Part:BBa_K3504003
nSP4-RNA-directed RNA Polymerase-Eastern equine encephalitis virus
Part Description
Nsp4 is one of four non structural proteins that together forms the main complex responsible for the synthesis positive-sense viral RNAs, results in the synthesis of both the genomic and subgenomic RNAs, of which the subgenomic RNA is produced in excess of the viral genome. Which allows the virus to self-replicate into millions of copies of the virus.
Usage
∼70kDa nsP4 protein : All the previous nonstructural proteins shared work in the synthesis of the RNA but the nsP4 is especially responsible for the RNA synthetic properties of the viral replicase complex. The nsP4 protein contains the core RdRp domain and motifs. Many alphavirus species produce significantly less nsP4 than the other non-structural proteins. N-terminal truncation mutants of nsP4 have demonstrated terminal adenylyltransferase (TATase) activity, indicating a potential role in polyadenylation, but were ultimately found to lack de-novo copying activity.Full-length recombinant nsP4 exhibited TATase activity and was capable of de novo RNA synthetic activity only after the addition of the other viral non-structural proteins supplied from mammalian cell membrane fractions. Despite nsP4 being the sole viral protein with RdRp activity, viral replication is the sum of coordinated non-structural protein activity. Some mutational analyses have indicated that determinants for RNA synthesis exist within nsP4. Genetic evidence suggests nsP4 has absolutely conserved N-terminal tyrosine interacts with nsP1 for minus-strand synthesis. Stollar and colleagues have determined several determinants of promoter binding in nsP4 as residues of nsP4 were found to contact the subgenomic and genomic promoters as determined by RNA cross-linking experiments.
Characterization
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12INCOMPATIBLE WITH RFC[12]Illegal NheI site found at 948
Illegal NheI site found at 1765 - 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal AgeI site found at 19
- 1000COMPATIBLE WITH RFC[1000]
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