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Updated: May 23, 2026
Analysis of the Lipid Composition of Mycobacteria by Thin Layer Chromatography
Published on: April 16, 2021
Identification of valine- or leucine-containing glycopeptidolipids from Mycobacterium avium-intracellulare complex
Naoya Ichimura1, Takeshi Kasama
1Graduate School of Health Care Sciences, Tokyo Medical and Dental University, 1,2,3 Yushima 1-5-45, Bunkyo-Ku, Tokyo 113-8519, Japan.
Abstract:
Mycobacterium avium-intracellulare complex is a species of acid-fast microorganisms that cause opportunistic infections in immuno-compromised hosts. The cell wall of this microbe is rich in glycopeptidolipids (GPLs), which are composed of a fatty acyl moiety, several sugar moieties and a tripeptide-amino alcohol, D-Phe-D-alloThr-D-Ala-L-Alaninol. GPLs have molecular diversity in the hydrocarbon chain variety of the acyl moiety, and methyl and acetyl modifications of the sugar moiety, but there has been no report of any variety in the tripeptide-amino alcohol component. In this study, we showed two atypical GPL ions of 34 or 48 Da less than the dominant ions of GPLs by mass spectrometry. These ions could not be explained as resulting from conventional molecular diversity. To investigate the reasons why these ions appeared, we made a preparation of the lipopeptide component from intact GPLs and structurally analyzed the molecules. The results suggested that these atypical ions differed from the typical ions in amino acid composition. We further determined its composition by amino acid analysis, and the results showed that the tripeptide portion of the two atypical ions is composed of the Val-alloThr-Ala or the Leu-alloThr-Ala amino acid sequence. In this study, we present novel variations in the tripeptide portion of GPL molecules.
Insights
Mycobacterium avium-intracellulare complex (MAC) infections are linked to atypical glycopeptidolipids (GPLs). This study reveals novel variations in the tripeptide component of MAC GPLs, expanding our understanding of microbial molecular diversity.
Area of Science:
- Microbiology
- Biochemistry
- Immunology
Background:
- Mycobacterium avium-intracellulare complex (MAC) causes opportunistic infections, particularly in immunocompromised individuals.
- The cell wall of MAC is characterized by glycopeptidolipids (GPLs), known for their molecular diversity in acyl and sugar moieties.
- Previous research had not reported variations in the tripeptide-amino alcohol component of GPLs.
Purpose of the Study:
- To investigate the origin of atypical glycopeptidolipid (GPL) ions observed in Mycobacterium avium-intracellulare complex.
- To characterize the structural and compositional differences of these atypical GPLs compared to typical ones.
Main Methods:
- Mass spectrometry was employed to detect and analyze atypical GPL ions.
- Preparation of the lipopeptide component from intact GPLs for structural analysis.
- Amino acid analysis was performed to determine the precise composition of the tripeptide portion.
Main Results:
- Two atypical GPL ions, differing by 34 or 48 Da from dominant ions, were identified.
- Structural analysis indicated differences in amino acid composition compared to typical GPLs.
- Amino acid analysis confirmed novel tripeptide sequences: Val-alloThr-Ala and Leu-alloThr-Ala.
Conclusions:
- The study presents the first evidence of variations in the tripeptide-amino alcohol component of Mycobacterium avium-intracellulare complex GPLs.
- These findings reveal a previously unrecognized source of molecular diversity within MAC GPLs.
- This discovery contributes to a deeper understanding of MAC pathogenesis and potential diagnostic markers.
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