Stemloop asioita, UTRs, ebolasanastoa

 

Identification and characterization of short leader and trailer RNAs synthesized by the Ebola virus RNA polymerase

Fig 1

(A) Schematic presentation of the EBOV genome. The terminal 3’-leader and 5’-trailer regions (p, promoters) are relevant to viral RNA synthesis and encapsidation. The genome harbors 7 protein genes whose mRNA expression levels (schematically shown below the genome, terminal dots indicating the 5’-cap) decrease from the first (NP) to the last (L) mRNA. Potential secondary structures involving the 7 transcription start signals (TSS, in light blue) are depicted above the genome. White boxes indicate the coding regions for EBOV proteins (NP, VP35, VP40, GP, VP30, VP24, L) and light gray boxes 5’- and 3’-UTRs. Dark gray areas mark the position of the potential secondary structures depicted above the genome. (B) Close-up of the genomic 3’-leader promoter (top) and the complementary antigenomic sequence (bottom). The shown secondary structures form in the free RNAs as confirmed by structure probing [13,26,44]. Promoter elements (PE) 1 and 2 of the bipartite leader promoter are marked in green, with pink U residues denoting UN5 hexamers in the region between nt 51 to 128. The TSS (in cyan) and and a spacer sequence (orange residues) form the NP hairpin. Hexamer phasing in the leader promoter, manifesting as the need for a multiple of 6 nt between position 51 and 80, is crucial for EBOV replication and transcription initiation at the 3’-leader promoter [13,18,40].

https://journals.plos.org/plospathogens/article/figure?id=10.1371/journal.ppat.1010002.g001

Kirchdoerfer, R. N., Moyer, C. L., Abelson, D. M. & Saphire, E. O. The Ebola virus VP30-NP interaction is a regulator of viral RNA synthesis. PLoS Pathog. 12, e1005937 (2016).

A recent study of the Ebola viral VP30/NP concluded that this interaction is as a regulator of viral RNA synthesis23. This observation is consistent with the results reported here. Together, these studies highlight the significance of this VP30/NP interaction, and in particular, we show that this interaction, at least in part, is significant for recognition of a critical stem loop in the viral UTR. Further efforts to examine this interaction for therapeutic development are likely to result in new insights into the complex molecular mechanism of filoviral RNA synthesis.