Structure of partially-activated E. coli heat-labile enterotoxin (LT) at 2.6 Å resolution

摘要: Biological toxicity of E. coli heat-labile enterotoxin and the closely related cholera toxin requires that assembled be activated by proteolytic cleavage A subunit reduction a disulfide bond internal to subunit. The structural role served this is not known, however. We have crystallographically determined structure AB5 hexamer in which has been cleaved trypsin between residues 192 195. thus partially activated, it but reduced. substantially same as previously observed for uncleaved structure, suggesting although such required biological activity does itself cause conformational change.