FIG. 1.
(A) DNA-dependent initiation of B3URA3 replication and subgenomic mRNA transcription. The bracketed region represents a cDNA copy of B3URA3. Single lines represent noncoding regions, and the labeled boxes represent the 3a gene, the URA3 gene, the template RE, the subgenomic RNA4 promoter (SG), and the 3′ TLS. Flanking regions represent a 5′-linked GAL1 promoter and 3′-linked hepatitis delta ribozyme. (B) Nonreplicable, overlapping B3URA3 derivatives used as recombination partners. B3Δ3′ and B3Δ5′ RNAs were transcribed in vivo from plasmids carrying the inducible CUP1 or GAL1 promoter, respectively. B3Δ3′ lacks the coat protein gene and the 3′ TLS. The 3′ end is formed by the ADH1 polyadenylation signal (An). B3Δ5′ has the wt RNA3 5′ UTR and the first half of the 3a coding sequence replaced by the GAL1 leader sequence. B3Δ3′ and B3Δ5′ share ∼0.618 kb of overlapping sequence indicated between vertical dashed lines. Homologous recombination within this common region would generate B3URA3. Sequences used for making parental RNA-specific or common probes for Northern blotting are indicated at the bottom.