RNA silencing suppressor p19

RNA silencing suppressor p19
The protein dimer formed by two p19 molecules. Each monomer is colored from N-terminus (blue) to C-terminus (red) to illustrate the end-to-end orientation of the dimer. The dotted gray line in the center highlights the dimer interface. From PDB: 1R9F​.[1]
Identifiers
Symbol	Tombus_p19
Pfam	PF03220
InterPro	IPR004905
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary

RNA silencing suppressor p19 (also known as Tombusvirus P19 core protein and 19 kDa symptom severity modulator) is a protein expressed from the ORF4 gene in the genome of tombusviruses. These viruses are positive-sense single-stranded RNA viruses that infect plant cells, in which RNA silencing forms a widespread and robust antiviral defense system. The p19 protein serves as a counter-defense strategy, specifically binding the 19- to 21-nucleotide double-stranded RNAs that function as small interfering RNA (siRNA) in the RNA silencing system. By sequestering siRNA, p19 suppresses RNA silencing and promotes viral proliferation.^[1][2][3] The p19 protein is considered a significant virulence factor^[4] and a component of an evolutionary arms race between plants and their pathogens.^[5]