 years; 65 women, mean age 44 ± 14 years) and 35 healthy controls (blood donors) in whom coeliac disease was serologically excluded (10 men, mean age 51 ± 14 years; 25 women, mean age 46 ± 12 years) were included in the study. Significantly lower concentrations of serum ornithine were found in patients with coeliac disease (mean 65 ± 3 μmol/L; median 63 μmol/L, IQR 34 μmol/L, p < 0.001). No statistically nor clinically significant differences were found in the citrulline concentrations between the study and control group. CONCLUSIONS: Serum ornithine (but not citrulline) may be useful for assessing the functional status of the small intestine in uncomplicated coeliac disease. Further studies involving more detailed analysis of dietary and metabolic changes in patients will be needed to reach definitive conclusions.

• Klíčová slova
• citrulline, coeliac disease, ornithine,
• MeSH
• celiakie * MeSH
• citrulin * metabolismus   MeSH
• dieta MeSH
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• ornithin metabolismus   MeSH
• senioři MeSH
• Check Tag
• dospělí MeSH
• lidé středního věku MeSH
• lidé MeSH
• mužské pohlaví MeSH
• senioři MeSH
• ženské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• citrulin * MeSH
• ornithin MeSH

We adapted a radioligand receptor binding assay for measuring insulin levels in unknown samples. The assay enables rapid and accurate determination of insulin concentrations in experimental samples, such as from insulin-secreting cells. The principle of the method is based on the binding competition of insulin in a measured sample with a radiolabeled insulin for insulin receptor (IR) in IM-9 cells. Both key components, radiolabeled insulin and IM-9 cells, are commercially available. The IR binding assay was used to determine unknown amounts of insulin secreted by MIN6 β cell line after stimulation with glucose, arginine, ornithine, dopamine, and serotonin. The experimental data obtained by the IR binding assay were compared to the results determined by RIA kits and both methods showed a very good agreement of results. We observed the stimulation of glucose-induced insulin secretion from MIN6 cells by arginine, weaker stimulation by ornithine, but inhibitory effects of dopamine. Serotonin effects were either stimulatory or inhibitory, depending on the concentration of serotonin used. The results will require further investigation. The study also clearly revealed advantages of the IR binding assay that allows the measuring of a higher throughput of measured samples, with a broader range of concentrations than in the case of RIA kits. The IR binding assay can provide an alternative to standard RIA and ELISA assays for the determination of insulin levels in experimental samples and can be especially useful in scientific laboratories studying insulin production and secretion by β cells and searching for new modulators of insulin secretion.

• Klíčová slova
• Binding assay, Insulin receptor, Insulin secretion, Radioligand, Secretagogue, β Cells,
• MeSH
• arginin metabolismus   MeSH
• beta-buňky metabolismus   MeSH
• buněčné linie MeSH
• dopamin metabolismus   MeSH
• glukosa metabolismus   MeSH
• inzulin analýza   metabolismus   MeSH
• krysa rodu Rattus MeSH
• Langerhansovy ostrůvky metabolismus   MeSH
• lidé MeSH
• myši MeSH
• ornithin metabolismus   MeSH
• potkani Wistar MeSH
• radioimunoanalýza metody   MeSH
• radioligandová zkouška metody   MeSH
• sekrece inzulinu * MeSH
• serotonin metabolismus   MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• arginin MeSH
• dopamin MeSH
• glukosa MeSH
• inzulin MeSH
• ornithin MeSH
• serotonin MeSH

Eukaryotic complex phototrophs exhibit a colorful evolutionary history. At least three independent endosymbiotic events accompanied by the gene transfer from the endosymbiont to host assembled a complex genomic mosaic. Resulting patchwork may give rise to unique metabolic capabilities; on the other hand, it can also blur the reconstruction of phylogenetic relationships. The ornithine-urea cycle (OUC) belongs to the cornerstone of the metabolism of metazoans and, as found recently, also photosynthetic stramenopiles. We have analyzed the distribution and phylogenetic positions of genes encoding enzymes of the urea synthesis pathway in eukaryotes. We show here that metazoan and stramenopile OUC enzymes share common origins and that enzymes of the OUC found in primary algae (including plants) display different origins. The impact of this fact on the evolution of stramenopiles is discussed here.

