Assembly and penetration of 14-strand beta-barrel of staphylococcal alpha-hemolysin (alpha-HL) is an intriguing phenomenon due to its water soluble property. alpha-HL interacts with the Caveolin-1 of A431 cells for its rapid assembly. A nine amino acid, non-hydrophobic peptide derived from alpha-HL has been shown to block the interaction of alpha-HL with the scaffolding domain of Caveolin-1. alpha-HL's presence was also detected in the Caveolin-1 enriched membrane fractions isolated by ultracentrifugation. Moreover, alpha-HL co-precipitates with Caveolin-1 specifically. In a time-dependent process, alpha-HL associates with the Caveolin-1 and co-localizes with Caveolin-1 that results in an extensive clustering of Caveolin-1 at cell-cell contacts. Mutants of alpha-HL devoid of Caveolin-1 binding motif failed to assemble into heptameric oligomers on the surface of A431 cells. Our data suggest that the conformational changes required to form the heptameric assembly might be triggered at the Caveolin-1 binding motif of alpha-HL. (C) 2004 Elsevier Inc. All rights reserved.