Schistosoma mansoni dermaseptin-like peptide: structural and functional characterization.
Analysis of the Schistosoma mansoni peptidome for immunomodulatory molecules by solvent extraction and reverse-phase HPLC revealed a 27-amino-acid residue peptide from an extract of cercariae. Using matrix-assisted, laser desorption-ionization, time-of-flight mass spectrometry, the peptide yielded a protonated molecular ion [M + H]+ of m/z 2789. The unequivocal sequence was deduced by automated Edman degradation as: DLWNSIKDMAAAAGRAALNAVTGMVNQ. The peptide exhibited an 80.76% identity with dermaseptin 3.1 from the leaf frog Agalychnis annae, and was therefore named Schistosoma mansoni dermaseptin-like peptide (SmDLP). Immunocytochemical staining using a primary antidermaseptin B2 antibody located SmDLP in acetabular glands of cercariae, in and around schistosomula, and in adult worms and their eggs. Dot-blotting confirmed its presence in extracts (cercariae and worms) and excretion/secretion (E/S) products (transforming cercariae and eggs). This was corroborated by use of a MALDI-ToF spectra database of E/S products from cercariae. Functional characterization of the peptide indicated that SmDLP had typical amphipathic antimicrobial peptide properties, i.e., the ability to lyse human erythrocytes causing a decrease in the levels of nitric oxide produced by monocytic cells. This last function strongly suggests that SmDLP plays a vital role in the parasite's immunoevasion strategy. The possibility that schistosomes acquired this gene from amphibians has been discussed by constructing a phylogenetic tree.
Department of Biomedical Sciences, University of Ulster, Coleraine, Northern Ireland.
Gerry A P
GA
Quinn
Raymond
R
Heymans
Franchesca
F
Rondaj
Chris
C
Shaw
Marijke
M
de Jong-Brink
D000595:Amino Acid Sequence; D029845:Amphibian Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000737:chemistry* / Q000302:isolation & purification / Q000502:physiology; D001700:Biomphalaria; D002851:Chromatography, High Pressure Liquid; D016384:Consensus Sequence; D017124:Conserved Sequence; D015801:Helminth Proteins / Q000737:chemistry* / Q000502:physiology; D006461:Hemolysis; D057927:Hydrophobic and Hydrophilic Interactions; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D012550:Schistosoma mansoni / Q000737:chemistry* / Q000276:immunology; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013329:Structure-Activity Relationship
D029845:Amphibian Proteins; D023181:Antimicrobial Cationic Peptides; D015801:Helminth Proteins; C070905:dermaseptin