Functional and chemical characterization of Hymenoptaecin, an antibacterial polypeptide that is infection-inducible in the honeybee (Apis mellifera).
As part of our ongoing search for novel antimicrobial agents and their use in singular or combined drug therapy, we have isolated a series of polypeptides from the lymph fluid of honeybees. These polypeptides are synthesized de novo, following experimental infection of the insect with live Escherichia coli cells, and confer a broad-spectrum antibacterial defense to the host. We have dissected this humoral "immune" system into its constituent components. In addition to the previously characterized apidaecins and abaecin, we also isolated a member of the defensin family of peptide antibiotics and, now, a novel 93-amino acid long, cationic polypeptide, termed hymenoptaecin. Detailed analysis established the complete chemical structure, including a 2-pyrrolidone-5-carboxylic acid at the N terminus, and indicated major differences with all known antibacterial polypeptides. Under physiological conditions, it inhibits viability of Gram-negative and Gram-positive bacteria, including several human pathogens. Lethal effects against E. coli are secondary to sequential permeabilization of outer and inner membrane. In combination, the six-constituent "peptide antibiotics" of bee lymph provide wide-spectrum antibacterial protection in vitro by virtue of complementarity rather than synergism.
Casteels
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Molecular Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York 10021.
Ampe
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C
Jacobs
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Tempst
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P
D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000737:chemistry / Q000302:isolation & purification / Q000494:pharmacology*; D023181:Antimicrobial Cationic Peptides; D001419:Bacteria / Q000187:drug effects; D001516:Bees / Q000737:chemistry* / Q000276:immunology; D002463:Cell Membrane Permeability; D002851:Chromatography, High Pressure Liquid; D004357:Drug Synergism; D006801:Humans; D019476:Insect Proteins; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D017386:Sequence Homology, Amino Acid
D000900:Anti-Bacterial Agents; D023181:Antimicrobial Cationic Peptides; D019476:Insect Proteins; D010455:Peptides; C080586:hymenoptaecin protein, Apis mellifera