Identification of the surface-exposed lipids on the cell envelopes of Mycobacterium tuberculosis and other mycobacterial species

Abstract

The surface-exposed lipids of Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium kansasii, Mycobacterium gastri, Mycobacterium smegmatis, and Mycobacterium aurum were isolated by gentle mechanical treatment of cells with glass beads. Analysis of the exposed lipids demonstrated a selective location of classes of ubiquitous lipids on the surfaces of mycobacteria. While phosphatidylethanolamine and phosphatidylinositol mannosides were exposed in all the species examined, dimycoloyl trehalose (''cord factor'') was identified in the surface components of M. aurum only. Furthermore, monomycoloyl trehaloses and triacylglycerides were identified in the surface-exposed lipids of M. avium and M. smegmatis but not in those of the other mycobacterial species examined. The species-and type-species specific lipids were present on the mycobacterial cell surface: phenolic glycolipids, dimycocerosates of phthiocerols, and lipooligosaccharides were identified in the surface-exposed materials of M. tuberculosis (Canetti), M. kansasii, and M. gastri, whereas glycopeptidolipids were identified in the outermost lipid constituents of M. avium and M. smegmatis. This difference in the surface exposure of lipids of various mycobacterial species may reflect differences in their cell envelope organizations. Brief treatments of M. tuberculosis with Tween 80 prior to the use of glass beads led to erosion of regions of the capsule to expose gradually both cord factor and other lipids on the cell surface of the tubercle bacillus, demonstrating that the latter lipids are buried more deeply in the cell envelope and leading to the proposal of a scheme for the location of the capsular lipids of the tubercle bacillus.

A New Glycosylated Lipopeptide Incorporated into the Cell Wall of a Smooth Variant of Gordona hydrophobica

“…These long chain components are thought to intercalate with the mycolic acid layer by hydrophobic interaction resulting in the exposition of the more polar groups of the free lipids to the hydrophilic exterior. Recently, Ortalo-Magné et al (25) identified the surface-exposed lipids of several mycobacterial species. They isolated the lipids of Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium kansasii, Mycobacterium gastri, Mycobacterium smegmatis, and Mycobacterium aurum by gently treating the cells with glass beads thereby demonstrating a selective location of classes of ubiquitous lipids on the surface of mycobacteria.…”

“…Monomycolyl trehaloses and triacylglycerides were exposed in M. avium and M. smegmatis but not in other mycobacterial species studied so far. Phenolic glycolipids, dimycocerosates of phtiocerols and lipooligosaccharides were identified at the surface of M. tuberculosis (Canetti), M. kansasii, and M. gastri, whereas glycopeptidolipids were identified in the outermost layer of M. avium and M. smegmatis (25). However, a glycosylated N-acyl peptide on the cell surface of G. hydrophobica has so far not been isolated as a constituent of a cell envelope.…”

Organization of the mycobacterial cell wall: a nanoscale view

“…Although these major cell wall constituents are relatively well described, their three-dimensional distribution remains poorly understood and somewhat controversial [10,16]. In particular, while a large proportion of lipoarabinomannan (LAM) and mannosylated phosphatidyl inositol (LM and PIMs) are proposed to be anchored into the cell membrane via their lipidic portion, they are also known to be present in the outermost portion of the envelope, which allows them to interact with the immune system [23,26]. Thus, it is still unclear whether hydrophobic mycolic acids are present in the form of a continuous, outermost layer on the surface or whether hydrophilic polysaccharides, particularly LAMs, are embedded in this layer [10,11].…”

Nano-Immunodetection and Quantification of Mycobacteria in Metalworking Fluids

“…Probe sonication resulted in effective disaggregation of M. parafortuitum and M. immunogenum based on EFM and FCM quantification, giving a good linear correlation between both enumeration methods (Chang et al, 2004). It is plausible that the components in the semisynthetic MWF had prevented the 62 CHANG AND ADRIAENS mycobacterial cells from reaggregating (Calleja, 1984;Ortalo-Magné et al, 1996). Optical interference due to MWF matrices has been successfully overcome by adding low-polarity solvents (Chang et al, 2004(Chang et al, , 2005.…”

“…Traditional immunofluorescence (IF) has been applied to detect mycobacteria in clinical matrices (Ortalo-Magné et al, 1996;Yi et al, 1998) and also in metalworking fluids (Chang et al, 2005). However, it has been shown that the recovery rate in IF was relatively low (Chang et al, 2005).…”