scholarly journals Distinct Peculiarities of In Planta Synthesis of Isoprenoid and Aromatic Cytokinins

Biomolecules ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 86
Author(s):  
Vladimir Oslovsky ◽  
Ekaterina Savelieva ◽  
Mikhail Drenichev ◽  
Georgy Romanov ◽  
Sergey Mikhailov
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Cells ◽  
Cytokinin Activity ◽  
Hormonal Activity ◽  
In Planta ◽  
Significant Difference ◽  
Aromatic Cytokinins ◽  
Derivatives Of ◽  
Ribose Moiety

The biosynthesis of aromatic cytokinins in planta, unlike isoprenoid cytokinins, is still unknown. To compare the final steps of biosynthesis pathways of aromatic and isoprenoid cytokinins, we synthesized a series of nucleoside derivatives of natural cytokinins starting from acyl-protected ribofuranosyl-, 2′-deoxyribofuranosyl- and 5′-deoxyribofuranosyladenine derivatives using stereoselective alkylation with further deblocking. Their cytokinin activity was determined in two bioassays based on model plants Arabidopsis thaliana and Amaranthus caudatus. Unlike active cytokinins-bases, cytokinin nucleosides lack the hormonal activity until the ribose moiety is removed. According to our experiments, ribo-, 2′-deoxyribo- and 5′-deoxyribo-derivatives of isoprenoid cytokinin N6-isopentenyladenine turned in planta into active cytokinins with clear hormonal activity. As for aromatic cytokinins, both 2′-deoxyribo- and 5′-deoxyribo-derivatives did not exhibit analogous activity in Arabidopsis. The 5′-deoxyribo-derivatives cannot be phosphorylated enzymatically in vivo; therefore, they cannot be “activated” by the direct LOG-mediated cleavage, largely occurring with cytokinin ribonucleotides in plant cells. The contrasting effects exerted by deoxyribonucleosides of isoprenoid (true hormonal activity) and aromatic (almost no activity) cytokinins indicates a significant difference in the biosynthesis of these compounds.

scholarly journals Comparative analysis of the biosynthesis of isoprenoid and aromatic cytokinins

2019 ◽  
Vol 488 (6) ◽  
pp. 673-676
Author(s):  
V. E. Oslovsky ◽  
E. M. Savelieva ◽  
M. S. Drenichev ◽  
G. A. Romanov ◽  
S. N. Mikhailov
Keyword(s):  
Test System ◽  
Cytokinin Activity ◽  
In Planta ◽  
Similar Activity ◽  
Model Plant Arabidopsis Thaliana ◽  
Aromatic Cytokinins ◽  
Derivatives Of ◽  
Ribose Moiety ◽  
Plant Arabidopsis Thaliana

To compare the biosynthesis pathways of aromatic and isoprenoid cytokinins, a series of nucleoside derivatives of natural cytokinins was synthesized and their cytokinin activity was determined in a test system based on the model plant Arabidopsis thaliana. Cytokinin nucleosides are known to lack the hormonal activity until cleaving the ribose moiety at the position 9. Our experiments have shown that both ribo- and 5-deoxyribo derivatives of N 6-isopentenyladenine were able to turn into active cytokinins in planta exhibiting cytokinin activity. By contrast, 5-deoxy nucleosides of aromatic cytokinins did not show similar activity. Since 5-deoxy nucleosides cannot phosphorylate in vivo, the direct pathway of active cytokinin formation by cleavage of nucleotides is blocked here. The detected activity in 5-deoxy nucleosides of isoprenoid cytokinins and the lack of the activity in 5-deoxy nucleosides of aromatic cytokinins indicates a difference in the biosynthesis of these compounds.

scholarly journals In vivo efficacies of 5'-methylthioadenosine analogs as trypanocides.

