Functional form of Caveolin-1 is necessary for the assembly of α-hemolysin

The assembly of α-HL was shown to rapidly progress upon its interaction with Caveolin-1. Treatment of A431 cells with α-HL has resulted in clustering of Caveolin-1 at cell–cell contacts. Consistent with this observation, α-HL mutants devoid of assembly property have not induced the clustering of Caveolin-1. While cholesterol depletion of A431 cells completely arrests the assembly of α-HL, chelation of membrane cholesterol results in its retarded assembly. Interestingly, HT29 cells, with low Caveolin-1 levels, are resistant to α-HL attack. Clustering of Caveolin-1, as seen in case of A431 cells, was readily observed in case of HT29 cells transfected with Caveolin-1 construct, thus overexpressing the full length Caveolin-1, upon α-HL treatment. A model was constructed to visualize the interactions between α-HL and Caveolin-1 which suggests that facile penetration of α-HL’s β-barrel might occur through protein–protein interactions with the surrounding 7 α-helices of Caveolin-1.