Functional Diversification of Oyster Big Defensins Generates Antimicrobial Specificity and Synergy against Members of the Microbiota

• Published in: Marine drugs Vol. 20; no. 12; p. 745
• Main Authors: De San Nicolas, Noémie, Asokan, Aromal, Rosa, Rafael D, Voisin, Sébastien N, Travers, Marie-Agnès, Rocha, Gustavo, Dantan, Luc, Dorant, Yann, Mitta, Guillaume, Petton, Bruno, Charrière, Guillaume M, Escoubas, Jean-Michel, Boulo, Viviane, Pouzadoux, Juliette, Meudal, Hervé, Loth, Karine, Aucagne, Vincent, Delmas, Agnès F, Bulet, Philippe, Montagnani, Caroline, Destoumieux-Garzón, Delphine
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 26.11.2022; MDPI
• Subjects: Amino acid sequence; Analysis; Animal biology; Animals; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - pharmacology; Antibacterial activity; Antibacterial agents; antibacterial peptide; Antibiotics; Antimicrobial agents; Antimicrobial peptides; Bacteremia; Bacteria; Bacteria - metabolism; beta defensin; Biotyping; Chemical synthesis; Cloning; Composition; Crassostrea; Defensins; Defensins - pharmacology; Disease resistance; Diversification; diversity; evolution; Genetic aspects; Health aspects; Homeostasis; Identification and classification; Immune system; Immunology; Innate immunity; invertebrate; Invertebrate Zoology; Life Sciences; Marine molluscs; Microbial activity; microbiome; Microbiota; Microbiota (Symbiotic organisms); Microorganisms; Mollusks; Mortality; Nucleotide sequence; Oysters; Peptide synthesis; Peptides; Production processes; Protein synthesis; Sodium chloride; Solid phases; Specificity; Spectra; Synthetic peptides; Veterinary medicine and animal Health; France; diversity; antibacterial peptide; beta defensin; evolution; invertebrate; microbiome; mollusk
• ISSN: 1660-3397; 1660-3397
• DOI: 10.3390/md20120745

Big defensins are two-domain antimicrobial peptides (AMPs) that have highly diversified in mollusks. -BigDefs are expressed by immune cells in the oyster , and their expression is dampened during the Pacific Oyster Mortality Syndrome (POMS), which evolves toward fatal bacteremia. We evaluated whether -BigDefs contribute to the control of oyster-associated microbial communities. Two -BigDefs that are representative of molecular diversity within the peptide family, namely -BigDef1 and -BigDef5, were characterized by gene cloning and synthesized by solid-phase peptide synthesis and native chemical ligation. Synthetic peptides were tested for antibacterial activity against a collection of culturable bacteria belonging to the oyster microbiota, characterized by 16S sequencing and MALDI Biotyping. We first tested the potential of -BigDefs to control the oyster microbiota by injecting synthetic -BigDef1 into oyster tissues and analyzing microbiota dynamics over 24 h by 16S metabarcoding. -BigDef1 induced a significant shift in oyster microbiota β-diversity after 6 h and 24 h, prompting us to investigate antimicrobial activities in vitro against members of the oyster microbiota. Both -BigDef1 and -BigDef5 were active at a high salt concentration (400 mM NaCl) and showed broad spectra of activity against bacteria associated with pathologies. Antimicrobial specificity was observed for both molecules at an intra- and inter-genera level. Remarkably, antimicrobial spectra of -BigDef1 and -BigDef5 were complementary, and peptides acted synergistically. Overall, we found that primary sequence diversification of -BigDefs has generated specificity and synergy and extended the spectrum of activity of this peptide family.