scholarly journals Polyamine biosynthesis in Xenopus laevis: the gene xlAZIN2/xlODC2 encodes a lysine decarboxylase

2019 ◽  
Author(s):  
Ana Lambertos ◽  
Rafael Peñafiel
Keyword(s):  
Model Organism ◽  
Lysine Decarboxylase ◽  
Polyamine Biosynthesis ◽  
Genomic Databases ◽  
Cellular Processes ◽  
Antizyme Inhibitor ◽  
Key Enzyme ◽  
Protein Resistant ◽  
Antizyme Inhibitors ◽  
Human And Mouse

AbstractOrnithine decarboxylase (ODC) is a key enzyme in the biosynthesis of polyamines, organic cations that are implicated in many cellular processes. The enzyme is regulated at the post-translational level by an unusual system that includes antizymes (AZs) and antizyme inhibitors (AZINs). Most studies on this complex regulatory mechanism have been focused on human and rodent cells, showing that AZINs (AZIN1 and AZIN2) are homologues of ODC but devoid of enzymatic activity. Little is known about Xenopus ODC and its paralogues, in spite of the relevance of Xenopus as a model organism for biomedical research. We have used the information existing in different genomic databases to compare the functional properties of the amphibian ODC1, AZIN1 and AZIN2/ODC2, by means of transient transfection experiments of HEK293T cells. Whereas the properties of xlODC1 and xlAZIN1 were similar to those reported for their mammalian orthologues, xlAZIN2/xlODC2 showed important differences with respect to human and mouse AZIN2. xlAZIN2 did not behave as an antizyme inhibitor, but it rather acts as an authentic decarboxylase forming cadaverine, due to its affinity for L-lysine as substrate; so, in accordance with this, it should be named as lysine decarboxylase (LDC). In addition, AZ1 stimulated the degradation of xlAZIN2 by the proteasome, but the removal of the 21 amino acid C-terminal tail, with a sequence quite different to that of mouse or human ODC, made the protein resistant to degradation. Collectively, our results indicate that in Xenopus there is only one antizyme inhibitor (xlAZIN1) and two decarboxylases, xlODC1 and xlLDC, with clear preferences for L-ornithine and L-lysine, respectively.

Regulation of cellular polyamine levels and cellular proliferation by antizyme and antizyme inhibitor

2009 ◽  
Vol 46 ◽  
pp. 47-62 ◽  
Author(s):  
Chaim Kahana
Keyword(s):  
Turnover Rate ◽  
Cellular Proliferation ◽  
Cellular Growth ◽  
26S Proteasome ◽  
Cellular Viability ◽  
Cellular Functions ◽  
Polyamine Biosynthesis ◽  
Cellular Processes ◽  
Antizyme Inhibitor ◽  
Key Enzyme

Polyamines are small aliphatic polycations present in all living cells. Polyamines are essential for cellular viability and are involved in regulating fundamental cellular processes, most notably cellular growth and proliferation. Being such central regulators of fundamental cellular functions, the intracellular polyamine concentration is tightly regulated at the levels of synthesis, uptake, excretion and catabolism. ODC (ornithine decarboxylase) is the first key enzyme in the polyamine biosynthesis pathway. ODC is characterized by an extremely rapid intracellular turnover rate, a trait that is central to the regulation of cellular polyamine homoeostasis. The degradation rate of ODC is regulated by its end-products, the polyamines, via a unique autoregulatory circuit. At the centre of this circuit is a small protein called Az (antizyme), whose synthesis is stimulated by polyamines. Az inactivates ODC and targets it to ubiquitin-independent degradation by the 26S proteasome. In addition, Az inhibits uptake of polyamines. Az itself is regulated by another ODC-related protein termed AzI (antizyme inhibitor). AzI is highly homologous with ODC, but it lacks ornithine-decarboxylating activity. Its ability to serve as a regulator is based on its high affinity to Az, which is greater than the affinity Az has to ODC. As a result, it interferes with the binding of Az to ODC, thus rescuing ODC from degradation and permitting uptake of polyamines.

scholarly journals Overexpression of arginine decarboxylase in transgenic plants

1997 ◽  
Vol 325 (2) ◽  
pp. 331-337 ◽  
Author(s):  
Daniel BURTIN ◽  
Anthony J. MICHAEL
Keyword(s):  
Transgenic Plants ◽  
Arginine Decarboxylase ◽  
Polyamine Metabolism ◽  
Morphological Development ◽  
Polyamine Biosynthesis ◽  
Adenosylmethionine Decarboxylase ◽  
Two Generations ◽  
Key Enzyme ◽  
Polyamine Conjugate ◽  
And Control

