SEQUENCING, GENOMIC LOCALIZATION AND INITIAL CHARACTERIZATION OF THE VPG OF PEA ENATION MOSAIC ENAMOVIRUS

The amino acid sequence of the genome-linked viral protein (VPg) of pe a enation mosaic enamo-virus (PEMV) has been determined. The VPg is en coded by nt 1811-1894 within ORF1 of RNA1 downstream of the proteinase motif. Direct N terminus sequencing of intact and endoproteinase Asp- N-digested VPg combined with electrospray mass spectroscopy confirmed that the VPg is composed of 28 amino acids with a molecular mass of 31 38 Da. The context of the N and C terminus residues as well as the pos ition and size of the VPg suggest that the mature VPg may be generated via post-translational proteolytic processing of the polyprotein arra ngement of membrane anchor-proteinase-VPg-polymerase encoded by ORFs 1 and 2. Computer comparisons did not reveal any significant similarity between the VPg of PEMV and any other sequences including those of th e VPgs of related subgroup II luteoviruses.