Showing papers on "Polyamine binding published in 2014"

Inhibition of the polyamine system counteracts β-amyloid peptide-induced memory impairment in mice: involvement of extrasynaptic NMDA receptors.

Abstract: In Alzheimer's disease (AD), the β-amyloid peptide (Aβ) has been causally linked to synaptic dysfunction and cognitive impairment. Several studies have shown that N-Methyl-D-Aspartate receptors (NMDAR) activation is involved in the detrimental actions of Aβ. Polyamines, like spermidine and spermine, are positive modulators of NMDAR function and it has been shown that their levels are regulated by Aβ. In this study we show here that interruption of NMDAR modulation by polyamines through blockade of its binding site at NMDAR by arcaine (0.02 nmol/site), or inhibition of polyamine synthesis by DFMO (2.7 nmol/site), reverses Aβ25–35-induced memory impairment in mice in a novel object recognition task. Incubation of hippocampal cell cultures with Aβ25–35 (10 µM) significantly increased the nuclear accumulation of Jacob, which is a hallmark of NMDAR activation. The Aβ-induced nuclear translocation of Jacob was blocked upon application of traxoprodil (4 nM), arcaine (4 µM) or DFMO (5 µM), suggesting that activation of the polyamine binding site at NMDAR located probably at extrasynaptic sites might underlie the cognitive deficits of Aβ25–35-treated mice. Extrasynaptic NMDAR activation in primary neurons results in a stripping of synaptic contacts and simplification of neuronal cytoarchitecture. Aβ25–35 application in hippocampal primary cell cultures reduced dendritic spine density and induced alterations on spine morphology. Application of traxoprodil (4 nM), arcaine (4 µM) or DFMO (5 µM) reversed these effects of Aβ25–35. Taken together these data provide evidence that polyamine modulation of extrasynaptic NMDAR signaling might be involved in Aβ pathology.

Polyamine transporters and polyamines increase furfural tolerance during xylose fermentation with ethanologenic Escherichia coli strain LY180.

Abstract: Expression of genes encoding polyamine transporters from plasmids and polyamine supplements increased furfural tolerance (growth and ethanol production) in ethanologenic Escherichia coli LY180 (in AM1 mineral salts medium containing xylose). This represents a new approach to increase furfural tolerance and may be useful for other organisms. Microarray comparisons of two furfural-resistant mutants (EMFR9 and EMFR35) provided initial evidence for the importance of polyamine transporters. Each mutant contained a single polyamine transporter gene that was upregulated over 100-fold (microarrays) compared to that in the parent LY180, as well as a mutation that silenced the expression of yqhD. Based on these genetic changes, furfural tolerance was substantially reconstructed in the parent, LY180. Deletion of potE in EMFR9 lowered furfural tolerance to that of the parent. Deletion of potE and puuP in LY180 also decreased furfural tolerance, indicating functional importance of the native genes. Of the 8 polyamine transporters (18 genes) cloned and tested, half were beneficial for furfural tolerance (PotE, PuuP, PlaP, and PotABCD). Supplementing AM1 mineral salts medium with individual polyamines (agmatine, putrescine, and cadaverine) also increased furfural tolerance but to a smaller extent. In pH-controlled fermentations, polyamine transporter plasmids were shown to promote the metabolism of furfural and substantially reduce the time required to complete xylose fermentation. This increase in furfural tolerance is proposed to result from polyamine binding to negatively charged cellular constituents such as nucleic acids and phospholipids, providing protection from damage by furfural.

Interaction of linear polyamines with negatively charged phospholipids: the effect of polyamine charge distance

Abstract: The binding of cationic polyamines to negatively charged lipid membranes is driven by electrostatic interactions and additional hydrophobic contributions. We investigated the effect of polyamines with different number of charges and charge separation on the phase transition behavior of vesicles of phosphatidylglycerols (dipalmitoylphosphatidylglycerol and dimyristoylphosphatidylglycerol) to differentiate between effects caused by the number of charges, the charge distance, and the hydrophobicity of the methylene spacer. Using differential scanning calorimetry and Fourier transform infrared spectroscopy complemented with monolayer experiments, we found that the binding constant of polyamines to negatively charged lipid vesicles depends as expected on the number of charges. However, for diamines, the effect of binding on the main phase transition of phosphatidylglycerols (PGs) is also strongly influenced by the charge distance between the ammonium groups in the backbone. Oligoamines with charges separated by two or three methylene groups bind more strongly and have larger stabilizing effects on the lipid gel phase of PGs. With multivalent polyamines, the appearance of several transition peaks points to effects of molecular crowding on the surface, i.e., binding of only two or three charges to the surface in the case of spermine, and possible concomitant domain formation.

Encapsulation of biogenic and synthetic polyamines by nanoparticles PEG and mPEG-anthracene

Abstract: Synthetic polymers play a major role in drug delivery in vitro and in vivo. We report the bindings of biogenic polyamines, spermine (spm), and spermidine (spmd), and their synthetic analogues, 3,7,11,15-tetrazaheptadecane⋅4HCl (BE-333) and 3,7,11,15,19-pentazahenicosane⋅5HCl (BE-3333) with poly(ethylene glycol) PEG-3000, PEG-8000 and methoxy poly(ethylene glycol) anthracene (PEG-anthracene). Fourier transform infrared (FTIR), UV-visible and fluorescence spectroscopic were used to analyze polyamine binding mode, the binding constant and the effect of PEG compositions on polyamine-polymer interaction. Structural analysis showed that polyamines bind PEG through hydrophobic and hydrophilic contacts with overall binding constants of Kspm-PEG-3000=3.1×10(4)M(-1), Kspmd-PEG-3000=5.5×10(4)M(-1), KBE-333-PEG-3000=2.5×10(4)M(-1), KBE-3333-PEG-3000=1.5×10(5)M(-1), Kspm-PEG-8000=4.1×10(5)M(-1), Kspmd-PEG-8000=7.5×10(5)M(-1), KBE-333-PEG-8000=4.5×10(4)M(-1), KBE-3333-PEG-8000=2.2×10(5)M(-1), Kspm-mPEG-ant=6.5×10(5)M(-1), Kspmd-mPEG-ant=1.1×10(6)M(-1), KBE-333-mPEG-ant=2.2×10(5)M(-1) and KBE-3333-mPEG-ant=6.9×10(4)M(-1). The number of binding sites (n) occupied by polyamines were from 0.2 to 0.5. Biogenic polyamines showed stronger affinity toward polymer complexation than synthetic polyamines, while weaker interaction was observed as polyamine cationic charges increased. Our results suggest that PEG and its derivative can act as carriers for delivering antitumor polyamine analogues to target tissues.

Involvement of Polyamine Binding Protein D (PotD) of Synechocystis sp. PCC 6803 in Spermidine Uptake and Excretion

Abstract: The in vivo function of polyamine binding protein D (PotD) in Synechocystis sp. PCC 6803 for the transport of spermidine was investigated using Synechocystis mutant disrupted in potD gene. The growth rate of potD mutant was similar to that of wild-type when grown in BG11 medium. However, the mutant exhibited severely reduced growth compared to the wild-type when BG11 medium was supplemented with 0.5 mM spermidine. The mutant accumulated a higher spermidine level than the wild-type when grown in the medium with or without spermidine. Transport experiments revealed that the mutant had a reduction in both the uptake and the excretion of spermidine. Moreover, [14C]spermidine-loaded wild-type and mutant cells showed a decrease of [14C]spermidine excretion when the assay medium contained exogenous spermidine. These data suggest that PotD is involved in both the uptake and the excretion of spermidine in Synechocystis cells.