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Analysis of the genes encoding the antigen 85 complex and MPT51 from Mycobacterium avium
N Ohara1, N Ohara-Wada, H Kitaura
1Nagasaki University School of Dentistry, Nagasaki City, Japan. f0202@cc.nagasaki-u.ac.jp
Abstract:
The components of the fibronectin-binding antigen 85 complex (85A, 85B, and 85C) and the related protein MPB/MPT51 are major secreted proteins in Mycobacterium tuberculosis and Mycobacterium bovis BCG. The fbpA, fbpC, and mpt51 genes encoding 85A, 85C, and MPT51, respectively, were isolated from Mycobacterium avium and sequenced in this study. The structures of these genes, and that of the fbpB gene encoding the 85B protein, were conserved in these three species. The secreted amounts of 85A, 85B, 85C, and MPB/MPT51 were compared for M. tuberculosis, BCG, and M. avium. These four proteins were found in large amounts in the culture filtrates from M. tuberculosis and BCG. In contrast, in the culture filtrate from M. avium, 85B and MPT51 were abundant whereas 85A and 85C were hardly found, in spite of the presence of the encoding genes. The difference in the secretion amounts might be regulated at the transcription level. These facts might reflect host immunopathogenesis, the protective immunities against infections, and the drug susceptibilities of these organisms.
Insights
Mycobacterium avium secretes less fibronectin-binding antigen 85 complex (85A, 85C) proteins compared to M. tuberculosis and BCG, despite having the genes. This difference in secretion may impact host immunity and drug susceptibility.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- Fibronectin-binding antigen 85 complex (85A, 85B, 85C) and MPT51 are key secreted proteins in Mycobacterium tuberculosis and bovis BCG.
- These proteins play roles in host-pathogen interactions and immune responses.
Purpose of the Study:
- To investigate the presence and secretion of antigen 85 complex components and MPT51 in Mycobacterium avium.
- To compare the secretion levels of these proteins across M. tuberculosis, BCG, and M. avium.
Main Methods:
- Isolation and sequencing of fbpA, fbpC, and mpt51 genes from Mycobacterium avium.
- Comparative analysis of secreted protein amounts in culture filtrates of M. tuberculosis, BCG, and M. avium.
Main Results:
- The genes encoding antigen 85A, 85C, and MPT51 are present and conserved in M. avium, similar to M. tuberculosis and BCG.
- M. tuberculosis and BCG secreted large amounts of 85A, 85B, 85C, and MPT51.
- M. avium secreted abundant 85B and MPT51, but very low levels of 85A and 85C, despite gene presence.
Conclusions:
- Differential secretion of antigen 85 complex components and MPT51 by M. avium, compared to M. tuberculosis and BCG, is observed.
- The regulation of secretion differences may occur at the transcriptional level.
- These secretion variations could influence host immunopathogenesis, protective immunity, and drug susceptibility.
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