The activity of arginine decarboxylase (ADC), a key enzyme in plant polyamine biosynthesis, was manipulated in two generations of transgenic tobacco plants. Second-generation transgenic plants overexpressing an oat ADC cDNA contained high levels of oat ADC transcript relative to tobacco ADC, possessed elevated ADC enzyme activity and accumulated 10–20-fold more agmatine, the direct product of ADC. In the presence of high levels of the precursor agmatine, no increase in the levels of the polyamines putrescine, spermidine and spermine was detected in the transgenic plants. Similarly, the activities of ornithine decarboxylase and S-adenosylmethionine decarboxylase were unchanged. No diversion of polyamine metabolism into the hydroxycinnamic acid–polyamine conjugate pool or into the tobacco alkaloid nicotine was detected. Activity of the catabolic enzyme diamine oxidase was the same in transgenic and control plants. The elevated ADC activity and agmatine production were subjected to a metabolic/physical block preventing increased, i.e. deregulated, polyamine accumulation. Overaccumulation of agmatine in the transgenic plants did not affect morphological development.

scholarly journals Learning the distribution of single-cell chromosome conformations in bacteria reveals emergent order across genomic scales

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Joris J. B. Messelink ◽  
Muriel C. F. van Teeseling ◽  
Jacqueline Janssen ◽  
Martin Thanbichler ◽  
Chase P. Broedersz
Keyword(s):  
Single Cell ◽  
Caulobacter Crescentus ◽  
Model Organism ◽  
Super Resolution ◽  
Chromosome Organization ◽  
General Strategy ◽  
Cell Axis ◽  
Cellular Processes ◽  
Emergent Order ◽  
Genomic Clusters

AbstractThe order and variability of bacterial chromosome organization, contained within the distribution of chromosome conformations, are unclear. Here, we develop a fully data-driven maximum entropy approach to extract single-cell 3D chromosome conformations from Hi–C experiments on the model organism Caulobacter crescentus. The predictive power of our model is validated by independent experiments. We find that on large genomic scales, organizational features are predominantly present along the long cell axis: chromosomal loci exhibit striking long-ranged two-point axial correlations, indicating emergent order. This organization is associated with large genomic clusters we term Super Domains (SuDs), whose existence we support with super-resolution microscopy. On smaller genomic scales, our model reveals chromosome extensions that correlate with transcriptional and loop extrusion activity. Finally, we quantify the information contained in chromosome organization that may guide cellular processes. Our approach can be extended to other species, providing a general strategy to resolve variability in single-cell chromosomal organization.

scholarly journals Molecular Factors of Hypochlorite Tolerance in the Hypersaline Archaeon Haloferax volcanii

Genes ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 562 ◽  
Author(s):  
Miguel Gomez ◽  
Whinkie Leung ◽  
Swathi Dantuluri ◽  
Alexander Pillai ◽  
Zyan Gani ◽  
...  
Keyword(s):  
Hypochlorous Acid ◽  
Insertion Site ◽  
Model Organism ◽  
Halophilic Archaea ◽  
Haloferax Volcanii ◽  
Polyamine Biosynthesis ◽  
Active Compounds ◽  
Redox Active ◽  
High Concentrations ◽  
High Doses

Halophilic archaea thrive in hypersaline conditions associated with desiccation, ultraviolet (UV) irradiation and redox active compounds, and thus are naturally tolerant to a variety of stresses. Here, we identified mutations that promote enhanced tolerance of halophilic archaea to redox-active compounds using Haloferax volcanii as a model organism. The strains were isolated from a library of random transposon mutants for growth on high doses of sodium hypochlorite (NaOCl), an agent that forms hypochlorous acid (HOCl) and other redox acid compounds common to aqueous environments of high concentrations of chloride. The transposon insertion site in each of twenty isolated clones was mapped using the following: (i) inverse nested two-step PCR (INT-PCR) and (ii) semi-random two-step PCR (ST-PCR). Genes that were found to be disrupted in hypertolerant strains were associated with lysine deacetylation, proteasomes, transporters, polyamine biosynthesis, electron transfer, and other cellular processes. Further analysis revealed a ΔpsmA1 (α1) markerless deletion strain that produces only the α2 and β proteins of 20S proteasomes was hypertolerant to hypochlorite stress compared with wild type, which produces α1, α2, and β proteins. The results of this study provide new insights into archaeal tolerance of redox active compounds such as hypochlorite.

scholarly journals S-Nitrosoglutathione Reductase—The Master Regulator of Protein S-Nitrosation in Plant NO Signaling

Plants ◽  
2019 ◽  
Vol 8 (2) ◽  
pp. 48 ◽  
Author(s):  
Jana Jahnová ◽  
Lenka Luhová ◽  
Marek Petřivalský
Keyword(s):  
Stress Responses ◽  
Current Knowledge ◽  
Protein S ◽  
Defense Responses ◽  
Reactive Nitrogen ◽  
Cellular Processes ◽  
Protein Thiols ◽  
Key Enzyme ◽  
No Signaling ◽  
Cysteine Thiols