1997 ◽  
Vol 41 (10) ◽  
pp. 2108-2112 ◽  
Author(s):  
C J Bacchi ◽  
K Sanabria ◽  
A J Spiess ◽  
M Vargas ◽  
C J Marasco ◽  
...  
Keyword(s):  
Trypanosoma Brucei ◽  
East African ◽  
Trypanosoma Brucei Rhodesiense ◽  
Polyamine Biosynthesis ◽  
Substrate Analogs ◽  
Osmotic Pumps ◽  
Derivatives Of ◽  
Ribose Moiety

5'-Deoxy-5'-(methylthio)adenosine (MTA), a key by-product of polyamine biosynthesis, is cleaved by MTA phosphorylase and is salvaged as adenine and, through conversion of the ribose moiety, methionine. An analog of MTA, 5'-deoxy-5'-(hydroxyethylthio)adenosine (HETA), is a substrate for trypanosome MTA phosphorylase and is active in vitro and in vivo against Trypanosoma brucei brucei, an agent of bovine trypanosomiasis. In this study, HETA and three O-acylated HETA derivatives were examined for their activities against model infections of T. b. brucei and Trypanosoma brucei rhodesiense, the agent of East African sleeping sickness. HETA was curative (>60%) for infections caused by 5 of 11 clinical isolates of T. b. rhodesiense when it was given to mice at 200 mg/kg of body weight for 7 days as a continuous infusion in osmotic pumps. HETA at 150 to 200 mg/kg also extended the life spans of the mice infected with four additional isolates two- to fivefold. Di- and tri-O-acetylated derivatives of HETA also proved curative for the infections, while a tri-O-propionyl derivative, although also curative, was not as effective. This study indicates that substrate analogs of MTA should be given important consideration for development as novel chemotherapies against African trypanosomiasis.

Conservation of targeting but divergence in function and quality control of peroxisomal ABC transporters: an analysis using cross-kingdom expression

2011 ◽  
Vol 436 (3) ◽  
pp. 547-557 ◽  
Author(s):  
Xuebin Zhang ◽  
Carine De Marcos Lousa ◽  
Nellie Schutte-Lensink ◽  
Rob Ofman ◽  
Ronald J. Wanders ◽  
...  
Keyword(s):  
Quality Control ◽  
Arabidopsis Thaliana ◽  
Abc Transporters ◽  
Plant Cells ◽  
Related Protein ◽  
Peroxisomal Membrane ◽  
And Function ◽  
Native Host

ABC (ATP-binding cassette) subfamily D transporters are found in all eukaryotic kingdoms and are known to play essential roles in mammals and plants; however, their number, organization and physiological contexts differ. Via cross-kingdom expression experiments, we have explored the conservation of targeting, protein stability and function between mammalian and plant ABCD transporters. When expressed in tobacco epidermal cells, the mammalian ABCD proteins ALDP (adrenoleukodystrophy protein), ALDR (adrenoleukodystrophy-related protein) and PMP70 (70 kDa peroxisomal membrane protein) targeted faithfully to peroxisomes and P70R (PMP70-related protein) targeted to the ER (endoplasmic reticulum), as in the native host. The Arabidopsis thaliana peroxin AtPex19_1 interacted with human peroxisomal ABC transporters both in vivo and in vitro, providing an explanation for the fidelity of targeting. The fate of X-linked adrenoleukodystrophy disease-related mutants differed between fibroblasts and plant cells. In fibroblasts, levels of ALDP in some ‘protein-absent’ mutants were increased by low-temperature culture, in some cases restoring function. In contrast, all mutant ALDP proteins examined were stable and correctly targeted in plant cells, regardless of their fate in fibroblasts. ALDR complemented the seed germination defect of the Arabidopsis cts-1 mutant which lacks the peroxisomal ABCD transporter CTS (Comatose), but neither ALDR nor ALDP was able to rescue the defect in fatty acid β-oxidation in establishing seedlings. Taken together, our results indicate that the mechanism for trafficking of peroxisomal membrane proteins is shared between plants and mammals, but suggest differences in the sensing and turnover of mutant ABC transporter proteins and differences in substrate specificity and/or function.