• MeSH
• biologická evoluce MeSH
• databáze genetické MeSH
• fylogeneze MeSH
• Heterokontophyta metabolismus   MeSH
• močovina metabolismus   MeSH
• ornithin metabolismus   MeSH
• symbióza fyziologie   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• močovina MeSH
• ornithin MeSH

Glycation is a process closely related to the aging and pathogenesis of diabetic complications. Reactive alpha-dicarbonyl compounds (e.g., methylglyoxal) are formed during middle stage of glycation reaction. Compounds that would inhibit the glycation process have been seeked for years. The objective of this study was to investigate the inhibitory effect of hydroxycitric (0.25-2.5 mM) and uric acid (0.4-1.2 mM) on middle stage of protein glycation in vitro using the model containing aspartate aminotransferase (AST) and 0.5 mM methylglyoxal. Hydroxycitric acid, at all tested concentrations, reduced AST activity decrease and formation of fluorescent AGEs during incubation of the enzyme with methylglyoxal at 37 degrees C. This compound also prevented formation of high-molecular weight protein cross-links and changes in molecular charge of AST caused by glycation. Uric acid showed no positive anti-glycation activity. The results support the hypothesis that hydroxycitric acid has beneficial effects in controlling protein glycation.

• MeSH
• aspartátaminotransferasy chemie   metabolismus   MeSH
• citráty farmakologie   MeSH
• fluorescence MeSH
• glykosylace účinky léků   MeSH
• kvarterní struktura proteinů MeSH
• kyselina močová farmakologie   MeSH
• ornithin analogy a deriváty   metabolismus   MeSH
• produkty pokročilé glykace metabolismus   MeSH
• pyrimidiny metabolismus   MeSH
• pyruvaldehyd farmakologie   MeSH
• reagencia zkříženě vázaná farmakologie   MeSH
• Sus scrofa MeSH
• western blotting MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• argpyrimidine MeSH Prohlížeč
• aspartátaminotransferasy MeSH
• citráty MeSH
• hydroxycitric acid MeSH Prohlížeč
• kyselina močová MeSH
• ornithin MeSH
• produkty pokročilé glykace MeSH
• pyrimidiny MeSH
• pyruvaldehyd MeSH
• reagencia zkříženě vázaná MeSH

• MeSH
• acetylace MeSH
• biotransformace * MeSH
• glukuronáty metabolismus   MeSH
• glutamáty metabolismus   MeSH
• glykosidy metabolismus   MeSH
• léčivé přípravky metabolismus   MeSH
• lidé MeSH
• metylace MeSH
• ornithin metabolismus   MeSH
• sírany metabolismus   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• anglický abstrakt MeSH
• časopisecké články MeSH
• Názvy látek
• glukuronáty MeSH
• glutamáty MeSH
• glykosidy MeSH
• léčivé přípravky MeSH
• ornithin MeSH
• sírany MeSH

• MeSH
• aminobutyráty biosyntéza   MeSH
• arginin metabolismus   MeSH
• dekarboxylace MeSH
• denzitometrie MeSH
• elektroforéza na papíru MeSH
• Escherichia coli enzymologie   izolace a purifikace   metabolismus   MeSH
• feces mikrobiologie   MeSH
• glutamáty metabolismus   MeSH
• guanidiny biosyntéza   MeSH
• kadaverin biosyntéza   MeSH
• karboxylyasy metabolismus   MeSH
• kolorimetrie MeSH
• lidé MeSH
• lysin metabolismus   MeSH
• metody MeSH
• ornithin metabolismus   MeSH
• putrescin biosyntéza   MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• aminobutyráty MeSH
• arginin MeSH
• glutamáty MeSH
• guanidiny MeSH
• kadaverin MeSH
• karboxylyasy MeSH
• lysin MeSH
• ornithin MeSH
• putrescin MeSH