FIG 4.
Suppression of viral RNA recombination by Rpn11p is independent of the Xrn1p exoribonuclease pathway. (A) Schematic representation of the TBSV RNA recombination pathway based on Xrn1p in yeast. Plasmid-driven expression of the DI-ΔRI (derived from the full-length DI-72 repRNA by deletion of the 5′ RI domain) in the presence of p33 and p92 replication proteins results in partial 5′ truncations by the cellular Xrn1p 5′-to-3′ exoribonuclease, generating DI-RIIΔ70-like degRNAs as shown. DI-Δ70RII-like degRNAs then participate in RNA recombination as indicated. (B) Recombination profile of DI-ΔRI RNA in rpn11-14ts, wt, or xrn1Δ yeasts. The original DI-ΔRI degRNA, DI-RIIΔ70-like degRNAs, and recRNAs are labeled with arrowheads and arrows. Note that the recRNA profile is dramatically different in rpn11-14ts yeast from that seen in xrn1Δ yeast. (C) Half-life of DI-AU-FP repRNA in wt and rpn11-14ts yeasts. Note that yeast did not express p33 and p92 replication proteins.