ANALYSIS OF HEPATITIS-C VIRUS CORE PROTEIN-INTERACTION DOMAINS

Hepatitis C virus (HCV) core protein forms the internal viral coat tha t encapsidates the genomic RNA and is enveloped in a host cell-derived lipid membrane. As the single capsid protein, core should be capable of multimerization but attempts to produce virus-like particles follow ing expression of HCV structural proteins have not been successful. In this study, we have analysed the interaction capacity of full-length and truncated HCV core using the yeast two-hybrid system. Full-length core containing or tacking the translocation signal for the El glycopr otein did not interact with full-length or truncated core proteins. Tr uncation to the N-terminal 122 aa revealed an interaction domain which was mapped to the tryptophan-rich sequence from aa 82-102 and was ter med the main homotypic interaction domain. The C-terminal hydrophobic fragment of core (aa 122-172) was incapable of interacting with itself but interacted with the main homotypic interaction domain in trans (t he weak heterotypic interaction domain). Core proteins truncated at th eir N and C termini (aa 46-102) were trans-activating when fused to th e DNA-binding domain of GAL4. Based on our results, we suggest that th e C-terminal segment may interact in cis with the main homotypic inter action domain and thereby prevent multimerization. Core-core interacti on was also observed for in vitro-translated proteins bound to truncat ed immobilized core102. However, interaction was less specific in this system suggesting that protein interaction and possibly conformationa l alteration of core may be dependent on the experimental system.