Structural implications into dsRNA binding and RNA silencing suppression by NS3 protein of Rice Hoja Blanca Tenuivirus

Abstract

Rice Hoja Blanca Tenuivirus (RHBV), a negative strand RNA virus, has been identified to infect rice and is widely transmitted by the insect vector. NS3 protein encoded by RHBV RNA3 was reported to be a potent RNAi suppressor to counterdefense RNA silencing in plants, insect cells, and mammalian cells. Here, we report the crystal structure of the N-terminal domain of RHBV NS3 (residues 21-114) at 2.0 Å . RHBV NS3 N-terminal domain forms a dimer by two pairs of a-helices in an anti-parallel mode, with one surface harboring a shallow groove at the dimension of 20 Å 3 30 Å for putative dsRNA binding. In vitro RNA binding assay and RNA silencing suppression assay have demonstrated that the structural conserved residues located along this shallow groove, such as Arg50, His51, Lys77, and His85, participate in dsRNA binding and RNA silencing suppression. Our results provide the initial structural implications in understanding the RNAi suppression mechanism by RHBV NS3.

Functional Diversity of Cytotoxic tRNase/Immunity Protein Complexes from Burkholderia pseudomallei

“…The only hit with a Z-score of Ͼ5 was the N-terminal domain of protein NS3 from rice hoja blanca tenuivirus (Table 3). NS3 suppresses RNA interference pathways in host cells by binding to both siRNA and miRNAs (29,30). Although these proteins superimpose with r.m.s.d.…”

Functional comparison of RNA silencing suppressor between the p5 protein of rice grassy stunt virus and the p3 protein of rice stripe virus

“…RHBVp3, as well as p19 of tomato bushy stunt virus (TBSV) (Ye et al, 2003), also binds the siRNA duplexes in a size-dependent mode. A crystal structural analysis of RHBVp3 revealed that the N-terminal domain of RHBVp3 forms a dimer by two pairs of ␣-helices and that the structure plays an important role in binding to the siRNA duplexes (Hemmes et al, 2007Yang et al, 2013).…”

“…VSRs, including the p3 protein of RSV and RHBV, can bind to the siRNA duplex (Mérai et al, 2006;Lakatos et al, 2006;Hemmes et al, 2007;Xiong et al, 2009;Yang et al, 2013). To determine whether RGSVp5 can bind to siRNA, we performed several gel mobility shift assays.…”

Structural insights into the arms race between host and virus along RNA silencing pathways in Arabidopsis thaliana

“…NS3 was shown to form a dimer in solution and specifically bind to 21 nt dsRNA with high binding affinity (Hemmes et al, 2007(Hemmes et al, , 2009. 10C) (Schnettler et al, 2008;Yang et al, 2011). However, the crystal structure of the N-terminal domain (NTD) of RHBV NS3 (residues 21-114 amino acids) was determined.…”