Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a major cause of foodborne gastrointestinal illness. The adhesion of EHEC to host tissues is the first step enabling bacterial colonization. Adhesins such as fimbriae and flagella mediate this process. Here, we studied the interaction of the bacterial flagellum with the host cell's plasma membrane using giant unilamellar vesicles (GUVs) as a biologically relevant model. Cultured cell lines contain many different molecular components, including proteins and glycoproteins. In contrast, with GUVs, we can characterize the bacterial mode of interaction solely with a defined lipid part of the cell membrane. Bacterial adhesion on GUVs was dependent on the presence of the flagellar filament and its motility. By testing different phospholipid head groups, the nature of the fatty acid chains, or the liposome curvature, we found that lipid packing is a key parameter to enable bacterial adhesion. Using HT-29 cells grown in the presence of polyunsaturated fatty acid (α-linolenic acid) or saturated fatty acid (palmitic acid), we found that α-linolenic acid reduced adhesion of wild-type EHEC but not of a nonflagellated mutant. Finally, our results reveal that the presence of flagella is advantageous for the bacteria to bind to lipid rafts. We speculate that polyunsaturated fatty acids prevent flagellar adhesion on membrane bilayers and play a clear role for optimal host colonization. Flagellum-mediated adhesion to plasma membranes has broad implications for host-pathogen interactions.IMPORTANCE Bacterial adhesion is a crucial step to allow bacteria to colonize their hosts, invade tissues, and form biofilm. Enterohemorrhagic Escherichia coli O157:H7 is a human pathogen and the causative agent of diarrhea and hemorrhagic colitis. Here, we use biomimetic membrane models and cell lines to decipher the impact of lipid content of the plasma membrane on enterohemorrhagic E. coli flagellum-mediated adhesion. Our findings provide evidence that polyunsaturated fatty acid (α-linolenic acid) inhibits E. coli flagellar adhesion to the plasma membrane in a mechanism separate from its antimicrobial and anti-inflammatory functions. In addition, we confirm that cholesterol-enriched lipid microdomains, often called lipid rafts, are important in bacterial adhesion. These findings demonstrate that plasma membrane adhesion via bacterial flagella play a significant role for an important human pathogen. This mechanism represents a promising target for the development of novel antiadhesion therapies.
- MeSH
- bakteriální adheze * MeSH
- buněčná membrána chemie MeSH
- buněčné linie MeSH
- buňky HT-29 MeSH
- epitelové buňky mikrobiologie MeSH
- Escherichia coli O157 fyziologie MeSH
- flagella metabolismus MeSH
- fosfolipidy analýza MeSH
- interakce hostitele a patogenu * MeSH
- kyselina alfa-linolenová analýza MeSH
- kyselina palmitová analýza MeSH
- lidé MeSH
- membránové mikrodomény chemie MeSH
- unilamelární lipozómy chemie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
A terrestrial green microalga was isolated at Ås, in Akershus County, Norway. The strain corresponded to a coccoid chlorophyte. Morphological characteristics by light and electron microscopy, in conjunction with DNA amplification and sequencing of the 18 s rDNA gene and ITS sequences, were used to identify the microalgae. The characteristics agree with those of the genus Coelastrella defined by Chodat, and formed a sister group with the recently described C. thermophila var. globulina. Coelastrella is a relatively small numbered genus that has not been observed in continental Norway before; there are no previous cultures available in collections of Norwegian strains. Gas chromatography analyses of the FAME-derivatives showed a high percentage of polyunsaturated fatty acids (44-45%) especially linolenic acid (C18:3n3; 30-34%). After the stationary phase, the cultures were able to accumulate several carotenoids as neoxanthin, pheophytin a, astaxanthin, canthaxanthin, lutein, and violaxanthin. Due to the scarcity of visual characters suitable for diagnostic purposes and the lack of DNA sequence information, there is a high possibility that species of this genus have been neglected in local environmental studies, even though it showed interesting properties for algal biotechnology.
- MeSH
- biologické pigmenty analýza MeSH
- biotechnologie MeSH
- Chlorophyta klasifikace cytologie genetika MeSH
- druhová specificita MeSH
- feofytiny analýza MeSH
- fylogeneze * MeSH
- karotenoidy analýza MeSH
- kyselina alfa-linolenová analýza MeSH
- mastné kyseliny analýza MeSH
- mikrořasy klasifikace cytologie genetika izolace a purifikace MeSH
- ribozomální DNA MeSH
- RNA ribozomální 18S genetika MeSH
- xanthofyly MeSH
- Publikační typ
- časopisecké články MeSH
- Geografické názvy
- Norsko MeSH
The objective of the study is to standardize GC determination of polyunsaturated fatty acids in animal tissues by lipid extraction with a hexane/propan-2-ol mixture and subsequent derivatization with CH3ONa/BF3. The limits of detection and recoveries for 18:2n-6, 20:4n-6, 18:3n-3, 20:5n-3, 22:5n-3 and 22:6n-3 fatty acids was in the range 0.32–0.42 mg/100 g, and 83–105 %, respectively. The content of physiologically important icosapentaenoic acid (EPA) in chicken breast meat, thigh meat, quail eggs and cricket nymphs was 3, 10, 51 and 21 mg/100 g of fresh matter (P < 0.05). The EPA contents in livers of laboratory rats fed diets supplemented with palm oil, safflower oil and fish oil was 4, 3 and 342 mg/100 g, respectively (P < 0.05).
- MeSH
- cholesterol metabolismus MeSH
- chromatografie plynová * metody přístrojové vybavení využití MeSH
- experimenty na zvířatech MeSH
- kardiovaskulární nemoci prevence a kontrola MeSH
- kyselina alfa-linolenová analýza MeSH
- kyselina eikosapentaenová analýza MeSH
- kyseliny dokosahexaenové analýza MeSH
- lidé MeSH
- lipidy analýza MeSH
- nenasycené mastné kyseliny * analýza MeSH
- tkáňové extrakty analýza MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- práce podpořená grantem MeSH
