Molecular details of the double-stranded RNA virus replication and assembly

Forskningsoutput: AvhandlingDoktorsavhandling


Viruses are obligate parasites infecting the cells from all the three domains of life: Bacteria, Archaea and Eukarya. Ribonucleic acid (RNA) viruses contain ribonucleic acid as their genomic element instead of deoxyribonucleic acid (DNA). There are three main types of RNA viruses: positive-sense single-stranded [(+)ssRNA], negative-sense single-stranded [(-)ssRNA] and double-stranded RNA (dsRNA) viruses. This Thesis is focused on revealing molecular details of replication and assembly of two dsRNA viruses: Pseudomonas phage phi6 (phi6) and human picobirnavirus(hPBV). Double-stranded RNA viruses need to carry an RNA-dependent RNA polymerase (RdRp) inside their virion to the host in order to be able to replicate their genome. We characterized the hPBV RdRp enzymatically and structurally and revealed the similarities of this RdRp to the other known small dsRNA virus RdRps like phi6 RdRp, which has been extensively studied. We showed that hPBV RdRp has a canonical cupped right-hand polymerase structure, it can replicate and transcribe homologous and heterologous template RNA in the absence of capsid proteins and it also possesses terminal nucleotidyl transferase activity. This is only the second dsRNA virus RdRp reported with this activity. The assembly of these two viruses is relatively different due to the differences in their structures. Phi6 has three layers and a lipid-protein envelope as its outermost layer whereas hPBV does not have any lipids in its structure and is composed of only one layer of capsid proteins surrounding the dsRNA genome. The assembly of the inner protein layers of phi6 is very well-known whereas as the envelope formation and the assembly of hPBV capsid layer is largely uncharacterized. Our results suggest that hPBV might use a co-assembly of its capsid proteins and
vgenomic RNA precursors as its assembly strategy. The envelope assembly of phi6 was studied expressing phi6 membrane proteins in Escherichia colibacteria. Our results revealed that only one small membrane protein P9 can induce phi6-specific vesicle formation in E. colicells. Also, heterologous green fluorescent protein can be added to the vesicles by co-expressing non-structural P12 protein. This study reveals interesting molecular details about the genome replication and assembly of hPBV, a relatively unknown opportunistic human pathogen, and the envelopment process of phi6. These results are biologically interesting and may have also biotechnological applications in the future.
Tilldelande institution
  • Bio- och miljövetenskapliga fakulteten
  • Poranen, Minna, Handledare
Tilldelningsdatum24 sep 2019
Tryckta ISBN978-951-51-5403-3
StatusPublicerad - 6 sep 2019
MoE-publikationstypG5 Doktorsavhandling (artikel)


  • 1183 Växtbiologi, mikrobiologi, virologi

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