Surface-exposed C-terminal amino acids of the small coat protein of Cowpea mosaic virus are required for suppression of silencing.
The small (S) coat protein of Cowpea mosaic virus (CPMV) has been identified previously as a virus-encoded suppressor of post-transcriptional gene silencing (PTGS). Deletions within the C-terminal 24 aa of this protein affect the yield and systemic spread of the virus, suggesting that the C-terminal amino acids of the S protein, which are exposed on the surface of assembled virus particles, may be responsible for the suppressor activity. To investigate this, versions of CPMV RNA-2 with deletions at the C terminus of the S protein were tested for their ability to counteract PTGS in leaf-patch tests. The results showed that the C-terminal 16 aa of the S protein are particularly important for suppressing PTGS and that these amino acids are virus-specific and cannot be substituted by the equivalent sequence from the related virus Bean pod mottle virus.
Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
M Carmen
MC
Cañizares
Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
Kathryn M
KM
Taylor
Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
George P
GP
Lomonossoff
D000595:Amino Acid Sequence; D036022:Capsid Proteins / Q000737:chemistry / Q000235:genetics*; D017798:Comovirus / Q000235:genetics*; D020868:Gene Silencing; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000821:virology; D020079:Terminal Repeat Sequences; D014026:Nicotiana / Q000821:virology*
D036022:Capsid Proteins