S-nitrosation has been recognized as an important mechanism of protein posttranslational regulations, based on the attachment of a nitroso group to cysteine thiols. Reversible S-nitrosation, similarly to other redox-base modifications of protein thiols, has a profound effect on protein structure and activity and is considered as a convergence of signaling pathways of reactive nitrogen and oxygen species. In plant, S-nitrosation is involved in a wide array of cellular processes during normal development and stress responses. This review summarizes current knowledge on S-nitrosoglutathione reductase (GSNOR), a key enzyme which regulates intracellular levels of S-nitrosoglutathione (GSNO) and indirectly also of protein S-nitrosothiols. GSNOR functions are mediated by its enzymatic activity, which catalyzes irreversible GSNO conversion to oxidized glutathione within the cellular catabolism of nitric oxide. GSNOR is involved in the maintenance of balanced levels of reactive nitrogen species and in the control of cellular redox state. Multiple functions of GSNOR in plant development via NO-dependent and -independent signaling mechanisms and in plant defense responses to abiotic and biotic stress conditions have been uncovered. Extensive studies of plants with down- and upregulated GSNOR, together with application of transcriptomics and proteomics approaches, seem promising for new insights into plant S-nitrosothiol metabolism and its regulation.

The Small GTPase Superfamily in Plants: A Conserved Regulatory Module with Novel Functions

2020 ◽  
Vol 71 (1) ◽  
pp. 247-272
Author(s):  
Erik Nielsen
Keyword(s):  
Membrane Trafficking ◽  
Binding Proteins ◽  
Model Organism ◽  
Nucleocytoplasmic Transport ◽  
Small Gtpase ◽  
Gtp Binding Proteins ◽  
Cellular Processes ◽  
Gtp Binding ◽  
Regulatory Module ◽  
Transport Vesicle

Small GTP-binding proteins represent a highly conserved signaling module in eukaryotes that regulates diverse cellular processes such as signal transduction, cytoskeletal organization and cell polarity, cell proliferation and differentiation, intracellular membrane trafficking and transport vesicle formation, and nucleocytoplasmic transport. These proteins function as molecular switches that cycle between active and inactive states, and this cycle is linked to GTP binding and hydrolysis. In this review, the roles of the plant complement of small GTP-binding proteins in these cellular processes are described, as well as accessory proteins that control their activity, and current understanding of the functions of individual members of these families in plants—with a focus on the model organism Arabidopsis—is presented. Some potential novel roles of these GTPases in plants, relative to their established roles in yeast and/or animal systems, are also discussed.

Seventy Years on from the Luria and Delbrûck Fluctuation Analysis: A Comparison of three Methods for Estimating Mutation Rate

2015 ◽  
Vol 6 ◽  
pp. 50-58
Author(s):  
I W Nyinoh
Keyword(s):  
Mutation Rate ◽  
Resistance Mutation ◽  
Model Organism ◽  
Relative Fitness ◽  
Mutation Rates ◽  
Fluctuation Analysis ◽  
Cellular Processes ◽  
Scientific Disciplines ◽  
Rate Fluctuation ◽  
Contemporary Interpretation

Seventy years ago, Luria and Delbrûck discovered fluctuation assay for estimating mutation rates. While this method is slightly dated, it is one of the few methods for estimating mutation rates in batch culture. Mutation rates when determined expose information on cellular processes and fundamental mutagenic mechanisms. Formerly, inferences drawn from fluctuation assay were sufficient to answer a specific question inbacterial genetics. However, contemporary interpretation of results goes far beyond the motive originally intended. As the fluctuation assay has gained popularity in various scientific disciplines, analyses of results obtained are not same. This study aims to compare the estimation of mutation rates using the Poison distribution (Po) method with, the Ma-Sarka Sandri maximum likelihood estimator and the Lea-Coulson median estimator. Mycobacterium smegmatismc 2 155was used as a model organism for Mycobacterium tuberculosis, and spontaneous mutations that arose in stationary phase cells exposed to antibiotic stress were investigated. Ten to twenty-four parallel cultures were tested with various anti-tuberculosis drugs; isoniazid, kanamycin, rifampicin and streptomycin. Minimum Inhibitory Concentration (MIC) of the drugs were also determinedto be; 8 ìg/mL, 0.24 ìg/mL, 16 ìg/mL and 0.5 ìg/mL for isoniazid, kanamycin, rifampicin and streptomycin respectively. The mutation rates obtained with the methods were very similar. To improve the power of deductions drawn from fluctuation assay, efforts should be made to experimentally determine the relative fitness of wild-type to mutant bacteria.This comparison is only a guide providing evidence regarding the authenticity of some of the methods currently available to researchers interested in estimating bacterial mutation rates.Keywords: antibiotic resistance, mutation rate, fluctuation assay, fluctuation analysis calculator.

