Premium
Multivalency effects of hemagglutinin component of type B botulinum neurotoxin complex on epithelial barrier disruption
Author(s) -
Amatsu Sho,
Matsumura Takuhiro,
Yutani Masahiro,
Fujinaga Yukako
Publication year - 2018
Publication title -
microbiology and immunology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.664
H-Index - 70
eISSN - 1348-0421
pISSN - 0385-5600
DOI - 10.1111/1348-0421.12565
Subject(s) - biophysics , hemagglutinin (influenza) , trimer , cadherin , binding site , biology , cell , mutant , plasma protein binding , epithelium , biochemistry , microbiology and biotechnology , chemistry , dimer , genetics , organic chemistry , gene
Hemagglutinin (HA) is one of the components of botulinum neurotoxin (BoNT) complexes and it promotes the absorption of BoNT through the intestinal epithelium by at least two specific mechanisms: cell surface attachment by carbohydrate binding, and epithelial barrier disruption by E‐cadherin binding. It is known that HA forms a three‐arm structure, in which each of three protomers has three carbohydrate‐binding sites and one E‐cadherin‐binding site. A three‐arm form of HA is considered to bind to these ligands simultaneously. In the present study, we investigated how the multivalency effect of HA influences its barrier‐disrupting activity. We prepared type B full‐length HA (three‐arm form) and mini‐HA, which is a deletion mutant lacking the trimer‐forming domain. Size‐exclusion chromatography analysis showed that mini‐HA exists as dimers (two‐arm form) and monomers (one‐arm form), which are then separated. We examined the multivalency effect of HA on the barrier‐disrupting activity, the E‐cadherin‐binding activity, and the attachment activity to the basolateral cell surface. Our results showed that HA initially attaches to the basal surface of Caco‐2 cells by carbohydrate binding and then moves to the lateral cell surface, where the HA acts to disrupt the epithelial barrier. Our results showed that the multivalency effect of HA enhances the barrier‐disrupting activity in Caco‐2 cells. We found that basal cell surface attachment and binding ability to immobilized E‐cadherin were enhanced by the multivalency effect of HA. These results suggest that at least these two factors induced by the multivalency effect of HA cause the enhancement of the barrier‐disrupting activity.