title: Cloning and molecular characterization of the B subunit of Escherichia coli heat-labile enterotoxin.
abstract: We have constructed a plasmid containing the gene for production of the B subunit of the heat-labile enterotoxin (LT-B) from a human isolate of Escherichia coli, strain H10407. The 0.8-kilobase gene fragment encoding synthesis of LT-B was cloned onto plasmid pBR322 after sequential digestion of the enterotoxin plasmid of strain H10407 with restriction endonucleases PstI and HindIII. LT-B was isolated by agarose affinity chromatography from cell lysates of recombinant clones expressing the B subunit. The B subunit was isolated in its oligomeric form, was structurally identical to native B subunit when examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, dissociated to monomeric B in the presence of 5 M guanidine, was immunologically identical to native B subunit in an enzyme-linked immunosorbent assay, and contained no demonstrable A subunit in any of the assays.
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology; D000918:Antibody Specificity; D001427:Bacterial Toxins; D003001:Cloning, Molecular; D004768:Enterotoxins / Q000235:genetics* / Q000276:immunology; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; D010957:Plasmids
chemical_list: D000907:Antibodies, Bacterial; D001427:Bacterial Toxins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D046911:Macromolecular Substances; C027538:heat-labile enterotoxin, E coli