Progress Toward Removal of the Purification Tag in a Putative Toxin Protein via Site-Specific Mutagenesis and Proteolytic Cleavage

Putative toxin protein BC_2332, isolated from Bacillus cereus, which is a relative of Bacillus anthracis, shows similarity in the active site to ADP-ribosylating proteins present in cholera and diphtheria. Preliminary attempts to measure the activity of the putative toxin were unsuccessful leading to the hypothesis that the purification tag is hindering the activity. This hypothesis is supported by crystal structure analysis showing the putative active site occupied by the purification tag. Our objective was to remove the purification tag, via two different methods, in order to relieve potential inhibition. Both methods have faced obstacles and the work is continuing