Illustration of a genetically-engineered form of the bacterial alpha-hemolysin (alphaHL) toxin complexed with beta-cyclodextrin. This toxin is secreted by the bacterium Staphylococcus aureus. It is an example of a pore-forming toxin, forming pores in the membranes of affected cells, damaging or killing them (making it a cytolytic protein). The cone-shaped beta-cyclodextrin molecule is bound within the alphaHL pore. The engineered form of alphaHL binds beta-cyclodextrin more tightly than the wildtype protein. Such complexes could have a number of applications, including as biosensors, in ultrarapid DNA sequencing and in the construction of nanodevices.