Nicotiana Velutina Mosaic Virus: Evidence for a Bipartite Genome Comprising 3 kb and 8 kb RNAs

Abstract

DNA complementary to Nicotiana velutina mosaic virus (NVMV) RNA was 0oned and five segments larger than 0.9 kb were ~used in Northern blot hybridization analysis to identify two virus-specific RNAs, approximately 8 kb (RNA l) and 3 kb (RNA 2) in size. The clones selected as probes did not hybridize with RNA from various tobamoviruses, or from beet necrotic yellow vein (BNYVV) and peanut clump furoviruses. In an attempt to determine the taxonomic position of the virus, about 75 % of the NVMV RNA 2 was sequenced and four open reading frames (ORFs) were identified. ORFs 1, 2 and 3 encode proteins of Mr 20K, 39K and 13K, whereas ORF 4 was incomplete. ORFs 2, 3 and 4 overlapped in an arrangement closely resembling the triple gene block identified in BNYVV RNA 2, barley stripe mosaic virus (BSMV) RNA 2, potato virus X and potato virus M RNA. The presumed coat protein gene ofNVMV RNA 2 (ORF l) is situated to the 5' side of the triple gene block as for BNYVV and BSMV RNA 2. Amino acid homologies were detected among the 13K and 14K proteins of NVMV RNA 2, BNYVV RNA 2 and BSMV RNA 2. Significant homology was also detected between the 39K protein of NVMV RNA 2 and the 42K protein of BNYVV RNA 2, with a motif specific for ATP-and GTPbinding (NTP-binding motif), and a conserved viral DNA polymerase domain. The presence of a triple gene block in NVMV RNA 2 indicates that NVMV has affinities with members of the hordei-, furo-, potexand carlavirus groups but not with the tobamovirus group. The divided RNA genome of NVMV, and the sizes of the two RNAs suggest that NVMV is most closely allied to the furoviruses, but the unique nature of its different biological properties and lack of any serological relationships with furoviruses lead us to conclude that NVMV has no clear relatedness to any taxonomic group of plant viruses.

Nucleotide sequence of the genomic RNA of bamboo mosaic potexvirus

“…BaMV ORFs 3 and 4 are related to the corresponding regions of other potexviruses, predicted to form transmernbrane helices (Forster et al, 1988;Skryabin et al, 1988b;Bancroft et al, 1991). Similar triple gene blocks were found among carlaviruses (Rupasov et al, 1989), barley stripe mosaic hordeivirus (BSMV) (Jackson et al, 1989), beet necrotic yellow vein furovirus (BNYVV) (Richards & Tamada, 1992) and Nicotiana velutina mosaic virus (Randles & Rohde, 1990). Involvement of the triple gene blockencoded proteins in cell-to-cell movement of the virus has been shown for WC1MV (Beck et al, 1991), BSMV (Petty & Jackson, 1990) and BNYVV (Gilmer et al, 1992).…”

Nucleotide Sequence of Shallot Virus X RNA Reveals a 5'-proximal Cistron Closely Related to Those of Potexviruses and a Unique Arrangement of the 3'-proximal Cistrons

“…The ORF2 26K polypeptide contains amino acid motifs which are conserved in NTP-dependent DNA helicases, including the GXGKS/T motif (Gorbalenya et al, 1988). The same conserved motifs are also found in homologous proteins of barley stripe mosaic hordeivirus (58K protein), beet necrotic yellow vein, furovirus (42K protein), and Nicotiana velutina mosaic virus (29K protein) (Rupasov et al, 1989;Randles & Rohde, 1990). Homologies between the ShVX 26K protein and its counterparts of carla-and potexviruses are shown in Table 1.…”

The coat protein of Indian peanut clump virus: relationships with other furoviruses and with barley stripe mosaic virus

“…The significance of the clustering detected by CLUSTALV was assessed by bootstrapping 1 000 samples. Amino acid sequences for comparisons were of the coat proteins of beet necrotic yellow vein furovirus (BNYVV) Eli, barley stripe mosaic hordeivirus (BSMV) [12], Nicotiana velutina mosaic furovirus (NVMV) [19], peanut clump furovirus (PCV) [14], soil-borne wheat mosaic furovirus (SBWMV) [24] and tobacco mosaic virus (TMV) [28]. Figure 1 shows the nucleotide sequence of the 5'-terminal 1128 residues of RNA-2.…”