OXPHOS deficiency activates global adaptation pathways to maintain mitochondrial membrane potential (2021)
Figure 5

Figure 5. Puf3 hyper-phosphorylation upregulates Mia40 and mitochondrial biogenesis to maintain ∆ψm.

Puf3 is phosphorylated in WT cells and is hyper-phosphorylated in ρ0 cells. Puf3-FLAG was immunoprecipitated from the indicated strains and treated with/without λ-phosphatase, and analyzed by regular and Phos-tag SDS-PAGE.

Puf3 phosphorylation in response to OXPHOS inhibitors and in OXPHOS mutants. WT cells were treated with antimycin (10 μM), KCN (10 μM) or oligomycin (10 μM) for 3 hours, or shifted from SCD to SCEG medium for 3 hours. Whole cell lysates were extracted and equal amount of proteins was loaded for western blot. Treatments and strains with Puf3 hyper-phosphorylation was highlighted in red. Glucose depletion was used as a positive control. Asterisk indicates a non-specific band.

Puf3-15A mutation inhibits Puf3 hyper-phosphorylation in ρ0 cells. A cassette expressing WT or mutant Puf3-FLAG (11A or 15A) under the control of PUF3 promoter was inserted into the HO site in puf3∆ cells. The 15A mutant that blocks Puf3 hyper-phosphorylation is highlighted in red. Puf3-FLAG was immunoprecipitated from the indicated strains and analyzed by regular and Phos-tag SDS-PAGE.

Puf3-15A mutation inhibits Puf3 hyper-phosphorylation upon oligomycin treatment and in ∆V and ρ0 cells. WT cells were treated with antimycin (10 μM), KCN (10 μM) or oligomycin (10 μM) for 3 hours, or shifted from SCD to SCEG medium for 3 hours. Whole cell lysates were extracted and equal amount of proteins was loaded for western blot. Asterisk indicates a non-specific band.

Puf3-15A mutation downregulates Puf3-associated mitochondrial transcripts in ρ0 cells. ρ0 and ρ0 puf3-15A cells were cultured to log phase. RNAseq was performed with three biological replicates per genotype (Dataset EV7). All the transcripts and the Puf3-associated transcripts encoding mitochondrial proteins (gene lists in Table EV1D) are shown. The significantly changed transcripts (P value < 0.05; fold change > 1.5 or < 0.67) are highlighted with dashed lines; numbers of significantly changed transcripts are indicated.

Puf3-15A mutation inhibits the upregulation of Mia40 in ∆V and ρ0 cells. Mia40 was endogenously tagged with FLAG. The selection markers were removed by the Cre-loxP system. Whole cell lysates were extracted and equal amount of proteins was loaded for western blot.

Puf3-15A mutation decreases ∆ψm in ρ0 cells. Cells were cultured to mid-log phase and stained with 125 nM TMRM for FACS analysis. The red ] highlight two cell lines for comparison.

Puf3-15A mutation has no effect on the proliferation of WT cells.

Puf3-15A mutation inhibits the proliferation of ρ0 cells.

Mia40 overexpression rescues the proliferation defect of ρ0 puf3-15A cells. Single copy plasmid expressing Mia40 driven by MIA40 promoter was transformed into the indicated strains.

Cartoon illustration that Puf3-hyperphosphorylation in ∆V and ρ0 cells upregulates Puf3-associated mitochondrial transcripts, especially Mia40, to enhance mitochondrial biogenesis and ∆ψm maintenance.

Cells were cultured from 0.05 OD in SCD, and OD600 was measured every 2 hours; Data are mean ± SD from three biological replicates (H, I, J).