Endotoxin Structures in the Psychrophiles Psychromonas marina and Psychrobacter cryohalolentis Contain Distinctive Acyl Features |
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| Authors: | Charles R Sweet Giancarlo M Alpuche Corinne A Landis Benjamin C Sandman |
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| Institution: | 1.Chemistry Department, 572M Holloway Road, United States Naval Academy, Annapolis, MD 21402, USA; E-Mails: (G.M.A.); (C.A.L.); (B.C.S.);2.Belize Defense Force, Belize City P.O. Box 141, Belize;3.Penn State College of Medicine, 500 University Drive, Hershey, PA 17033, USA;4.US Navy SUBASE NL, Box 44, Groton, CT 06349, USA |
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| Abstract: | Lipid A is the essential component of endotoxin (Gram-negative lipopolysaccharide), a potent immunostimulatory compound. As the outer surface of the outer membrane, the details of lipid A structure are crucial not only to bacterial pathogenesis but also to membrane integrity. This work characterizes the structure of lipid A in two psychrophiles, Psychromonas marina and Psychrobacter cryohalolentis, and also two mesophiles to which they are related using MALDI-TOF MS and fatty acid methyl ester (FAME) GC-MS. P. marina lipid A is strikingly similar to that of Escherichia coli in organization and total acyl size, but incorporates an unusual doubly unsaturated tetradecadienoyl acyl residue. P. cryohalolentis also shows structural organization similar to a closely related mesophile, Acinetobacter baumannii, however it has generally shorter acyl constituents and shows many acyl variants differing by single methylene (-CH2-) units, a characteristic it shares with the one previously reported psychrotolerant lipid A structure. This work is the first detailed structural characterization of lipid A from an obligate psychrophile and the second from a psychrotolerant species. It reveals distinctive structural features of psychrophilic lipid A in comparison to that of related mesophiles which suggest constitutive adaptations to maintain outer membrane fluidity in cold environments. |
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| Keywords: | lipopolysaccharide lipid A lipid structure mass spectrometry psychrophile |
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