Molecular characterization of coat protein genes of serologically distinct isolates of potato virus Y necrotic strain.
The cost protein (CP) genes of two potato virus Y necrotic isolates (N27 and a mutant strain N27-92), which differed in their reactivity to a monoclonal antibody (mab), were characterized. Both isolates could be detected by mab 4E7, but mab VN295.5 selectively reacted to N27 and not to N27-92. The CP genes of both isolates coded for 267 amino acids with approximately 99.0% identity at both the nucleotide and the amino acid levels. nucleotide sequence comparison indicated five substitutions in N27-92 compared with N27. Three of these changes resulted in substitution of amino acids. Two transitions (A-->G) in N27-92 changed threonine to alanine and lysine to arginine at positions 7 and 55, respectively, whereas a A-->T transversion changed asparagine to isoleucine at positions 27. The surface probability curves of both the isolates could almost be superimposed, except at amino acid positions 7 and 27. Since amino acid substitution at position 55 is conservative, changes from polar to hydrophobic amino acids (threonine-->alanine and asparagine-->isoleucine) at positions 7 and 27 might have changed the epitope(s) of N27-92, abolishing its detection by mab VN295.5.
Dhar
A K
AK
Agriculture and Agri-Food Canada, Fredericton Research Center, Canada. adhar_wda@opal.tufts.edu
Singh
R P
RP
D000595:Amino Acid Sequence; D001483:Base Sequence; D002213:Capsid / Q000235:genetics*; D005814:Genes, Viral; D008969:Molecular Sequence Data; D009154:Mutation; D017800:Potyvirus / Q000737:chemistry / Q000145:classification / Q000235:genetics* / Q000276:immunology; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D012703:Serotyping; D011198:Solanum tuberosum / Q000821:virology*