Enlarged scale chemical synthesis and range of activity of drosocin, an O-glycosylated antibacterial peptide of Drosophila.
Insects respond to a bacterial challenge by rapidly synthesizing a diverse range of antibacterial and antifungal peptides. One of them, drosocin, a 19-residue proline-rich antibacterial peptide, was isolated from Drosophila. This peptide carries a disaccharide moiety attached to a threonine residue in mid-chain position. The present report describes the enlarged-scale chemical synthesis of drosocin, glycosylated with Gal (beta 1 --> 3)GalNAc(alpha 1 --> O). We have studied the range of activity of the synthetic glycopeptide, of two truncated glycosylated isoforms, and of the unglycosylated L and D enantiomers. Both isolated and chemically synthesized drosocins carrying the disaccharide display the same antibacterial activity. Using circular dichroic spectroscopy we demonstrated that the O-linked disaccharidic motif did not affect the backbone conformation of drosocin. The antibacterial activity of the synthetic glycopeptide was directed against gram-negative strains with the exception of the gram-positive bacteria Micrococcus luteus. Deletion of the first five N-terminal residues completely abolished the activity of drosocin. As a first approach to the study of the mode of action of drosocin, we have synthesized a non-glycosylated D enantiomer and, using this molecule, we have shown that drosocin may act on the gram-negative bacteria through a stereospecific target.
Bulet
P
P
Unité Propre du CNRS No 9022, Institut de Biologie Moléculaire et Cellulaire, Strasbourg, France.
Urge
L
L
Ohresser
S
S
Hetru
C
C
Otvos
L
L
D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004330:Drosophila / Q000737:chemistry*; D006020:Glycopeptides / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D006031:Glycosylation; D006461:Hemolysis / Q000187:drug effects; D007527:Isoenzymes / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology; D008826:Microbial Sensitivity Tests; D008969:Molecular Sequence Data
D006020:Glycopeptides; D007527:Isoenzymes; C082117:drosocin