title: The C-terminal region of the S component of staphylococcal leukocidin is essential for the biological activity of the toxin.
abstract: The Staphylococcal toxin leukocidin consists of two protein components, F and S. From a culture medium of Staphylococcus aureus RIMD 310925, we isolated a truncated form of S (LS2), of which the C-terminal 17-residue segment is missing. Unlike intact S, LS2, showed neither leukocytolytic activity in the presence of F nor affinity for monosialoganglioside GM1 (GM1). When excited at 280 nm, both S and LS2 exhibited intrinsic tryptophan fluorescence with an emission maximum at 318 nm. Upon binding to GM1, the emission maximum of S underwent a blue shift to 310 nm, whereas no change in fluorescence took place on mixing GM1 with LS2. We conclude that the C-terminal region of S is essential for its biological activity as well as for its binding to GM1 and that this binding is accompanied by a conformational change of the S protein.
authors.affiliation: Department of Applied Biological Chemistry, Faculty of Agriculture, Tohoku University, Sendai, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Nariya
authors.forename: K
authors.initials: K
authors.lastname: Izaki
authors.forename: Y
authors.initials: Y
authors.lastname: Kamio
mesh_terms: D000595:Amino Acid Sequence; D002850:Chromatography, Gel; D003470:Culture Media; D005677:G(M1) Ganglioside / Q000378:metabolism; D007956:Leukocidins / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D013050:Spectrometry, Fluorescence; D013211:Staphylococcus aureus / Q000378:metabolism*; D013329:Structure-Activity Relationship
chemical_list: D003470:Culture Media; D007956:Leukocidins; D010446:Peptide Fragments; D005677:G(M1) Ganglioside