The Nucleotide Sequence and Luteovirus-like Nature of RNA 1 of an Aphid Non-transmissible Strain of Pea Enation Mosaic Virus

Abstract

An examination of the genomic strategy of pea enation mosaic virus (PEMV) RNA 1 has verified strong organizational and sequence relationships between PEMV and the beet western yellows-potato leafroll luteovirus subgroup. Sequence analysis of RNA 1 demonstrated five predominant open reading frames (ORFs). The extreme 5' ORF encodes a 34K product of unknown function. The second ORF encodes an 84K product which overlaps 90% of ORF l (in a unique reading frame) and is expressed by internal initiation beginning at the second start codon from the 5' terminus. This protein contains a protease-like motif characteristic of serine-and cysteine-based proteases, suggesting involvement in post-translational processing of viral translation products. The third ORF is characterized by a number of RNA polymerase motifs and a helicase-like motif typical of RNA-dependent RNA polymerases. It overlaps (out of frame) the ORF 2 product and is proposed to be expressed by a frameshift fusion of the ORF 2 and ORF 3 products. The fourth ORF encodes the viral coat protein, and is immediately followed in frame by a 33K ORF thought to represent the aphid transmission subunit of the PEMV virion. Northern blot analysis of polysomeassociated RNA suggests that both products are expressed from an 1800 nucleotide subgenomic mRNA, with the 33K product expressed as a readthrough fusion with the coat protein monomer.

Mutational evidence that the VPg is involved in the replication and not the movement of Pea enation mosaic virus-1

“…and its location within ORF1 of RNA-1. The numbering and arrangement of ORFs are based on Demler & de Zoeten (1991) and Miller et al (1995). The VPg sequences of two naturally occurring isolates of PEMV (∆ and AT + ) differ only in the first amino acid residue (A or T, respectively).…”

Complete Nucleotide Sequence and Organization of the RNA Genome of Groundnut Rosette Umbravirus

“…Indeed, PEMV RNA-2 is capable of infecting plants systemically in the absence of RNA-1 (Demler et al, 1994(Demler et al, , 1996, and such infections resemble those with umbraviruses. Moreover, PEMV RNA-I resembles the genomes of luteoviruses (Demler & de Zoeten, 1991) and the parallel with the luteoviruses that mediate the aphid transmission of umbraviruses is obvious. Thus, as suggested by Demler eta].…”

Transcriptomic analysis of intestinal genes following acquisition of pea enation mosaic virus by the pea aphid Acyrthosiphon pisum

“…PEMV-1 cDNA synthesis was performed using the oligonucleotide 59-TGAAGCTTCGCAGGCAGAGAACTC-39 (HindIII extension) and, after 30 cycles, a 1535 bp DNA encompassing nt 3978-5512 of PEMV-1 (Demler & de Zoeten, 1991) was amplified using primer 59-ACGGATCCCAAGACCCTCCAATAAGC-39 (BamHI extension). For detection of PEMV-2, cDNA synthesis was performed with the oligonucleotide 59-TGAGGAACAGGCTGAATGG-39; in the PCR, this primer together with the oligonucleotide 59-CTAGGACAATGG-CGGTAGG-39 amplified a 547 bp fragment from nt 2755-3301 of PEMV-2 (Demler et al, 1993).…”

“…The PEMV-1 and -2 RNA genomes are encapsidated separately in icosahedral particles with a diameter of 22-30 nm (Demler et al, 1996). PEMV-1 RNA encodes the viral structural proteins -the major coat protein and the minor capsid component, which is essential for aphid transmission and is referred to as the readthrough protein (Demler & de Zoeten, 1991). PEMV-2 is deprived of a coat protein gene and relies on PEMV-1 capsid proteins for its encapsidation and its aphid transmission.…”