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Bacillus anthracis cell envelope components.
1Toxines et Pathogénie Bactériennes (URA 2172, CNRS), Institut Pasteur, 28 rue du Dr Roux, 75724, Paris, France. afouet@pasteur.fr
Current Topics in Microbiology and Immunology
|September 13, 2002
Summary
Bacillus anthracis possesses a unique cell wall structure, including a peptidoglycan layer and an S-layer composed of specific proteins. Its poly-gamma-D-glutamate capsule provides an antiphagocytic role, crucial for bacterial survival in host environments.
Area of Science:
- Microbiology
- Bacterial Cell Wall Structure
- Pathogenesis
Background:
- Bacillus anthracis is a Gram-positive bacterium.
- It has a complex cell wall structure.
- The cell wall is essential for bacterial survival and virulence.
Purpose of the Study:
- To describe the detailed architecture of the Bacillus anthracis cell wall.
- To identify the components and their organization within the cell wall.
- To elucidate the role of the poly-gamma-D-glutamate capsule in virulence.
Main Methods:
- Detailed biochemical analysis of cell wall components.
- Microscopic examination of bacterial structure.
- Investigation of capsule synthesis under specific environmental conditions.
Main Results:
- The cell wall comprises a peptidoglycan layer (A1 gamma type) and an outer S-layer.
- A unique polysaccharide is covalently linked to the peptidoglycan.
- The S-layer is formed by two proteins anchored via their SLH N-terminal domain.
- A poly-gamma-D-glutamate capsule, with an antiphagocytic role, is synthesized under host-mimicking conditions (37°C, bicarbonate).
Conclusions:
- Bacillus anthracis exhibits a highly specialized cell envelope.
- The S-layer proteins and polysaccharide layer contribute to cell wall integrity.
- The poly-gamma-D-glutamate capsule is a key virulence factor regulated by environmental cues.