Discovery and characterization of the Bacillus anthracis exosporium glycoprotein BcIB.

摘要

Anthrax is a fatal disease caused by the organism Bacillus anthracis. B.anthracis has both spore and vegetative forms, both of which are important in pathogenesis. The spore is involved in the initial stages of infections. It is a focal area of intrest because of its resistant properties towards environmental factors and intracellular killing, which allows subsequent germination into vegetative cells, from which toxins are released and permitted to spread in the host. A vital structure of the spore is a surface component known as the exosporium. Characterization of this layer may be the key to understanding the resilience of the spore. An enhanced view of this structure has been observed by transmission electron microscopy with an additional first time use of ruthenium red staining. Recent studies have shown that the exosporium region contains a > 250 kDa glycoprotein labeled Bc1A. The following research describes the presence of both Bc1A and another glycoprotein present in the exosporium. This observation was achieved by combining gel electrophoresis and staining techniques for isolation and separation, transfer of proteins to membranes in order to detect carbohydrate constituents, and mutational studies to determine its function. The second glycoprotein has a molecular weight of 205 kDa and was given the label Bc1B because of the presence of collagen-like repeats observed in Bc1A. Previous studies utilizing gas chromatography-mass spectrometry (GC-MS) in this laboratory have demonstrated the presence of rhamnose, 3-O-methyl rhamnose, and galactosamine in whole spores. This technique along with gas chromatography-tandem mass spectrometry was used to confirm that these spore-specific carbohydrates are also components of Bc1A as well as Bc1B. For identification purposes, its gene was successfully removed and revealed that this glycoprotein is greatly involved in maintaining the exosporium structure by serving as a linker for Bc1A attachment in the exosporium. It also helps maintain the permeability barrier against outer interfering agents. This glycoprotein may be useful as a biomarker for B. anthracis, or used as a target or additional component to the current vaccine treatment method.