Genome activation by raspberry bushy dwarf virus coat protein

Abstract

Two sets of infectious cDNA clones of raspberry bushy dwarf virus (RBDV) have been constructed, enabling either the synthesis of infectious RNA transcripts or the delivery of infectious binary plasmid DNA by infiltration of Agrobacterium tumefaciens. In whole plants and in protoplasts, inoculation of RBDV RNA1 and RNA2 transcripts led to a low level of infection, which was greatly increased by the addition of RNA3, a subgenomic RNA coding for the RBDV coat protein (CP). Agroinfiltration of RNA1 and RNA2 constructs did not produce a detectable infection but, again, inclusion of a construct encoding the CP led to high levels of infection. Thus, RBDV replication is greatly stimulated by the presence of the CP, a mechanism that also operates with ilarviruses and alfalfa mosaic virus, where it is referred to as genome activation. Mutation to remove amino acids from the N terminus of the CP showed that the first 15 RBDV CP residues are not required for genome activation. Other experiments, in which overlapping regions at the CP N terminus were fused to the monomeric red fluorescent protein, showed that sequences downstream of the first 48 aa are not absolutely required for genome activation.

Molecular detection and characterisation of black raspberry necrosis virus and raspberry bushy dwarf virus isolates in wild raspberries

“…the number of reads covering a given base in the reference sequence) was, on average, somewhat lower with RNA1 than RNA2, irrespective of the size of siRNAs mapped. RBDV RNA2 expresses a subgenomic CP‐encoding mRNA that is translated and needed for and enhancement of genome replication (MacFarlane & McGavin, ). RNA2 and the subgenomic RNA tend to accumulate at higher molarities than RNA1 (MacFarlane & McGavin, ), which may proportionally increase the relative abundance of RNA2‐derived siRNAs as compared with RNA1 siRNAs.…”

Genetic characterization of Blueberry necrotic ring blotch virus, a novel RNA virus with unique genetic features

“…However, the RNA motifs may still play a role in genome activation through the binding of other viral proteins, e.g. CP, to the stem–loop structures, as has been the case for ilar-,alfamo- and idaeoviruses among others (Olsthoorn et al , 1999; MacFarlane & McGavin, 2009).…”

Molecular Characterization of the Movement and Coat Proteins of a New Elm Mottle Virus Isolate Infecting European White Elm (Ulmus laevis Pall.)

“…To initiate infection of ilarviruses the binding of CP to the 3'-NTR of the genomic RNAs is required (phenomenon of genome activation). Thus, for the initiation as well as for the propagation of the viral infection, the CP acts as structural key component (Sánchez-Navarro et al, 1997;Pallás et al, 1999;Bol, 2005;MacFarlane and McGavin, 2009). Within the N-terminus of the EMoV CP, an arginine-rich basic motif that is considered to bind to the 3'-NTR of its RNA 3 is determined between amino acid residues 22 and 44 (Pallás et al, 1999;Aparicio et al, 2003;Pallás et al, 2013).…”