Figure 5.

The cox14 defect is not rescued by a ρ⁻ genome with COX1 fused to the 5′-UTR of COB. (A) Map of the mitochondrial bypass suppressor ρ^SUP2. The rearrangement in the suppressor leads to a fusion of the 5′-UTR of COB to nucleotide −174 of COX1 (Manthey and McEwen, 1995). (B) ρ^SUP2 was transferred by cytoduction to a kar1 mutant (Conde and Fink, 1976) lacking mitochondrial DNA (ρ°). The SUP2 suppressor was transferred from the kar1 donor to ρ° derivatives of null mutants of PET309, MSS51, COX14, and SHY1. The different mutants with the SUP2 genome (ρ^SUP2) were then crossed to the isogenic mutants with wild-type mitochondrial DNA (ρ⁺) to obtain the heteroplasmic diploid mutants of PET309 (a/α-ΔPET309/ρ⁺ρ^SUP2), MSS51 (a/α-ΔMSS51/ρ⁺ρ^SUP2), COX14 (a/α-ΔCOX14309/ρ⁺ρ^SUP2), and SHY1 (a/α-ΔSHY1/ρ⁺ρ^SUP2). Serial dilutions of the haploid mutants with wild-type mitochondrial DNA and of the diploid strains with the wild-type and suppressor genomes were spotted on YPD and YPEG plates and incubated at 30°C for 2.5 days.