In vivo phosphorylation of FtsZ2 in Arabidopsis thaliana

2012 ◽  
Vol 446 (3) ◽  
pp. 517-521 ◽  
Author(s):  
Daniela Gargano ◽  
Jodi Maple-Grødem ◽  
Simon G. Møller
Keyword(s):  
Arabidopsis Thaliana ◽  
Phosphoglycerate Kinase ◽  
Gtpase Activity ◽  
Plastid Division ◽  
In Planta ◽  
Ftsz Protein ◽  
Proteomics Approach

The tubulin-like FtsZ protein initiates assembly of the bacterial and plastid division machineries. In bacteria, phosphorylation of FtsZ impairs GTPase activity, polymerization and interactions with other division proteins. Using a proteomics approach, we have shown that AtFtsZ2 is phosphorylated in vivo in Arabidopsis and that PGK1 (phosphoglycerate kinase 1) interacts with AtFtsZ2 in planta, suggesting a possible role in FtsZ phosphorylation.

scholarly journals Cortical tension overrides geometrical cues to orient microtubules in confined protoplasts

2020 ◽  
Vol 117 (51) ◽  
pp. 32731-32738
Author(s):  
Leia Colin ◽  
Antoine Chevallier ◽  
Satoru Tsugawa ◽  
Florian Gacon ◽  
Christophe Godin ◽  
...  
Keyword(s):  
Plant Cells ◽  
Cell System ◽  
Cellulose Synthesis ◽  
Cortical Microtubules ◽  
In Planta ◽  
Curvature Ratio ◽  
Cortical Tension ◽  
Maximal Tension

In plant cells, cortical microtubules (CMTs) generally control morphogenesis by guiding cellulose synthesis. CMT alignment has been proposed to depend on geometrical cues, with microtubules aligning with the cell long axis in silico and in vitro. Yet, CMTs are usually transverse in vivo, i.e., along predicted maximal tension, which is transverse for cylindrical pressurized vessels. Here, we adapted a microwell setup to test these predictions in a single-cell system. We confined protoplasts laterally to impose a curvature ratio and modulated pressurization through osmotic changes. We find that CMTs can be longitudinal or transverse in wallless protoplasts and that the switch in CMT orientation depends on pressurization. In particular, longitudinal CMTs become transverse when cortical tension increases. This explains the dual behavior of CMTs in planta: CMTs become longitudinal when stress levels become low, while stable transverse CMT alignments in tissues result from their autonomous response to tensile stress fluctuations.

scholarly journals Differences in the Manifestation of Cell Pluripotence In Vivo and In Vitro in the Mutant Arabidopsis thaliana with the Phenotype of Cell Memory Disorder

2021 ◽  
Vol 68 (1) ◽  
pp. 46-55
Author(s):  
E. V. Kupriyanova ◽  
E. R. Denisova ◽  
M. A. Baier ◽  
T. A. Ezhova
Keyword(s):  
Arabidopsis Thaliana ◽  
Shoot Regeneration ◽  
Cultured Cells ◽  
De Novo ◽  
Epigenetic Memory ◽  
In Planta ◽  
Pluripotency Genes

