First description of French V. tubiashii strains pathogenic to mollusk: II. Characterization of properties of the proteolytic fraction of extracellular products

• Published in: Journal of Invertebrate Pathology
• Main Authors: Mersni Achour, Rachida, Imbert-Auvray, Nathalie, Huet, Valerie, Ben Cheick, Yosra, Faury, Nicole, Doghri, Ibtissem, Rouatbi, Sonia, Bordenave, Stéphanie, Travers, Marie-Agnes, Saulnier, Denis, Fruitier-Arnaudin, Ingrid
• Other Authors: Unité Santé, Génétique et Microbiologie des Mollusques (SGMM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), Ecosystèmes Insulaires Océaniens (UMR 241) (EIO), Institut de Recherche pour le Développement (IRD)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de la Polynésie Française (UPF)-Institut Louis Malardé Papeete (ILM), Institut de Recherche pour le Développement (IRD)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2014
• Subjects: [SDV]Life Sciences [q-bio]; Pacific; Crassostrea gigas; Pacific oyster
• Online Access: https://hal.science/hal-04499654; https://doi.org/10.1016/j.jip.2014.09.006

Extracellular products (ECPs) of the French V. tubiashii strain 07/118 T2 were previously reported to be toxic for the Pacific oyster Crassostrea gigas. In this study we now assessed host cellular immune responses and bacterial potential effectors by which these ECPs can be associated with host damages. The adhesion capacity (28% inhibition) and phagocytosis ability (56% inhibition) of oyster hemocytes were the main functions affected following in vitro contact between hemocytes and V. tubiashii ECPs. This may be linked to the demonstration of the capability of ECPs to cleave various cellular substrates as oyster collagen. Moreover, a strong metalloproteolytic activity was recorded with general (azocasein) and specific (ADAM) substrates and characterized by the use of standard inhibitors and metal ions. The addition of 1, 10-phenanthroline and Zn2+ decreased proteolytic activity by about 80% and 50% respectively, confirming the presence of zinc metalloproteolytic activity in the ECPs. Mass spectrometry analyses of crude ECPs identified an extracellular zinc metalloprotease encoded by a gene with an open reading frame of 1821 bp (606 aa). Consensus zinc-binding motifs specific to thermolysin family and some glycosylation and phosphorylation sites were located on the deduced protein sequence. Even if taken together, our results let us wonder if this (these) zinc metalloprotease(s) could be involved in the impairment of hemocyte immunological functions, the direct implication of this (these) protein(s) in ECPs toxicity still has to be demonstrated.