bims-polyam 2020-03-01 papers

on Polyamines

Issue of 2020–03–01
six papers selected by
Sebastian J. Hofer, University of Graz and Alexander Ivanov, Engelhardt Institute of Molecular Biology

Polyamine stimulation perturbs intracellular Ca2+ homeostasis and decreases viability of breast cancer BT474 cells.
KLF4 is required for suppression of histamine synthesis by polyamines during bone marrow-derived mast cell differentiation.
Ornithine capture by a translating ribosome controls bacterial polyamine synthesis.
γ-Aminobutyric acid confers cadmium tolerance in maize plants by concerted regulation of polyamine metabolism and antioxidant defense systems.
16S rRNA sequence data of Bombyx mori gut bacteriome after spermidine supplementation.
Designing heterotropically activated allosteric conformational switches using supercharging.

Z Naturforsch C J Biosci. 2020 Feb 24. pii: /j/znc.ahead-of-print/znc-2019-0119/znc-2019-0119.xml. [Epub ahead of print]

Polyamine stimulation perturbs intracellular Ca2+ homeostasis and decreases viability of breast cancer BT474 cells.

Louis W C Chow, Kar-Lok Wong, Lian-Ru Shiao, King-Chuen Wu, Yuk-Man Leung.

  Intracellular polyamines such as spermine and spermidine are essential to cell growth in normal and especially in cancer cells. However, whether extracellular polyamines affect cancer cell survival is unknown. We therefore examined the actions of extracellular polyamines on breast cancer BT474 cells. Our data showed that spermine, spermidine, and putrescine decreased cell viability by apoptosis. These polyamines also elicited Ca2+ signals, but the latter were unlikely triggered via Ca2+-sensing receptor (CaSR) as BT474 cells have been demonstrated previously to lack CaSR expression. Spermine-elicited Ca2+ response composed of both Ca2+ release and Ca2+ influx. Spermine caused a complete discharge of the cyclopiazonic acid (CPA)-sensitive Ca2+ pool and, expectedly, endoplasmic reticulum (ER) stress. The Ca2+ influx pore opened by spermine was Mn2+-impermeable, distinct from the CPA-triggered store-operated Ca2+ channel, which was Mn2+-permeable. Spermine cytotoxic effects were not due to oxidative stress, as spermine did not trigger reactive oxygen species formation. Our results therefore suggest that spermine acted on a putative polyamine receptor in BT474 cells, causing cytotoxicity by Ca2+ overload, Ca2+ store depletion, and ER stress.

Keywords:  BT474; Ca2+; breast cancer; cytotoxicity; putrescine; spermidine; spermine

DOI:  https://doi.org/10.1515/znc-2019-0119
PLoS One. 2020 ;15(2): e0229744

KLF4 is required for suppression of histamine synthesis by polyamines during bone marrow-derived mast cell differentiation.

Kazuhiro Nishimura, Moemi Okamoto, Rina Shibue, Toshio Mizuta, Toru Shibayama, Tetsuhiko Yoshino, Teruki Murakami, Masashi Yamaguchi, Satoshi Tanaka, Toshihiko Toida, Kazuei Igarashi.

Mast cells have secretory granules containing chemical mediators such as histamine and play important roles in the immune system. Polyamines are essential factors for cellular processes such as gene expression and translation. It has been reported that secretory granules contain both histamine and polyamines, which have similar chemical structures and are produced from the metabolism of cationic amino acids. We investigated the effect of polyamine depletion on mast cells using bone marrow-derived mast cells (BMMCs). Polyamine depletion was induced using α-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase. DFMO treatment resulted in a significant reduction of cell number and abnormal secretory granules in BMMCs. Moreover, the cells showed a 2.3-fold increase in intracellular histamine and up-regulation of histidine decarboxylase (HDC) at the transcriptional level during BMMC differentiation. Levels of the transcription factor kruppel-like factor 4 (KLF4) greatly decreased upon DFMO treatment; however, Klf4 mRNA was expressed at levels similar to controls. We determined the translational regulation of KLF4 using reporter genes encoding Klf4-luc2 fusion mRNA, for transfecting NIH3T3 cells, and performed in vitro translation. We found that the efficiency of KLF4 synthesis in response to DFMO treatment was enhanced by the existence of a GC-rich 5'-untranslated region (5'-UTR) on Klf4 mRNA, regardless of the recognition of the initiation codon. Taken together, these results indicate that the enhancement of histamine synthesis by DFMO depends on the up-regulation of Hdc expression, achieved by removal of transcriptional suppression of KLF4, during differentiation.

DOI: https://doi.org/10.1371/journal.pone.0229744
Nat Microbiol. 2020 Feb 24.

Ornithine capture by a translating ribosome controls bacterial polyamine synthesis.

Alba Herrero Del Valle, Britta Seip, Iñaki Cervera-Marzal, Guénaël Sacheau, A Carolin Seefeldt, C Axel Innis.

Polyamines are essential metabolites that play an important role in cell growth, stress adaptation and microbial virulence1-3. To survive and multiply within a human host, pathogenic bacteria adjust the expression and activity of polyamine biosynthetic enzymes in response to different environmental stresses and metabolic cues2. Here, we show that ornithine capture by the ribosome and the nascent peptide SpeFL controls polyamine synthesis in γ-proteobacteria by inducing the expression of the ornithine decarboxylase SpeF4, via a mechanism involving ribosome stalling and transcription antitermination. In addition, we present the cryogenic electron microscopy structure of an Escherichia coli ribosome stalled during translation of speFL in the presence of ornithine. The structure shows how the ribosome and the SpeFL sensor domain form a highly selective binding pocket that accommodates a single ornithine molecule but excludes near-cognate ligands. Ornithine pre-associates with the ribosome and is then held in place by the sensor domain, leading to the compaction of the SpeFL effector domain and blocking the action of release factor 1. Thus, our study not only reveals basic strategies by which nascent peptides assist the ribosome in detecting a specific metabolite, but also provides a framework for assessing how ornithine promotes virulence in several human pathogens.

