Rice ragged stunt oryzavirus genome segments S7 and S10 encode non-structural proteins of Mr 68 025 (Pns7) and Mr 32 364 (Pns10)

Abstract

The nucleotide sequences of genome segments S7 and S10 of a Thai-isolate of rice ragged stunt virus (RRSV) were determined. The 1938 bp S7 sequence contains a single large open reading frame (ORF) spanning nucleotides 20 to 1843 that is predicted to encode a protein of M(r) 68,025. The 1,162 bp S10 sequence has a major ORF spanning nucleotides 142 to 1,032 that is predicted to encode a protein of M(r) 32,364. This S10 ORF is preceded by a small ORF (nt 20-55) which is probably a minicistron. Coupled in vitro transcription-translation from the two major ORFs gave protein products of the expected sizes. However, no protein was visualised from S10 when the small ORF sequence was included. Proteins were expressed in Escherichia coli from the full length ORF of S7 (P7) and from a segment of the S10 ORF (P10) fused to the ORF of glutathione S-transferase (GST). Neither fusion protein was recognised by polyclonal antibodies raised against RRSV particles. Furthermore, polyclonal antibodies raised against GST-P7 fusion protein did not recognise any virion structural polypeptides. These data strongly suggest that the proteins P7 and P10 do not form part of RRSV particle. This is further supported by observed sequence homology (though very weak) of predicted RRSV P7 and P10 with those of rice dwarf virus (RDV) non-structural proteins Pns6 and Pns9, respectively.

p2 of Rice grassy stunt virus (RGSV) and p6 and p9 of Rice ragged stunt virus (RRSV) isolates from Vietnam exert suppressor activity on the RNA silencing pathway

“…The RRSV virion is an icosahedral particle that consists of a polyhedral core surrounded by flat spikes approximately 20 nm wide and 10 nm high [27]. The RNA 7 (s7gp1) and 10 (s10gp1) segments encode non-structural proteins p7 and p10 with molecular weights (MW) of 68 and 33 kDa, respectively [28], the RNA 5 segment (s5gp) encodes the 91-kDa structural protein p5 [29], and the RNA 8 segment (s8gp1) encodes the 67-kDa structural protein p8, which is endowed with self-aggregation and self-cleavage abilities [30,31]. The p9 protein encoded by s9gp1 is a 39-kDa protein that contributes largely as a viral spike protein and plays an important role in virus transmission by the insect vector [32,33].…”

Conserved Sequence Motifs for Nucleoside Triphosphate Binding Unique to Turreted Reoviridae Members and Coltiviruses

“…Based on homologies to 2 over the lengths of both proteins, aquareovirus VP5 has been proposed to be a minor core component as well (2). Oryzavirus Pns7 is reported to be a nonstructural protein (30), but given the limited work on this genus, we consider this assignment to be tentative. Instead, we postulate that the proteins with 2-like NTP-binding motifs reside inside the cores of all turreted Reoviridae members and mediate NTPase-related functions similar to those of 2.…”

Recent advances in molecular biology research of a rice pest, the brown planthopper

“…Among the RRSV structural proteins, P5 is a putative capping enzyme with guanylyltransferase activity (Li et al 1996). The capsid protein P3 and RNA-dependent RNA polymerase P4A constitute the polyhedral core particles; the major outer capsid protein P8, along with spike protein P9, form doublelayer virions (Hagiwara et al 1986;Upadhyaya et al 1996Upadhyaya et al , 1997Upadhyaya et al , 1998Zhou et al 2010;Jia et al 2012). Nonstructural proteins are not present in the viral particles.…”