Disease relevance of orf2

• In summary, this paper reports the first purified recombinant tombusvirus replicase showing high activity and template dependence, a finding that will greatly facilitate future studies on RNA replication in vitro [1].
• Since all genera in Tombusviridae encode comparable replicase proteins, these results may be relevant to other members of this large virus family [2].
• In this work, we obtained a highly active template-dependent replicase complex for Cucumber necrosis tombusvirus (CNV), which is a plus-stranded RNA virus, from Saccharomyces cerevisiae [1].
• Further support for the selectivity of p33 binding in vitro was provided by the inability of the replicase proteins of the closely related Turnip crinkle virus and distantly related Hepatitis C virus to specifically recognize the TBSV IRE [2].
• For this purpose, various replicase-deficient TBSV cDNA constructs were generated and their transcripts were tested for trans-accumulation competence in the presence of helper virus [3].

High impact information on orf2

• Using infection, in vivo expression of green fluorescent protein fusions in plant and yeast cells, and in vitro mitochondrial integration assays, we demonstrate here that both the 36-kDa protein and the complete replicase are targeted to mitochondria and anchor to the outer membrane with the N terminus and C terminus on the cytosolic side [4].
• Inoculation of Nicotiana benthamiana protoplasts with mutant transcripts revealed that null mutations in ORFs 1 [tA33(-)], 2 [tA92(-)] and 6 [tA7(-)], as well as an ORF 2 mutation [tA92GED] in the GDD motif of the 92 kDa protein, the putative replicase, prevented accumulation of detectable levels of progeny RNA [5].
• The genome (4760 nt) has an organization identical to that reported for other tombusviruses except that the pre-readthrough domain of the viral replicase encoded by the 5'-proximal open reading frame (ORF) is larger [6].

References