Hemolytic and antimicrobial activities of the twenty-four individual omission analogues of melittin.
Although melittin's hemolytic activity has been extensively studied, the orientation of membrane-bound melittin remains uncertain. We have investigated the effect of individually omitted amino acid residues on melittin's activity and related these results to the existing models of melittin-membrane interaction. The extent of hemolysis of the omission analogues closely followed the four known conformational regions of melittin: omission of any of the residues making up the two alpha-helical regions decreased the hemolytic activity relative to melittin, while omission of any of the residues making up the "hinge" or the C-terminal regions had little or no effect. Our results correlate best with a proposed model in which melittin initially forms "holes" in the membrane, resulting in an initial rapid loss of hemoglobin; the membrane-bound melittin is then internalized into the membrane, resulting in a later slow phase of hemoglobin loss. It was also found that induced structural effects caused by peptide-lipid interactions could be studied by using RP-HPLC, with an excellent correlation found between the retention times of the individual omission analogues and their hemolytic activities.
Blondelle
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SE
Torrey Pines Institute for Molecular Studies, San Diego, California 92121.
Houghten
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RA
D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002851:Chromatography, High Pressure Liquid; D006461:Hemolysis / Q000187:drug effects*; D008555:Melitten / Q000235:genetics / Q000494:pharmacology*; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D011550:Pseudomonas aeruginosa / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects
D000900:Anti-Bacterial Agents; D008555:Melitten