Functional Crosstalk between Distant Domains of Chikungunya Virus Non-Structural Protein 2 Is Decisive For Its RNA-Modulating Activity [Molecular Bases of Disease]

January 9th, 2014 by Das, P. K., Merits, A., Lulla, A.

Chikungunya virus (CHIKV) non-structural protein 2 (nsP2) is a multifunctional protein that is considered as a master regulator of the viral lifecycle and a main viral factor responsible for cytopathic effects and subversion of antiviral defense. The C-terminal part of nsP2 possesses protease activity, while the N-terminal part exhibits NTPase and RNA triphosphatase activity, and is proposed to have helicase activity. Bioinformatic analysis classified CHIKV nsP2 into helicase superfamily 1 (SF1). However, the biochemical significance of a coexistence of two functionally unrelated modules in this single protein remains unknown. In this study recombinant nsP2 demonstrated the unwinding of double-stranded RNA in a 5'-3' directionally biased manner and RNA strand-annealing activity. Comparative analysis of NTPase and helicase activities of wild type nsP2 with enzymatic capabilities of different truncated or N-terminally extended variants of nsP2 revealed that the C-terminal part of protein is indispensable for helicase functionality and presumably provides platform for RNA binding, whereas the N-terminal-most region is apparently involved in obtaining conformation of nsP2 that allows for its maximal enzymatic activities. The establishment of the protocols for the production of biochemically active CHIKV nsP2 and optimization of the parameters for helicase and NTPase assays is expected to provide the starting point for further search of possibilities for therapeutic interventions to suppress alphaviral infections.
  • Posted in Journal of Biological Chemistry, Publications
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