Structural and phylogenetic analyses of umbravirus and umbra-like virus genomes suggest evolution of capsid-like proteins from 30K movement proteins.
Simon AE, Needham JM, Mikkelsen A, Atallah O
Plant Virus Evolution
Viruses that attack garden vegetables like squash and lettuce have been quietly evolving new tricks to spread on their own—without needing a second 'helper' virus—and mapping that evolutionary leap is the first step toward blocking it.
Some plant viruses are unusual because they have no protein shell of their own and need a second virus to hitch a ride to new plants. Scientists compared the genetic instruction sets of these 'naked' viruses against their distant cousins and found that the cousins appear to have repurposed a protein originally used for traveling inside a plant into a brand-new protective shell. This is a bit like a virus bootstrapping its own vehicle from spare parts, and understanding how it happened could help scientists predict—and prevent—future viral adaptations.
Key Findings
Umbraviruses encode two distinct movement proteins but no capsid protein, making them dependent on helper viruses for insect-mediated transmission to new host plants.
Group 2 umbra-like viruses evolved functional capsid-like proteins that free them from helper-virus dependency, likely enabling independent vector acquisition.
Structural and phylogenetic analyses indicate these capsid-like proteins descended from 30K-type movement proteins, representing a repurposing of cell-to-cell movement machinery into an encapsidation role.
chevron_right Technical Summary
Researchers compared the genetic blueprints of plant umbraviruses and related umbra-like viruses, discovering that the protective protein shells (capsids) found in some of these viruses most likely evolved from proteins that originally served a completely different job: helping the virus move between plant cells.
Abstract Preview
Plant umbraviruses (UVs) encode, in embedded open reading frames, an unstructured movement protein (MP) (ORF3) required for vascular long-distance movement and a structured 30K-type MP (ORF4) for c...
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