Abstract Plant cells cultivated in vitro are a convenient model for studying the genetic and physiological mechanisms necessary for the cells to acquire a state of pluripotency. Earlier studies on a model plant Arabidopsis thaliana (L.) Heynh. have identified the key role of genes that determine the pluripotency of cells in the shoot apical meristem in de novo shoot regeneration in tissue culture. In accordance with this, cells of mutant plants with a higher level of expression of pluripotency genes were characterized by an increased potential for de novo shoot regeneration. The tae mutant was the exception to this rule. The mutant resumed the expression of pluripotency genes and cell proliferation at the late stages of leaf development, which indicates a violation of the mechanisms for maintaining epigenetic cellular memory. At the same time, leaf cells cultured in vitro showed a lower proliferative activity compared to the wild type and were not capable of de novo regeneration of shoots. A decrease in the regenerative potential of cultured cells of the tae mutant indicates an important role of epigenetic memory in the response of cells to exogenous hormones. Impaired epigenetic memory of leaf cells of the tae mutant and differences in their proliferative and regenerative capacities in planta and in vitro make this mutant a unique model for studying the role of epigenetic modifications in the regulation of cell pluripotency.

scholarly journals Reappraisal of Spinach-based RNA Visualization in Plants

2020 ◽  
Author(s):  
Zhiming Yu ◽  
Fengling Mei ◽  
Haiting Yan ◽  
Qiyuan Chen ◽  
Mengqin Yao ◽  
...  
Keyword(s):  
Tandem Repeats ◽  
Rna Binding ◽  
Ex Vivo ◽  
Plant Cells ◽  
Quantitative Detection ◽  
Rna Aptamer ◽  
In Planta ◽  
Green Fluorescence

ABSTRACTRNAs can be imaged in living cells using molecular beacons, RNA-binding labeled proteins and RNA aptamer-based approaches. However, Spinach RNA-mimicking GFP (RMG) has not been successfully used to monitor cellular RNAs in plants. In this study, we re-evaluated Spinach-based RNA visualization in different plants via transient, transgenic, and virus-based expression strategies. We found that like bacterial, yeast and human cellular tRNAs, plant tRNAs such as tRNALys (K) can protect and/or stabilize the spinach RNA aptamer interaction with the fluorophore DFHBI enabling detectable levels of green fluorescence to be emitted. The tRNALys-spinach-tRNALys (KSK), once delivered into “chloroplast-free” onion epidermal cells can emit strong green fluorescence in the presence of DFHBI. Transgenic or virus-based expression of monomer KSK, in either stably transformed or virus-infected Nicotinana benthamiana plants, failed to show RMG fluorescence. However, incorporating tandem repeats of KSK into recombinant viral RNAs, enabled qualitative and quantitative detection, both in vitro and ex vivo (ex planta), of KSK-specific green fluorescence, though RMG was less obvious in vivo (in planta). These findings demonstrate Spinach-based RNA visualization has the potential for ex vivo and in vivo monitoring RNAs in plant cells.One sentence summarySpinach-based RMG technology was reevaluated to have potential for ex vivo and in vivo monitoring RNAs in plant cells.

scholarly journals EFR-Mediated Innate Immune Response in Arabidopsis thaliana is a Useful Tool for Identification of Novel ERQC Modulators

Genes ◽  
2018 ◽  
Vol 10 (1) ◽  
pp. 15
Author(s):  
Andrea Lia ◽  
Antonia Gallo ◽  
Lucia Marti ◽  
Pietro Roversi ◽  
Angelo Santino
Keyword(s):  
Immune Response ◽  
Arabidopsis Thaliana ◽  
Innate Immune Response ◽  
Residual Activity ◽  
Innate Immune ◽  
In Planta ◽  
Plant Weight ◽  
Mutant Seedling

Plants offer a simpler and cheaper alternative to mammalian animal models for the study of endoplasmic reticulum glycoprotein folding quality control (ERQC). In particular, the Arabidopsis thaliana (At) innate immune response to bacterial peptides provides an easy means of assaying ERQC function in vivo. A number of mutants that are useful to study ERQC in planta have been described in the literature, but only for a subset of these mutants the innate immune response to bacterial elicitors has been measured beyond monitoring plant weight and some physio-pathological parameters related to the plant immune response. In order to probe deeper into the role of ERQC in the plant immune response, we monitored expression levels of the Phosphate-induced 1 (PHI-1) and reticulin-oxidase homologue (RET-OX) genes in the At ER α-Glu II rsw3 and the At UGGT uggt1-1 mutant plants, in response to bacterial peptides elf18 and flg22. The elf18 response was impaired in the rsw3 but not completely abrogated in the uggt1-1 mutant plants, raising the possibility that the latter enzyme is partly dispensable for EF-Tu receptor (EFR) signaling. In the rsw3 mutant, seedling growth was impaired only by concomitant application of the At ER α-Glu II NB-DNJ inhibitor at concentrations above 500 nM, compatibly with residual activity in this mutant. The study highlights the need for extending plant innate immune response studies to assays sampling EFR signaling at the molecular level.

