title: Synthesis of a precursor to the B subunit of heat-labile enterotoxin in Escherichia coli.
abstract: Escherichia coli K-12 minicells were employed to investigate the biosynthesis of plasmid-encoded, heat-labile enterotoxin of E. coli. Two polypeptide species related to the B subunit of the toxin were expressed in the minicells. One of these polypeptides (molecular weight, 11,500) was immunoprecipitated by antiserum to cholera toxin. Because the B subunits of heat-labile enterotoxin and cholera toxin have common antigenic sites, we concluded that this species was the mature B subunit. The larger polypeptide (molecular weight, 13,000) is likely to be a precursor of the B subunit because it could be chased into the mature form. This conversion was inhibited by compounds which dissipate proton motive force, suggesting that processing requires energy.
mesh_terms: D001427:Bacterial Toxins; D004734:Energy Metabolism; D004768:Enterotoxins / Q000032:analysis / Q000096:biosynthesis*; D004926:Escherichia coli / Q000378:metabolism*; D029968:Escherichia coli Proteins; D010957:Plasmids; D011498:Protein Precursors / Q000096:biosynthesis; D011522:Protons
chemical_list: D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D011498:Protein Precursors; D011522:Protons; C027538:heat-labile enterotoxin, E coli