Tomato bushy stunt virus p19 protein (p19)

The Tomato bushy stunt virus p19 protein (p19) is a potent viral suppressor of RNA silencing (VSR) that plays a critical role in the infection cycle of tombusviruses by neutralizing the host's antiviral RNA interference (RNAi) response (Scholthof, 2006). It functions as a homodimer that specifically recognizes and binds to 19-base pair (bp) double-stranded RNA (dsRNA) with extremely high affinity, acting as a molecular caliper to measure the length of the RNA duplex (Vargason et al., 2003). This 19-bp length is characteristic of the duplex region of small interfering RNAs (siRNAs) produced by Dicer-like enzymes during the initiation of RNAi (Ye et al., 2003). By sequestering these siRNAs, p19 prevents their loading into the RNA-induced silencing complex (RISC), effectively blocking the sequence-specific degradation of viral RNA and facilitating systemic viral spread (Silhavy et al., 2002). In biotechnology and molecular biology, p19 is widely utilized as a tool to enhance the expression of recombinant proteins by suppressing post-transcriptional gene silencing (PTGS) in plant and animal cell systems. Its unique ability to discriminate RNA based on length rather than sequence makes it a valuable model for studying protein-RNA interactions and a potential target for the development of novel antiviral strategies. While primarily an agricultural concern, the structural principles of p19-RNA binding have informed the design of synthetic RNA-binding proteins and diagnostic tools for detecting small RNAs.

Other names

TBSV p19p19 silencing suppressor19 kDa suppressor of RNA silencingp19 VSR

The p19 protein functions as a homodimer that acts as a molecular caliper to specifically recognize and sequester 19-base pair (bp) double-stranded small interfering RNAs (siRNAs). By binding these siRNAs with high affinity, it prevents their incorporation into the RNA-induced silencing complex (RISC), thereby blocking the host's RNA interference (RNAi) defense mechanism and allowing viral RNA to persist and replicate.