title: Endotoxin structures in the psychrophiles Psychromonas marina and Psychrobacter cryohalolentis contain distinctive acyl features.
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.
authors.affiliation: Chemistry Department, 572M Holloway Road, United States Naval Academy, Annapolis, MD 21402, USA. sweet@usna.edu.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Sweet
authors.affiliation: Chemistry Department, 572M Holloway Road, United States Naval Academy, Annapolis, MD 21402, USA. gpuche84@gmail.com.
authors.forename: Giancarlo M
authors.initials: GM
authors.lastname: Alpuche
authors.affiliation: Chemistry Department, 572M Holloway Road, United States Naval Academy, Annapolis, MD 21402, USA. clandis@hmc.psu.edu.
authors.forename: Corinne A
authors.initials: CA
authors.lastname: Landis
authors.affiliation: Chemistry Department, 572M Holloway Road, United States Naval Academy, Annapolis, MD 21402, USA. bensandman2@gmail.com.
authors.forename: Benjamin C
authors.initials: BC
authors.lastname: Sandman
mesh_terms: D004926:Escherichia coli / Q000737:chemistry; D020563:Gammaproteobacteria / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry; D008050:Lipid A / Q000737:chemistry*; D044096:Psychrobacter / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D008050:Lipid A