Structural highlights
Function
D0U7D9_CHIKV Inactive precursor of the viral replicase, which is activated by cleavages carried out by the viral protease nsP2.[ARBA:ARBA00002589] Multifunctional protein whose N-terminus is part of the RNA polymerase complex and displays NTPase, RNA triphosphatase and helicase activities. NTPase and RNA triphosphatase are involved in viral RNA capping and helicase keeps a check on the dsRNA replication intermediates. The C-terminus harbors a protease that specifically cleaves the polyproteins and releases the mature proteins. Required for the shutoff of minus-strand RNAs synthesis. Specifically inhibits the host IFN response by promoting the nuclear export of host STAT1. Also inhibits host transcription by inducing the rapid proteasome-dependent degradation of POLR2A, a catalytic subunit of the RNAPII complex. The resulting inhibition of cellular protein synthesis serves to ensure maximal viral gene expression and to evade host immune response.[ARBA:ARBA00053271] RNA dependent RNA polymerase. Replicates genomic and antigenomic RNA by recognizing replications specific signals. The early replication complex formed by the polyprotein P123 and nsP4 synthesizes minus-strand RNAs. The late replication complex composed of fully processed nsP1-nsP4 is responsible for the production of genomic and subgenomic plus-strand RNAs.[ARBA:ARBA00060137] Seems to be essential for minus-strand RNAs and subgenomic 26S mRNAs synthesis. Displays mono-ADP-ribosylhydrolase activity. ADP-ribosylation is a post-translational modification that controls various processes of the host cell and the virus probably needs to revert it for optimal viral replication. Binds proteins of G3BP family and sequesters them into the viral RNA replication complexes thereby inhibiting the formation of host stress granules on viral mRNAs. The nsp3-G3BP complexes bind viral RNAs and probably orchestrate the assembly of viral replication complexes, thanks to the ability of G3BP family members to self-assemble and bind DNA.[ARBA:ARBA00054250] The early replication complex formed by the polyprotein P123 and nsP4 synthesizes minus-strand RNAs. As soon P123 is cleaved into mature proteins, the plus-strand RNAs synthesis begins.[ARBA:ARBA00058002]
