Highlights and prospects of potyvirus molecular biology

The N-terminal P1 proteinase of potato virus Y (ordinary strain group isolate PVY-O) was expressed in E. coli. Antiserum was raised against the expressed protein and used to detect the viral proteins in infected tobacco leaf tissue by Western blotting and by electron microscopy with immunogold labelling. In the immunogold localization studies P1 protein was detected in association with the cytoplasmic inclusion bodies characteristic of PVY infections and in the cytoplasm of the infected plant cells. No significant P1 antibody binding with other plant cell organelles, or with the cell wall and plasmodesmata, was detected by immunogold labelling.

Section: Potato Virus Y (Pvy) Is the Type Member Of The Familymentioning

confidence: 99%

Localization of the P1 protein of potato Y potyvirus in association with cytoplasmic inclusion bodies and in the cytoplasm of infected cells.

Lehto

Pehu

et al. 1998

“…We suggest that the fusion protein is stabilized because of its interaction with product(s) of TEV infection. An attractive hypothesis is that transgenic proteins containing TEV NIa are included in the nuclear inclusions formed by the NIa and NIb replicase following virus infection (Riechmann et al, 1992). Lindbo et al (1993) reported a marked decrease in the steady-state levels of transgene mRNA upon virus inoculation as a consequence of an RNA-mediated co-suppression-like mechanism.…”

Section: Increased Accumulation Of Transgenic Proteins Upon Infectionmentioning

confidence: 99%

“…In an effort to accumulate multiple proteins in transgenic plants we developed an expression cassette based on the nuclear inclusion (NIa) proteinase from tobacco etch potyvirus (TEV) (Marcos & Beachy, 1994). The NIa protein is one of three proteinases in TEV that are responsible for processing the viral polyprotein (Carrington & Dougherty, 1987 ;Riechmann et al, 1992), by cleaving at conserved heptapeptide sequences located in the viral polyprotein Dougherty et al, 1988). NIa is also capable of proper cleavage of a portion of the TEV polyprotein in transgenic plants (Restrepo-Hartwig & Carrington, 1992).…”

Section: Introductionmentioning

confidence: 99%

Transgenic accumulation of two plant virus coat proteins on a single self-processing polypeptide.

Marcos

Beachy²

1997

An expression cassette based on the highly specific tobacco etch potyvirus (TEV) nuclear inclusion (NIa) proteinase has been developed to produce multiple proteins through the translation of a single selfprocessing polypeptide. Gene constructs encoding TEV NIa, the tobacco mosaic tobamovirus (TMV) coat protein (CP) and the soybean mosaic potyvirus (SMV) CP were used to develop transgenic tobacco plants. Proper processing of the multifunctional polypeptide was demonstrated, leading to accumulation of separate proteins in planta. Moreover, the viral genes expressed in this way were biologically

“…Potyviruses possess a ssRNA genome of positive polarity that encodes a single polyprotein (for review see Riechmann et al, 1992). The polyprotein is processed into functional virus proteins by three virus proteinases (Carrington et al, 1990): the P1 proteinase, the helper component-proteinase (HC-Pro) and the nuclear inclusion-a proteinase.…”

Section: Introductionmentioning

confidence: 99%

Nucleic acid-binding properties of a bacterially expressed potato virus Y helper component-proteinase

Maia

Bernardi

1996

The potyvirus helper component-proteinase (HC-Pro) is a multifunctional protein previously reported to have affinity for polyribonucleotides. To investigate further the ability of HC-Pro to bind nucleic acids, the potato virus Y (PVY) LYE84 isolate HC-Pro gene was amplified, cloned in an Escherichia coli expression vector and sequenced. HC-Pro was expressed as a fusion with the maltose-binding protein and purified by affinity chromatography. Electrophoretic mobility-shift assays demonstrated that HC-Pro acts as a sequence nonspecific RNA-binding protein and suggest that more than one molecule of protein was bound per molecule of RNA. The HC-Pro RNA-binding activity was stable in 400 mu-NaC1 and temperature sensitive. The recombinant protein preferentially bound ssRNA over DNA or dsRNA and showed little, if any, affinity for poly(A). The possible implications of the RNA-binding activity of HC-Pro in potyvirus replication and movement are discussed.