Chemical characterization of the ester-linked 3-hydroxy fatty acyl-containing lipids in Mycobacterium tuberculosis

Abstract

In a previous study (S. Alugupalli, F. Portaels, and L. Larsson, J. Bacteriol. 176:2962-2969, 1994), we reported the occurrence of 21 3-hydroxy fatty acids (3-OH-FAs) in the methanolysis products of different mycobacterial species. The present study was undertaken in order to chemically characterize the ester-linked complex native forms of these acids in Mycobacterium tuberculosis. Three 3-OH-FA-containing lipids were purified by chromatography and analyzed by one-and two-dimensional nuclear magnetic resonance spectroscopy, by fast atom bombardment-mass spectrometry, and by various conventional chemical analysis techniques. 3-OH-2,4,6-trimethyl-FAs were found in 2,3-diacyl trehalose and 2,3,6,6 -tetra-acyl-2 -sulfate trehalose (sulfatide I), two specific glycolipids of the tubercle bacillus, explaining the specific occurrence of these fatty acids in the methanolysis products of virulent strains of M. tuberculosis. Straight-chain 3-OH-FAs were localized in phosphatidyl ethanolamine but not in the other phospholipids, suggesting a possible role of this class of phospholipids in the metabolism of fatty acids in actinomycetes.Tuberculosis remains the leading cause of death in the world from a single pathogen (7,18). The slow growth of the tubercle bacillus and the lack of easy and reliable tests for detecting the disease at an early stage also limit the program of control and eradication of tuberculosis. In this context, recent efforts have been devoted to more knowledge of the disease and its pathogen.Most of the unique features of mycobacteria, such as their mold-like growth pattern and their resistance to chemical agents, as well as many of their biologic activities have been attributed to their high lipid content (17). Detailed chemical studies demonstrated the diversity and the complexity of the mycobacterial fatty acids, which have been used in chemotaxonomy in order to discriminate among mycobacterial species (4,8,24). These compounds include 2-alkyl branched, 3-hydroxylated long chain fatty acids (up to 90 carbon atoms), the so-called mycolic acids, multi-methyl (Me) branched-chain fatty acids having chiral centers with an L or D configuration, and ␣,␤-unsaturated compounds. We recently characterized 21 3-hydroxy fatty acids (3-OH-FAs), i.e., straight-chain and 2-Me and 2,4,6-tri-Me branched-chain fatty acids, in 27 strains belonging to 12 mycobacterial species (2). According to their 3-OH-FA patterns, the mycobacterial species could be subdivided into six groups, suggesting a taxonomic interest for these fatty acids. Virulent strains of Mycobacterium tuberculosis exhibited an unique pattern of 3-OH-FAs in that they contain multi-Me branched long chain hydroxy fatty acids, the potential precursors of fatty acids found in the biologically important mycobacterial lipids (4, 24). The present study was undertaken in order to chemically characterize the ester-linked native forms of straight-and Me branched-chain 3-OH-FAs in M. tuberculosis.M. tuberculosis H37Rv was grown for 4 weeks on Sauton's medium (26) as sur...

The Role of MmpL8 in Sulfatide Biogenesis and Virulence of Mycobacterium tuberculosis

“…The anomeric protons appear at ␦5.06 and 5.25 ppm. The doublet at ␦5.06 ppm (J ϭ 3.8 Hz) formed a cross-peak with an upfield doublet of doublets (␦3.48 ppm, J ϭ 9.8, 3.7 Hz), which corresponds to the proton adjacent to the 2Ј-sulfate, and was, therefore, assigned as the H-1Ј anomeric proton, consistent with previous descriptions (38). The H-2Ј signal was observed to be coupled to the doublet at ␦3.74 ppm (J ϭ 9.3 Hz), which was therefore assigned as the H-3Ј proton.…”

Lipids of Clinically Significant Mycobacteria

“…Ornithine lipids replace PE in reduced phosphate cultures in other bacteria (Minnikin and Abdolrahimzadeh 1974). PEs from M. tuberculosis have minor 3-OH-C 16, 18, 20 straight-chain fatty acids (Alugupalli et al 1995), similar to that in the ornithine lipids (OL) (Fig. 22).…”

“…Certain Ac 4 SGL fractions apparently contained mycolipanolates, as found in DAT-II glycolipids ( Fig. 7A) (Alugupalli et al 1995).…”

The Mycobacterium tuberculosis pks2 Gene Encodes the Synthase for the Hepta- and Octamethyl-branched Fatty Acids Required for Sulfolipid Synthesis

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