scholarly journals In Planta Preliminary Screening of ER Glycoprotein Folding Quality Control (ERQC) Modulators

2018 ◽  
Vol 19 (7) ◽  
pp. 2135 ◽  
Author(s):  
Lucia Marti ◽  
Andrea Lia ◽  
Ida-Barbara Reca ◽  
Pietro Roversi ◽  
Angelo Santino ◽  
...  
Keyword(s):  
Immune Response ◽  
Quality Control ◽  
Arabidopsis Thaliana ◽  
Low Cost ◽  
Proof Of Concept ◽  
Development Programs ◽  
In Planta ◽  
Treated Plant ◽  
Small Molecule Modulators

Small molecule modulators of the Endoplasmic Reticulum glycoprotein folding quality control (ERQC) machinery have broad-spectrum antiviral activity against a number of enveloped viruses and have the potential to rescue secretion of misfolded but active glycoproteins in rare diseases. In vivo assays of candidate inhibitors in mammals are expensive and cannot be afforded at the preliminary stages of drug development programs. The strong conservation of the ERQC machinery across eukaryotes makes transgenic plants an attractive system for low-cost, easy and fast proof-of-concept screening of candidate ERQC inhibitors. The Arabidopsis thaliana immune response is mediated by glycoproteins, the folding of which is controlled by ERQC. We have used the plant response to bacterial peptides as a means of assaying an ERQC inhibitor in vivo. We show that the treatment of the plant with the iminosugar NB-DNJ, which is a known ER α-glucosidase inhibitor in mammals, influences the immune response of the plant to the bacterial peptide elf18 but not to the flagellin-derived flg22 peptide. In the NB-DNJ-treated plant, the responses to elf18 and flg22 treatments closely follow the ones observed for the ER α-glucosidase II impaired plant, At psl5-1. We propose Arabidopsis thaliana as a promising platform for the development of low-cost proof-of-concept in vivo ERQC modulation.

scholarly journals Functional evidence for in vitro microtubule severing by the plant katanin homologue

2002 ◽  
Vol 365 (2) ◽  
pp. 337-342 ◽  
Author(s):  
Virginie STOPPIN-MELLET ◽  
Jérémie GAILLARD ◽  
Marylin VANTARD
Keyword(s):  
Arabidopsis Thaliana ◽  
Plant Cells ◽  
Microtubule Assembly ◽  
Dependent Manner ◽  
Interacting Proteins ◽  
Microtubule Severing ◽  
Thale Cress ◽  
Temporal And Spatial

Temporal and spatial assembly of microtubules in plant cells depends mainly on the activity of microtubule-interacting proteins, which either stabilize, destabilize or translocate microtubules. Recent data have revealed that the thale cress (Arabidopsis thaliana) contains a protein related to the p60 catalytic subunit of animal katanin, a microtubule-severing protein. However, effects of the plant p60 on microtubule assembly are not known. We report the first functional evidence that the recombinant A. thaliana p60 katanin subunit, Atp60, binds to microtubules and severs them in an ATP-dependent manner in vitro. ATPase activity of Atp60 is stimulated by low tubulin/katanin ratios, and is inhibited at higher ratios. Considering its properties in vitro, several functions of Atp60 in vivo are discussed.

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