Loss of carotenoids from membranes of Pantoea sp. YR343 results in altered lipid composition and changes in membrane biophysical properties
| Autor: | Sushmitha Vijaya Kumar, Amber N. Bible, Graham Taylor, Abigail T. Farmer, Shawn R. Campagna, Mitchel J. Doktycz, Jennifer L. Morrell-Falvey, C. Patrick Collier, Sahar Hasim |
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| Rok vydání: | 2019 |
| Předmět: |
Membrane Fluidity
Biophysics Fluorescence Polarization Biochemistry Biophysical Phenomena Cell wall 03 medical and health sciences Membrane fluidity Secretion 030304 developmental biology 0303 health sciences biology Pantoea 030306 microbiology Chemistry Vesicle Cell Membrane Fatty Acids Wild type Cell Biology Lipid Metabolism biology.organism_classification Carotenoids Membrane Membrane protein |
| Zdroj: | Biochimica et Biophysica Acta (BBA) - Biomembranes. 1861:1338-1345 |
| ISSN: | 0005-2736 |
| DOI: | 10.1016/j.bbamem.2019.05.009 |
| Popis: | Bacterial membranes are complex mixtures of lipids and proteins, the combination of which confers biophysical properties that allows cells to respond to environmental conditions. Carotenoids are sterol analogs that are important for regulating membrane dynamics. The membrane of Pantoea sp. YR343 is characterized by the presence of the carotenoid zeaxanthin, and a carotenoid-deficient mutant, ΔcrtB, displays defects in root colonization, reduced secretion of indole-3-acetic acid, and defects in biofilm formation. Here we demonstrate that the loss of carotenoids results in changes to the membrane lipid composition in Pantoea sp. YR343, including increased amounts of unsaturated fatty acids in the ΔcrtB mutant membranes. These mutant cells displayed less fluid membranes in comparison to wild type cells as measured by fluorescence anisotropy of whole cells. Studies with artificial systems, however, have shown that carotenoids impart membrane rigidifying properties. Thus, we examined membrane fluidity using spheroplasts and vesicles composed of lipids extracted from either wild type or mutant cells. Interestingly, with the removal of the cell wall and membrane proteins, ΔcrtB vesicles were more fluid than vesicles made from lipids extracted from wild type cells. In addition, carotenoids appeared to stabilize membrane fluidity during rapidly changing temperatures. Taken together, these results suggest that Pantoea sp. YR343 compensates for the loss of carotenoids by changing lipid composition, which together with membrane proteins, results in reduced membrane fluidity. These changes may influence the abundance or function of membrane proteins that are responsible for the physiological changes observed in the ΔcrtB mutant cells. |
| Databáze: | OpenAIRE |
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