The present invention refers to a recombinant single-chain alpha-hemolysin polypeptide of Staphylococcus aureus , having a deletion in the stem domain for removing hemolytic activity, wherein at least one heterologous sequence is inserted in a region selected from the group consisting of regions defined by amino acid position 108 to 151, amino acid position 1 to 5, amino acid position 288 to 293, amino acid position 43 to 48, amino acid position 235 to 240, amino acid position 92 to 97, amino acid position 31 to 36, amino acid position 156 to 161 in respect to the wild-type sequence SEQ ID NO: 1, with the proviso that, if the heterologous sequence contains five or more consecutive histidine residues the moiety of the heterologous sequence other than the moiety represented by said five or more consecutive histidine residues has a minimum length of 11 amino acid residues； or a variant thereof, wherein in addition to said deletion in the stem domain and said insertion of heterologous sequence, 1 to 50 amino acid residues are added, substituted or deleted in respect to the wild-type sequence SEQ ID NO: 1 and has the activity to form oligomers and to bind to lipidic bilayers or cell membranes. The present invention also provides a medicament and vaccine comprising said recombinant polypeptide.
