Identification and characterization of syntenin binding protein in the black tiger shrimp Penaeus monodon

Shrimp exhibit a diverse response to viral infection that is manifested in drastic up- and down-regulations of a variety of genes. In our previous work, we identified syntenin of the shrimp Penaeus monodon (Pm) as a dynamic responder to white spot syndrome virus (WSSV) infection, its message being greatly upregulated in the acute phase of the infection. In order to further explore the link between Pm-syntenin and viral infection, we performed a yeast two-hybrid screening of a P. monodon cDNA library, using Pm-syntenin as bait. One of the molecules that specifically interacted with Pm-syntenin was the receptor-binding domain of alpha-2-macroglobulin (alpha M-2). A GST pull-down assay showed that GST-alpha M-2, but not GST alone, was capable of co-precipitating syntenin. Another GST pull-down assay showed that GST-syntenin, but not GST alone, was capable of co-precipitating alpha M-2. In addition, mutant analyses showed that the N-terminal 131 amino, acids of syntenin were both necessary and sufficient to bind the C-terminus receptor-binding domain of alpha M-2. Furthermore, WSSV-infected Pm showed a significant upregulation of the alpha M-2 message, suggesting that both syntenin and its protein partner alpha M-2 are upregulated in the acute phase of a WSSV infection. Taken together with a previous report showing the co-localization of alpha M-2 and syntenin in the exosome of a dendritic cell line, it is likely that syntenin, through its interaction with alpha M-2, plays an important role in the immune defense mechanisms of viral infections of shrimps. (c) 2005 Elsevier B.V. All rights reserved.