DOI: https://doi.org/10.1038/s41564-020-0669-1
Sci Rep. 2020 Feb 25. 10(1): 3356

γ-Aminobutyric acid confers cadmium tolerance in maize plants by concerted regulation of polyamine metabolism and antioxidant defense systems.

Maryam Seifikalhor, Sasan Aliniaeifard, Françoise Bernard, Mehdi Seif, Mojgan Latifi, Batool Hassani, Fardad Didaran, Massimo Bosacchi, Hassan Rezadoost, Tao Li.

Gamma-Aminobutyric acid (GABA) accumulates in plants following exposure to heavy metals. To investigate the role of GABA in cadmium (Cd) tolerance and elucidate the underlying mechanisms, GABA (0, 25 and 50 µM) was applied to Cd-treated maize plants. Vegetative growth parameters were improved in both Cd-treated and control plants due to GABA application. Cd uptake and translocation were considerably inhibited by GABA. Antioxidant enzyme activity was enhanced in plants subjected to Cd. Concurrently GABA caused further increases in catalase and superoxide dismutase activities, which led to a significant reduction in hydrogen peroxide, superoxide anion and malondealdehyde contents under stress conditions. Polyamine biosynthesis-responsive genes, namely ornithine decarboxylase and spermidine synthase, were induced by GABA in plants grown under Cd shock. GABA suppressed polyamine oxidase, a gene related to polyamine catabolism, when plants were exposed to Cd. Consequently, different forms of polyamines were elevated in Cd-exposed plants following GABA application. The maximum quantum efficiency of photosystem II (Fv/Fm) was decreased by Cd-exposed plants, but was completely restored by GABA to the same value in the control. These results suggest a multifaceted contribution of GABA, through regulation of Cd uptake, production of reactive oxygen species and polyamine metabolism, in response to Cd stress.

DOI: https://doi.org/10.1038/s41598-020-59592-1
BMC Res Notes. 2020 Feb 24. 13(1): 94

16S rRNA sequence data of Bombyx mori gut bacteriome after spermidine supplementation.

Resma Rajan, Alekhya Rani Chunduri, Anugata Lima, Anitha Mamillapalli.

   OBJECTIVES: The silkworm Bombyx mori (B. mori) is an important domesticated lepidopteran model for basic and applied research. They produce silk fibres that have great economic value. The gut microbiome plays an important role in the growth of organisms. Spermidine (Spd) is shown to be important for the growth of all living cells. The effect of spermidine feeding on the gut microbiome of 5th instar B. mori larvae was checked. The B. mori gut samples from control and spermidine fed larvae were subjected to next-generation sequencing analysis to unravel changes in the bacterial community upon spermidine supplementation.
DATA DESCRIPTION: The changes in gut bacteriota after spermidine feeding is not studied before. B. mori larvae were divided into two groups of 50 worms each and were fed with normal mulberry leaves and mulberry leaves fortified with 50 µM spermidine. The gut tissues were isolated aseptically and total genomic DNA was extracted, 16S rRNA region amplified and sequenced using Illumina platform. The spermidine fed gut samples were shown to have abundance and diversity of the phyla Proteobacteria, Firmicutes, Bacteroidetes, and Actinobacteria.

Keywords:  Bombyx mori; Gut; Metagenome; Microbiome; Spermidine

DOI:  https://doi.org/10.1186/s13104-020-04958-x
Proc Natl Acad Sci U S A. 2020 Feb 25. pii: 201916046. [Epub ahead of print]

Designing heterotropically activated allosteric conformational switches using supercharging.

Peter J Schnatz, Joseph M Brisendine, Craig C Laing, Bernard H Everson, Cooper A French, Paul M Molinaro, Ronald L Koder.

  Heterotropic allosteric activation of protein function, in which binding of one ligand thermodynamically activates the binding of another, different ligand or substrate, is a fundamental control mechanism in metabolism and as such has been a long-aspired capability in protein design. Here we show that greatly increasing the magnitude of a protein's net charge using surface supercharging transforms that protein into an allosteric ligand- and counterion-gated conformational molecular switch. To demonstrate this we first modified the designed helical bundle hemoprotein H4, creating a highly charged protein which both unfolds reversibly at low ionic strength and undergoes the ligand-induced folding transition commonly observed in signal transduction by intrinsically disordered proteins in biology. As a result of the high surface-charge density, ligand binding to this protein is allosterically activated up to 1,300-fold by low concentrations of divalent cations and the polyamine spermine. To extend this process further using a natural protein, we similarly modified Escherichia coli cytochrome b 562 and the resulting protein behaves in a like manner. These simple model systems not only establish a set of general engineering principles which can be used to convert natural and designed soluble proteins into allosteric molecular switches useful in biodesign, sensing, and synthetic biology, the behavior we have demonstrated--functional activation of supercharged intrinsically disordered proteins by low concentrations of multivalent ions--may be a control mechanism utilized by Nature which has yet to be appreciated.

Keywords:  allostery; intrinsically disordered proteins; ligand-induced folding; protein design; supercharging

DOI:  https://doi.org/10.1073/pnas.1916046117