Virus Host Jumping Can Be Boosted by Adaptation to a Bridge Plant Species.

Understanding biological mechanisms that regulate emergence of viral diseases, in particular those events engaging cross-species pathogens spillover, is becoming increasingly important in virology. Species barrier jumping has been extensively studied in animal viruses, and the critical role of a suitable intermediate host in animal viruses-generated human pandemics is highly topical. However, studies on host jumping involving plant viruses have been focused on shifting intra-species, leaving aside the putative role of "bridge hosts" in facilitating interspecies crossing.

Common and Strain-Specific Post-Translational Modifications of the Potyvirus Coat Protein in Different Hosts.

Phosphorylation and -GlcNAcylation are widespread post-translational modifications (PTMs), often sharing protein targets. Numerous studies have reported the phosphorylation of plant viral proteins. In plants, research on -GlcNAcylation lags behind that of other eukaryotes, and information about -GlcNAcylated plant viral proteins is extremely scarce.

Potyviral coat protein and genomic RNA: A striking partnership leading virion assembly and more.

Potyvirus genus clusters a significant and expanding number of widely distributed plant viruses, responsible for large losses impacting most crops of economic interest. The potyviral genome is a single-stranded, linear, positive-sense RNA of around 10kb that is encapsidated in flexuous rod-shaped filaments, mostly made up of a helically arranged coat protein (CP). Beyond its structural role of protecting the viral genome, the potyviral CP is a multitasking protein intervening in practically all steps of the virus life cycle.

Phosphorylation-Related Crosstalk Between Distant Regions of the Core Region of the Coat Protein Contributes to Virion Assembly of Plum Pox Virus.

Eukaryotic proteins are often targets of posttranslational modifications (PTMs). Capsid protein (CP) of plum pox virus (PPV), a member of genus , has been reported to be prone to phosphorylation in four serines at the N-terminal region. CP phosphorylation has been proposed to influence PPV infection by regulating CP accumulation in coordination with a second PTM, GlcNAcylation.

Phosphorylation coexists with O-GlcNAcylation in a plant virus protein and influences viral infection.

Phosphorylation and O-GlcNAcylation are two widespread post-translational modifications (PTMs), often affecting the same eukaryotic target protein. Plum pox virus (PPV) is a member of the genus Potyvirus which infects a wide range of plant species. O-GlcNAcylation of the capsid protein (CP) of PPV has been studied extensively, and some evidence of CP phosphorylation has also been reported.

Resistance to Plum pox virus strain C in Arabidopsis thaliana and Chenopodium foetidum involves genome-linked viral protein and other viral determinants and might depend on compatibility with host translation initiation factors.

Research performed on model herbaceous hosts has been useful to unravel the molecular mechanisms that control viral infections. The most common Plum pox virus (PPV) strains are able to infect Nicotiana species as well as Chenopodium and Arabidopsis species. However, isolates belonging to strain C (PPV-C) that have been adapted to Nicotiana spp.

Analysis of the subcellular targeting of the smaller replicase protein of Pelargonium flower break virus.

Replication of all positive RNA viruses occurs in association with intracellular membranes. In many cases, the mechanism of membrane targeting is unknown and there appears to be no correlation between virus phylogeny and the membrane systems recruited for replication. Pelargonium flower break virus (PFBV, genus Carmovirus, family Tombusviridae) encodes two proteins, p27 and its read-through product p86 (the viral RNA dependent-RNA polymerase), that are essential for replication.

A membrane-associated movement protein of Pelargonium flower break virus shows RNA-binding activity and contains a biologically relevant leucine zipper-like motif.

Two small viral proteins (DGBp1 and DGBp2) have been proposed to act in a concerted manner to aid intra- and intercellular trafficking of carmoviruses though the distribution of functions and mode of action of each protein partner are not yet clear. Here we have confirmed the requirement of the DGBps of Pelargonium flower break virus (PFBV), p7 and p12, for pathogen movement. Studies focused on p12 have shown that it associates to cellular membranes, which is in accordance to its hydrophobic profile and to that reported for several homologs.

Identification and characterization of RNA-binding activity in the ORF1-encoded replicase protein of Pelargonium flower break virus.

Pelargonium flower break virus (PFBV) belongs to the genus Carmovirus (family Tombusviridae) and, as with the remaining members of the group, possesses a monopartite genome of single-stranded, positive-sense RNA that contains five ORFs. The two 5'-proximal ORFs (ORFs 1 and 2) encode two polypeptides of 27 and 86 kDa (p27 and p86), respectively, that show homology with replication proteins. The p27 does not present any motif to explain its presumed involvement in replication, while p86 has the motifs conserved in RNA-dependent RNA polymerases.

Inhibition of RNA silencing by the coat protein of Pelargonium flower break virus: distinctions from closely related suppressors.

Viral-derived double-stranded RNAs (dsRNAs) activate RNA silencing, generating small interfering RNAs (siRNAs) which are incorporated into an RNA-induced silencing complex (RISC) that promotes homology-dependent degradation of cognate RNAs. To counteract this, plant viruses express RNA silencing suppressors. Here, we show that the coat protein (CP) of Pelargonium flower break virus (PFBV), a member of the genus Carmovirus, is able to efficiently inhibit RNA silencing.