The structure and biological characteristics of the Spirochaeta aurantia outer membrane glycolipid LGL_B

Abstract

In an attempt to isolate lipopolysaccharide from Spirochaeta aurantia, Darveau-Hancock extraction of the cell mass was performed. While no lipopolysaccharide was found, two carbohydrate-containing compounds were detected. They were resolved by size-exclusion chromatography into high molecular mass (LGL A ) and low molecular mass (LGL B ) fractions. Here we present the results of the analysis of the glycolipid LGL B . Deacylation of LGL B with hydrazine and separation of the products by using anion-exchange chromatography gave two major products. Their structure was determined by using chemical methods, NMR and mass spectrometry. All monosaccharides had the D-configuration, and aspartic acid had the L-configuration. Intact LGL B contained two fatty groups at O-2 and O-3 of the glycerol residue. Nonhydroxylated C14 to C18 fatty acids were identified, which were predominantly unsaturated or branched.LGL B was able to gel Limulus amebocyte lysate, albeit at a lower level than that observed for Escherichia coli O113 lipopolysaccharide. However, even large amounts of LGL B were unable to stimulate any Toll-like receptor (TLR) examined, including TLR4 and TLR2, previously shown to be sensitive to lipopolysaccharide and glycolipids from diverse bacterial origins, including other spirochetes.

Ecophysiology of “ Halarsenatibacter silvermanii ” Strain SLAS-1 T , gen. nov., sp. nov., a Facultative Chemoautotrophic Arsenate Respirer from Salt-Saturated Searles Lake, California

“…A correlation of an increased proportion of unsaturated and branched-chain fatty acids with the presence of motility in Cytophaga has been observed (33). A relatively fluid outer membrane in Spirochaetes is thought to play an important role in the unique motility possessed by this group (58). The highly branched and unsaturated fatty acid composition of SLAS-1 T suggests a highly fluid membrane of potential importance to the unique style of motility and necessary flexibility of the cell envelope.…”

Involvement of Toll-Like Receptors 2 and 4 in the Innate Immune Response toTreponema denticolaand Its Outer Sheath Components

“…The presence of outer membrane diacylglycerol-containing glycolipids has been reported in different genera of spirochetes (21,28,39,40,52). These glycolipids share structural characteristics with lipoteichoic acids of gram-positive bacteria which also contain a diacylglycerol lipid anchor (16).…”

Characterization of the cell surface glycolipid from Spirochaeta aurantia

“…As a whole molecule, LGLA is too densely packed, which leads to signal broadening due to fast relaxation, which prevents detailed analysis of the intact structure by NMR. Large and extensively branched LGLA differs strikingly from most other known spirochete glycolipids, which contain only a few monosaccharides [7,8,14]. The only other non-LPS large carbohydrate structure reported in spirochetes was a polysaccharide isolated from a glycoconguate of the oral treponeme, Treponema medium [20], which also showed no endotoxin-like biological properties.…”

“…A low molecular weight fraction (LGLB) eluted near the end of the chromatogram and contained sugars and hexosamines. The biological and structural characterization of LGLB has been described [14].…”

“…LGLB is the smaller of the two, with a mass and carbohydrate structure that, while anchored on a glycerolipid instead of lipid A, resembles that of Ra LPS [14]. The present study investigates the biological nature and structure of the larger S. aurantia glycolipid, LGLA.…”