Structure of the Monophosphoryl Lipid A Moiety Obtained from the Lipopolysaccharide of Chlamydia trachomatis

Abstract

Monophosphoryl lipid A was prepared from the lipopolysaccharide of Chlamydia trachomatis, converted to the methyl ester, and fractionated by reverse-phase high-performance liquid chromatography. The peak fractions were collected and analyzed by mass spectrometry. Matrix-assisted laser desorption/ionization and liquid secondary ion mass spectrometry of the first of two major high-performance liquid chromatographic fractions showed multiple quasi-molecular ions of MNa+ at m/z 1780, 1794, 1808, 1822, and 1836. The positive-ion liquid secondary ion mass spectrometry spectrum also showed a minor series of peaks at m/z 1916, 1930, 1944, 1958, and 1971, consistent with the formation of matrix adducts with 3-nitrobenzyl alcohol. Oxonium ions representing the distal subunit were observed at m/z 1057, 1071, 1085, 1099, and 1113. The second fraction was similarly analyzed and found to contain structural homologs of the first fraction. Based on this study, the major lipid A component of chlamydial lipopolysaccharide is a glucosamine disaccharide that contains five fatty acids and a phosphate in the distal segment. Three fatty acyl groups are in the distal segment, and two are in the reducing end segment. The acyloxyacyl group is located in the distal segment in amide linkage. Two structural series, differing by 14 atomic mass units in the reducing subunit, were observed. Chlamydial lipid A is complex and consists of at least 20 homologous structural components. The relatively low potency of Chlamydia trachomatis lipopolysaccharide in activating lipopolysaccharide-responsive cells might be related to the unusual fatty acid composition of the lipid A moiety.

Type II Fatty Acid Synthesis Is Essential for the Replication of Chlamydia trachomatis

“…This bioinformatics analysis predicts that C. trachomatis has the gene set for the synthesis of branched-chain and hydroxy fatty acids that cannot be obtained from the host. Branched-chain fatty acids are incorporated into chlamydial phospholipids (26), and the straight-chain 3-hydroxy fatty acids are found in the LOS of this organism (27)(28)(29). The gene(s) for unsaturated fatty acid synthesis are absent.…”

Susceptibility of Prostate Epithelial Cells toChlamydia muridarumInfection and Their Role in Innate Immunity by Recruitment of Intracellular Toll-Like Receptors 4 and 2 and MyD88 to the Inclusion

“…For example, cLPS has been extensively studied (35) and has been found to have low endotoxic activity (16); it is currently under discussion whether LPS signals through TLR4 or TLR2 (13,34). A second important Chlamydia antigen is the heat shock protein.…”

A Chlamydia trachomatisUDP-N-Acetylglucosamine Acyltransferase Selective for Myristoyl-Acyl Carrier Protein

“…However, the 3 and 3Ј acyl chains of lipid A are not hydroxylated in Chlamydia trachomatis (Fig. 2), an intracellular Gram-negative pathogen with a biphasic life cycle and a chronic inflammatory pathology (3,18,19). Ocular infections with C. trachomatis are the leading worldwide cause of preventable blindness (20,21).…”