The Crystal Structure of the Bacillus anthracis Spore Surface Protein BclA Shows Remarkable Similarity to Mammalian Proteins

• Published in: The Journal of biological chemistry 2005-12, Vol.280 (52), p.43073-43078
• Main Authors: Réty, Stéphane, Salamitou, Sylvie, Garcia-Verdugo, Ignacio, Hulmes, David J.S., Le Hégarat, Françoise, Chaby, Richard, Lewit-Bentley, Anita
• Format: Article
• Language: English
• Subjects: Animals; Bacillus anthracis; Bacillus anthracis - metabolism; Cellular Biology; Circular Dichroism; Complement C1q; Complement C1q - chemistry; Crystallography, X-Ray; Dose-Response Relationship, Drug; Humans; Life Sciences; Membrane Glycoproteins; Membrane Glycoproteins - chemistry; Models, Molecular; Protein Binding; Protein Conformation; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Proteins; Recombinant Proteins - chemistry; Surface Properties; Surface-Active Agents; Surface-Active Agents - chemistry; Temperature; Tumor Necrosis Factor-alpha; Tumor Necrosis Factor-alpha - chemistry; Ultraviolet Rays
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M510087200

The lethal disease anthrax is propagated by spores of Bacillus anthracis, which can penetrate into the mammalian host by inhalation, causing a rapid progression of the disease and a mostly fatal outcome. We have solved the three-dimensional structure of the major surface protein BclA on B. anthracis spores. Surprisingly, the structure resembles C1q, the first component of complement, despite there being no sequence homology. Although most assays for C1q-like activity, including binding to C1q receptors, suggest that BclA does not mimic C1q, we show that BclA, as well as C1q, interacts with components of the lung alveolar surfactant layer. Thus, to better recognize and invade its hosts, this pathogenic soil bacterium may have evolved a surface protein whose structure is strikingly close to a mammalian protein.