Patent ID: 8545853

Claim:
A recombinant single-chain alpha-hemolysin polypeptide of Staphylococcus aureus comprising a deletion in the stem domain of the wild-type sequence of SEQ ID NO: 1 that removes hemolytic activity of the polypeptide, wherein at least one heterologous sequence is inserted in a region selected from the group consisting of regions defined by amino acid positions 108 to 151, amino acid positions 1 to 5, amino acid positions 288 to 293, amino acid positions 43 to 48, amino acid positions 235 to 240, amino acid positions 92 to 97, amino acid positions 31 to 36, and amino acid positions 156 to 161, each of SEQ ID NO: 1, with the proviso that, if the at least one heterologous sequence contains five or more consecutive histidine residues, a moiety of the at least one heterologous sequence other than a moiety comprising said five or more consecutive histidine residues, has a minimum length of 11 amino acid residues; or an isolated variant polypeptide thereof, wherein in addition to said deletion in the stem domain and said insertion of the at least one heterologous sequence, 1 to 15 amino acid residues are added, or 1 to 15 amino acid residues in the SEQ ID NO: 1 are substituted or deleted and wherein the variant polypeptide has the activity to form oligomers and to bind to lipidic mono layers and lipidic bilayers, or cell membranes.