The effect of zeaxanthin on the thickness of dimyristoylphosphatidylcholine bilayer: X-ray diffraction study

Gruszecki, Wiesław I.; Smal, A. N.; Szymczuk, D.

doi:10.1007/bf00419424

Cited by 18 publications

(14 citation statements)

References 13 publications

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“…The Q8 molecule has been shown to reside flat in the center of the lipid bilayer 32,39 , implying that the observed substantial accumulation of Q8 would increase the hydrophobic thickness of the cytoplasmic membrane. Intriguingly, such an effect has already been observed in vitro with the isoprenoid zeaxanthin, of which concentrations between 1% and 10% increased the hydrophobic thickness of artificial lipid bilayer membranes 40 .…”

Section: Discussionmentioning

confidence: 76%

Ubiquinone accumulation improves osmotic-stress tolerance in Escherichia coli

2014

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Bacteria are thought to cope with fluctuating environmental solute concentrations primarily by adjusting the osmolality of their cytoplasm. To obtain insights into underlying metabolic adaptions, we analyzed the global metabolic response of Escherichia coli to sustained hyperosmotic stress using non-targeted mass spectrometry. We observed that 52% of 1,071 detected metabolites, including known osmoprotectants, changed abundance with increasing salt challenge. Unexpectedly, unsupervised data analysis revealed a substantial increase of most intermediates in the ubiquinone-8 (Q8) biosynthesis pathway and a 110-fold accumulation of Q8 itself, as confirmed by quantitative lipidomics. We then demonstrate that Q8 is necessary for acute and sustained osmotic stress tolerance using Q8 mutants and tolerance rescue through feeding non-respiratory Q8 analogues. Finally, in vitro experiments with artificial liposomes reveal mechanical membrane stabilization as a principal mechanism of Q8-mediated osmoprotection. Thus, we find that besides regulating intracellular osmolality, E. coli enhances its cytoplasmic membrane stability to withstand osmotic stress. AbstractBacteria are thought to cope with fluctuating environmental solute concentrations primarily by adjusting the osmolality of their cytoplasm. To obtain insights into underlying metabolic adaptions, we analyzed the global metabolic response of Escherichia coli to sustained hyperosmotic stress using non-targeted mass spectrometry. We observed that 52% of 1,071 detected metabolites, including known osmoprotectants, changed abundance with increasing salt challenge. Unexpectedly, unsupervised data analysis revealed a substantial increase of most intermediates in the ubiquinone-8 (Q8) biosynthesis pathway and a 110-fold accumulation of Q8 itself, as confirmed by quantitative lipidomics. We then demonstrate that Q8 is necessary for acute and sustained osmotic stress tolerance using Q8 mutants and tolerance rescue through feeding non-respiratory Q8 analogues.Finally, in vitro experiments with artificial liposomes reveal mechanical membrane stabilization as a principal mechanism of Q8-mediated osmoprotection. Thus, we find that besides regulating intracellular osmolality, E. coli enhances its cytoplasmic membrane stability to withstand osmotic stress.

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Section: Discussionmentioning

confidence: 76%

Ubiquinone accumulation improves osmotic-stress tolerance in Escherichia coli

2014

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“…It was shown that all-trans isomers of dipolar xanthophylls affect the properties of thin membranes (DLPC, DMPC) more strongly than the properties of thick membranes (DPPC, DSPC, DBPC) [22,24], presumably because in thin membranes these dipolar xanthophylls are tilted with respect to the bilayer normal [10,57,58,59,60] and interact with the larger number of alkyl chains. Thus, the effect of the tilted cis-isomer should be stronger than the effect of the less-tilted trans-isomer.…”

Section: Discussionmentioning

confidence: 99%

Transmembrane localization of cis-isomers of zeaxanthin in the host dimyristoylphosphatidylcholine bilayer membrane

Widomska

Subczynski

2008

Biochimica et Biophysica Acta (BBA) - Biomembranes

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The effects of the 9-cis and 13-cis isomers of zeaxanthin on the molecular organization and dynamics of dimyristoylphosphatidylcholine (DMPC) membranes were investigated using conventional and saturation recovery EPR observations of the 1-palmitoyl-2-(14-doxylstearoyl)phosphatidylcholine (14-PC) spin label. The results were compared with the effects caused by the all-trans isomer of zeaxanthin. Effects on membrane fluidity, order, hydrophobicity, and the oxygen transport parameter were monitored at the center of the fluid phase DMPC membrane. The local diffusion-solubility product of oxygen molecules (oxygen transport parameter) in the membrane center, studied by saturation-recovery EPR, decreased by 47% and 27% by including 10 mol% 13-cis and 9-cis zeaxanthin, respectively; whereas, incorporation of all-trans zeaxanthin decreased this parameter by only 11%. At a zeaxanthin-to-DMPC mole ratio of 1:9, all investigated isomers decreased the membrane fluidity and increased the alkyl chain order in the membrane center. They also increased the hydrophobicity of the membrane interior. The effects of these isomers of zeaxanthin on the membrane properties mentioned above increase as: all-trans<9-cis

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“…22,26,27 These changes in membrane thermodynamics suggest that LUT and ZEA aggregate within the lipid bilayer and the extent of aggregation is dependent on carotenoid concentration. 17,22,[27][28][29][30][31] Further, MLVs that contain 0.5 mol% carotenoids exhibited similar melting temperatures (T m ), as well as other basic thermodynamic parameters (ΔH and ΔS), as compared to control MLVs (Fig. 2D, S1C and D †).…”

Section: Resultsmentioning

confidence: 77%

“…The decrease in membrane fluidity at the hydrophobic region by LUT and ZEA is likely due to restrictions on molecular motion of the acyl tails as carotenoids interact with the acyl tails via Van de Waals and hydrophobic interations. 16,30,32 In probing the hydrophilic region, both LUT-MLVs and ZEA-MLVs were also observed to have higher Prodan GP values than control MLVs at all carotenoid concentrations except at 10 mol% (Fig. 3F).…”

Section: Resultsmentioning

confidence: 93%

“…We infer that the molecular aggregation observed at high carotenoid concentrations promotes the formation of carotenoid-rich domains within the lipid bilayer, where the Van de Waals and hydrophobic interactions between acyl tails and carotenoids are likely to be more dominant than interactions between neighboring acyl tails. 30,32 These carotenoid-rich nanodomains in MLVs are instrumental in modulating membrane thermodynamics, which is parallel to lipid nanodomains in biological membranes, that are functional for facilitating membrane-associated cellular processes. 33,34 Polar carotenoids decrease fluidity and water permeability of the hydrophobic regions in lipid bilayers Membrane fluidity was probed at different regions of the lipid bilayer using Prodan and Laurdan, where Prodan probes at the headgroups (hydrophilic region) and Laurdan probes at the hydrophobic region given its longer hydrocarbon chain (Fig.…”

Section: Resultsmentioning

confidence: 99%

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