Oyster hemocytes express a proline-rich peptide displaying synergistic antimicrobial activity with a defensin.
A cDNA sequence that encodes a 61-amino acid polypeptide precursor with homologies to proline-rich antimicrobial peptides (AMPs) was identified in the oyster Crassostrea gigas. After release of a hydrophobic signal peptide, the resulting 37-amino acid peptide, Cg-Prp, is composed of an acidic region and a cationic proline-rich region. To evaluate the biological properties of Cg-Prp, multiple proline-rich peptides corresponding to putative processing of the full-length Cg-Prp were synthesized. A limited antimicrobial activity was observed for two of them, which also showed strong synergistic antimicrobial activity with Cg-Def, a defensin from C. gigas. To our knowledge, this is the first evidence of synergy between a defensin and another AMP in an invertebrate. By in situ hybridization, the expression of Cg-prp was found to be restricted to hemocytes and induced following bacterial challenge. Cg-prp transcripts were also detected in hemocytes infiltrating mantle, where Cg-Def is expressed. Additionally, by immunocytochemistry, we showed that Cg-Prp or one of its variants is present in some hemocytes together with defensins. In conclusion, we described here the first proline-rich AMP from mollusk. From our study, it is likely to provide a first line of defense against bacterial invasion by acting through synergy with defensins.
Gueguen
Yannick
Y
Ifremer, CNRS, Université de Montpellier II, UMR 5119 "Ecosystèmes Lagunaires", Place Eugène Bataillon, CC80, 34095 Montpellier Cedex 5, France. ygueguen@ifremer.fr
Bernard
Romestand
R
Julie
Fievet
F
Paulina
Schmitt
S
Delphine
Destoumieux-Garzón
DG
Franck
Vandenbulcke
V
Philippe
Bulet
B
Evelyne
Bachère
B
D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000138:chemical synthesis / Q000276:immunology / Q000378:metabolism*; D001419:Bacteria / Q000276:immunology; D001483:Base Sequence; D049896:Crassostrea / Q000276:immunology* / Q000378:metabolism; D023082:Defensins / Q000276:immunology / Q000378:metabolism*; D006434:Hemocytes / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D007113:Immunity, Innate; D008969:Molecular Sequence Data; D016415:Sequence Alignment
D023181:Antimicrobial Cationic Peptides; D023082:Defensins