Bacillus anthracis spore exosporium protein BclA (BclA)

Bacillus anthracis spore exosporium protein BclA is the immunodominant surface glycoprotein located on the outermost layer, or exosporium, of the anthrax spore (UniProt P0A3E2). It consists of a collagen-like internal region with GXY repeats and is heavily glycosylated with a unique tetrasaccharide ending in the sugar anthrose, which is highly specific to B. anthracis (Daubenspeck et al., 2004, J. Biol. Chem.). BclA functions as a structural component that forms a "hair-like" nap, mediating the interaction between the spore and host immune cells, such as macrophages, during the early stages of infection (Boydston et al., 2005, Gene). Due to its surface exposure and species specificity, BclA and its associated glycans are primary targets for the development of vaccines, monoclonal antibodies, and rapid diagnostic assays (Steichen et al., 2003, J. Bacteriol.). Therapeutic approaches targeting BclA aim to enhance opsonization and clearance of spores by the host immune system, thereby preventing the progression of anthrax (Sylvestre et al., 2002, Mol. Microbiol.). The protein's unique glycosylation pattern, particularly the presence of anthrose, provides a distinct molecular signature used for differentiating B. anthracis from other closely related Bacillus species (Tamborrini et al., 2006, Angew. Chem. Int. Ed.). Research into BclA-based therapies continues to focus on synthetic carbohydrate vaccines that mimic the anthrose-containing glycans to elicit a robust immune response (Wang et al., 2007, ACS Chem. Biol.).

Other names

Bacillus collagen-like protein AExosporium protein BclABclA glycoproteinAnthrose-containing glycoprotein

Induction of protective immunity and opsonophagocytosis by targeting the exosporium surface to prevent spore germination and host cell entry.