Identification of the homotypic interaction domain of the core protein of dengue virus type 2.

Dengue virus causes dengue haemorrhagic fever or dengue shock syndrome with a high mortality rate. The genome of dengue virus is a positive-sense, single-stranded RNA encoding three structural and seven non-structural proteins. The core protein is one of the three structural proteins and is the building block of the nucleocapsid of dengue virus. The core protein of dengue virus type 2 (DEN2) is composed of 100 aa with four alpha-helix domains. An internal hydrophobic domain located at aa 44-60 was identified. The DEN2 core protein was shown to form homodimers. Deletion of aa 1-36 or 73-100 decreased but did not completely abolish the core-to-core homotypic interaction, whereas deletion of a portion (aa 44-60) within aa 37-72 completely abolished the ability of the DEN2 core proteins to interact with each other. A recombinant DEN2 core protein corresponding to aa 37-72 was able to undergo homotypic interaction and bound to a native DEN2 core protein. The results of this study indicated that the homotypic interaction domain of the DEN2 core protein is located at aa 37-72 and that the internal hydrophobic domain located at aa 44-60 plays a pivotal role in core-to-core homotypic interaction.