Amino acid substitutions in the coat protein result in loss of insect transmissibility of a plant virus.
Amino acids near the N terminus of the coat protein of tobacco vein mottling virus were deleted or altered by site-directed mutagenesis to determine the effect on aphid transmissibility of the virus. Deletion of a three amino acid sequence Asp-Ala-Gly, which is conserved in aphid-transmissible potyvirus isolates, abolished transmission. The mutation Ala----Thr in this triplet drastically reduced transmission, whereas the mutation Asp----Asn had no effect, and the mutation Asp----Lys consistently reverted to the wild-type residue. The mutation Lys----Glu, in the residue adjacent to the glycine of the triplet, drastically reduced transmission, whereas the mutation Gln----Pro, seven residues downstream from the glycine had no effect. Comparison of the sequences of other potyviruses suggests that the presence of a glycine residue at the third position of the Asp-Ala-Gly triplet is critical for aphid transmissibility and that certain changes in the residues adjacent to this position abolish or greatly reduce aphid transmissibility.
Atreya
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Department of Plant Pathology, University of Kentucky, Lexington 40546-0091.
Atreya
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Pirone
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D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000235:genetics; D002213:Capsid / Q000235:genetics*; D002872:Chromosome Deletion; D005822:Genetic Vectors; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D015345:Oligonucleotide Probes; D010942:Plant Viruses / Q000235:genetics* / Q000502:physiology; D010947:Plants, Toxic; D010957:Plasmids; D012689:Sequence Homology, Nucleic Acid; D014026:Nicotiana / Q000382:microbiology*; D014158:Transcription, Genetic
D015345:Oligonucleotide Probes