Structural identification by mass spectrometry of a novel antimicrobial peptide from the venom of the solitary bee Osmia rufa (Hymenoptera: Megachilidae)

• Published in: Toxicon (Oxford) 2010, Vol.55 (1), p.20-27
• Main Authors: Stöcklin, Reto, Favreau, Philippe, Thai, Robert, Pflugfelder, Jochen, Bulet, Philippe, Mebs, Dietrich
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Analytical chemistry; Animal poisons toxicology. Antivenoms; Animals; Anti-Infective Agents - chemical synthesis; Anti-Infective Agents - chemistry; Antibacterial; Antifungal; Antifungal Agents - chemical synthesis; Antifungal Agents - chemistry; Antimicrobial Cationic Peptides - chemical synthesis; Antimicrobial Cationic Peptides - chemistry; Bee; Bee Venoms - chemical synthesis; Bee Venoms - chemistry; Bee Venoms - isolation & purification; Bees - anatomy & histology; Bees - chemistry; Bees - ultrastructure; Biochemistry; Biochemistry, Molecular Biology; Biological and medical sciences; Chemical Sciences; Chromatography, High Pressure Liquid; Circular Dichroism; ESI-MS; Fungi - drug effects; Gram-Negative Bacteria - drug effects; Gram-Positive Bacteria - drug effects; Haemolysis; Hemolysis - drug effects; Insect Proteins - chemistry; LC–MS; Life Sciences; Mass spectrometry; Medical sciences; Medication; Microbial Sensitivity Tests; Models, Molecular; Molecular Sequence Data; MS/MS; Osmia rufa; Peptides - chemical synthesis; Peptides - chemistry; Pharmaceutical sciences; Proteomics; Radiochemistry; Sequence Alignment; Spectrometry, Mass, Electrospray Ionization; Structural Biology; Tandem Mass Spectrometry - methods; Toxicology; Venom
• ISSN: 0041-0101; 1879-3150; 0041-0101
• DOI: 10.1016/j.toxicon.2008.12.011

The venom from the solitary bee Osmia rufa (Hymenoptera: Megachilidae) was analyzed using mass spectrometry (MS)-based techniques. Sensitive proteomic methods such as on-line LC–ESI-MS and nanoESI-MS analyses revealed more than 50 different compounds with molecular masses ranging from 400 to 4000 Da. The major component has a monoisotopic molecular mass of 1924.20 Da and its amino acid sequence was elucidated by de novo sequencing using tandem mass spectrometry and Edman degradation. This 17-residue cysteine-free peptide, named osmin, shows some similarities with the mast cell degranulation (MCD) peptide family. Free acid and C-terminally amidated osmins were chemically synthesized and tested for antimicrobial and haemolytic activities. The synthetic C-amidated peptide (native osmin) was found to be about three times more haemolytic than its free acid counterpart, but both peptides are much less lytic than melittin from social bee venom. Preliminary antimicrobial and antifungal tests indicate that both peptides are able to inhibit bacterial and fungal growth at micromolar concentrations.