The heterogeneous nuclear ribonucleoprotein K (hnRNP K) interacts with dengue virus core protein

Heterogeneous nuclear ribonucleoprotein K (hnRNP K), a component of hnRNP particles, is involved in several steps of gene expression regulation. Dengue (DEN) virus, a member of the Flaviviridae, is the primary cause of illnesses such as dengue fever, dengue hemorrhagic fever, and dengue shock syndrome. In mature DEN virus particles, the core protein is a structural protein that forms a nucleocapsid complex with genomic RNA. Very little of its biologic functions is known. Here, using an in vitro binding assay and coimmunoprecipitation analysis, we report a protein-protein interaction between the DEN virus core protein and hnRNP K. The C-terminal hydrophilic region of the DEN virus core protein, spanning amino acid residues 73 to 100, is required for such interaction. Results of glutathione-S transferase binding assays indicated that the core protein-hnRNP K interaction might be abolished in the presence of hnRNP K cognate nucleic acids. Furthermore, in a cotransfection experiment, the repressive effect of hnRNP K on C/EBPbeta-mediated transcription activation could be reversed by full-length DEN virus core protein but not by a truncated form containing amino acids 1-72. Our results suggest that, on DEN virus infection, the multiple functions of cellular hnRNP K may be affected by the virus core protein.