PI-PLCbeta1 Expression in Patients with High-Risk Myelodysplastic Syndromes Is Affected by Azacitidine Treatment.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 2448-2448
Author(s):  
Carlo Finelli ◽  
Matilde Y. Follo ◽  
Costanza Bosi ◽  
Sara Mongiorgi ◽  
Cristina Clissa ◽  
...  
Keyword(s):  
High Risk ◽  
Myelodysplastic Syndromes ◽  
Erythroid Differentiation ◽  
Response To Treatment ◽  
Hl60 Cell ◽  
Pcr Analysis ◽  
Cellular Processes ◽  
Healthy Donors ◽  
Key Enzyme ◽  
Hl60 Cell Line

Abstract Phosphoinositide-specific phospholipase C (PI-PLC) beta1 is a key enzyme in nuclear signal transduction, and it is involved in many cellular processes, such as proliferation and differentiation (Manzoli L et al, Prog Lipid Res, 2005). In particular, the involvement of the PI-PLCbeta1 gene in erythroid differentiation lead us to investigate this gene in patients affected by high-risk Myelodysplastic Syndromes (MDS). It is still unclear what is the pathogenesis of the evolution of MDS into Acute Myeloid Leukemia (AML), even if the presence of a mono-allelic and cryptic deletion of the PI-PLCbeta1 gene, as well as an impaired regulation of the PI3K/Akt/mTOR axis, have been recently hypothesized to be implicated in mechanisms related to the disease progression (Lo Vasco VR et al, Leukemia, 2004;Follo MY et al, Cancer Res, 2007). In the present study, we performed a relative quantification, by Real-Time Polymerase Chain Reaction (PCR) analysis, on high-risk MDS patients, at baseline and during treatment with azacitidine. Furthermore, we evaluated the expression of the PI-PLCbeta1 gene on healthy donors and the HL60 cell line, which is useful for testing the accuracy of the technology because of its low expression of PI-PLCbeta1. To analyze and quantify the levels of the two different splicing variants of the PI-PLCbeta1 gene (a and b), we used a TaqMan isoform specific approach. We studied 8 patients with high-risk MDS (IPSS risk high or intermediate-II) treated with azaciditine, 5 of them showing a favourable response to treatment (1 patient: complete remission; 2 patients: partial remission; 2 patients: haematologic improvement). During the treatment with azacitidine, the non responsive patients (3/8) did not show any significant change in the levels of PI-PLCbeta1 mRNAs, whilst all the responders showed a marked increase of the PI-PLCbeta1 mRNA as compared with their baseline amount. Interestingly, the responsive patients showed fluctuations of PI-PLCbeta1 levels that could be related to their clinical status.Our data show a correlation between azacitidine treatment and PI-PLCbeta1 signalling in high-risk MDS, hinting at the likelihood that azacitidine could affect the transcriptional activity of PI-PLCbeta1, which is indeed a key player in the control of cell cycle.

scholarly journals The FlatwormMacrostomum lignanoIs a Powerful Model Organism for Ion Channel and Stem Cell Research

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Daniil Simanov ◽  
Imre Mellaart-Straver ◽  
Irina Sormacheva ◽  
Eugene Berezikov
Keyword(s):  
Stem Cell ◽  
Membrane Potential ◽  
Ion Channels ◽  
Cell Activity ◽  
Model Organism ◽  
Membrane Potentials ◽  
Stem Cell Maintenance ◽  
Cellular Processes ◽  
Proliferation And Differentiation ◽  
Voltage Gradients

Bioelectrical signals generated by ion channels play crucial roles in many cellular processes in both excitable and nonexcitable cells. Some ion channels are directly implemented in chemical signaling pathways, the others are involved in regulation of cytoplasmic or vesicular ion concentrations, pH, cell volume, and membrane potentials. Together with ion transporters and gap junction complexes, ion channels form steady-state voltage gradients across the cell membranes in nonexcitable cells. These membrane potentials are involved in regulation of such processes as migration guidance, cell proliferation, and body axis patterning during development and regeneration. While the importance of membrane potential in stem cell maintenance, proliferation, and differentiation is evident, the mechanisms of this bioelectric control of stem cell activity are still not well understood, and the role of specific ion channels in these processes remains unclear. Here we introduce the flatwormMacrostomum lignanoas a versatile model organism for addressing these topics. We discuss biological and experimental properties ofM. lignano, provide an overview of the recently developed experimental tools for this animal model, and demonstrate how manipulation of membrane potential influences regeneration inM. lignano.

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