Protein–protein interactions among the structural proteins of Chilo iridescent virus

Abstract

Chilo iridescent virus (CIV), officially named invertebrate iridescent virus 6 (IIV6), is a nucleocytoplasmic virus with a ~212-kb linear dsDNA genome that encodes 215 putative open reading frames (ORFs). Proteomic analysis has revealed that the CIV virion consists of 54 virally encoded proteins. In this study, we identified the interactions between the structural proteins using the yeast two-hybrid system. We cloned 47 structural genes into both bait and prey vectors, and then analysed the interactions in Saccharomyces cerevisiae strain AH109. A total of 159 protein-protein interactions were detected between the CIV structural proteins. Only ORF 179R showed a self-association. Four structural proteins that have homologues in iridoviruses (118L, 142R, 274L and 295L) showed indirect interactions with each other. Seven proteins (138R, 142R, 361L, 378R, 395R, 415R and 453R) interacted with the major capsid protein 274L. The putative membrane protein 118L, a homologue of the frog virus 3/Ranagrylio virus 53R protein, showed direct interactions with nine other proteins (117L, 229L, 307L, 355R, 366R, 374R, 378R, 415R and 422L). The interaction between 118L and 415R was confirmed by a GST pull-down assay. These data indicate that 415R is a potential matrix protein connecting the envelope protein 118L with the major capsid protein 274L.

Identification of virion-associated transcriptional transactivator (VATT) of SGIV ICP46 promoter and their binding site on promoter

“…Iridovirus MCP has been proved to be essential for virus replication by siRNA-based knockdown and anti-MCP serum-based neutralization test [34]. A homologue of SGIV VP57, CIV 295 L, is predicted to bind the viral DNA or DNA-binding proteins, has a function in the viral DNA replication or virus gene transcription [35]. Both SGIV VP57 and CIV 295 L have a predicted nuclear localization signal.…”

“…Co-transfection and luciferase reporter assays showed that the transient expression of four VATTs alone or combined did not significantly affect the activity of the SGIV ICP46 promoter without SGIV infection. The virion protein composition of five iridoviruses have been determined, including SGIV [32, 33, 36–38], these studies showed that iridovirus virions contain 40 to 64 virion-associated proteins and the protein-protein interactions between virion-associated proteins are required for viral assembly and other important functions throughout the course of infection [35]. It reasonable to infer that not only the presence of four VATTs but also the protein-protein interactions and structural connection existing among VATTs were needed for the transactivation of SGIV ICP46.…”

“…It reasonable to infer that not only the presence of four VATTs but also the protein-protein interactions and structural connection existing among VATTs were needed for the transactivation of SGIV ICP46. The CIV interactome study have identified the interactions between virus structural proteins using the yeast two-hybrid system, and revealed that proteins 274 L and 295 L show indirect interactions with each other and protein 274 L is interacting with proteins encoded by seven different ORFs [35]. Interestingly, SGIV VP57 and SGIV MCP are just the homologues of CIV proteins 295 L and 274 L, respectively.…”

Interaction between Two Iridovirus Core Proteins and Their Effects on Ranavirus (RGV) Replication in Cells from Different Species

“…Different approaches, such as co-immunoprecipitation (co-IP) assays [12], fluorescence microscopy, and yeast two hybrid (Y2H), have been widely used in the investigation of protein–protein relationships or interactions [13]. Recently, the Y2H assay was used to analyze protein–protein interactions among the structural proteins of Chilo iridescent virus, a member of genus Iridovirus [14].…”