OXPHOS deficiency activates global adaptation pathways to maintain mitochondrial membrane potential (2021)
Figure 4

Figure 4. mRNA-binding protein Puf3 upregulates Mia40 and global mitochondrial biogenesis to maintain ∆ψm.

The changes of Puf3-associated transcripts encoding mitochondrial proteins in OXPHOS mutants. The RNAseq results in Figure 1C (Dataset EV1) are re-analyzed. Transcripts encoding high fidelity mitochondrial proteins (gene list in Table EV1A) and the Puf3-associated transcripts encoding mitochondrial proteins (gene list 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.

B and C, Deletion of PUF3 upregulates mitochondrial transcripts in WT cells (B), whereas downregulates mitochondrial transcripts in ρ0 cells (C). WT and mutant yeast cells were cultured to log phase. RNAseq was performed with three biological replicates per genotype (Dataset EV4). All the transcripts and the Puf3-associated transcripts encoding mitochondrial proteins 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.

D. Deletion of PUF3 in ρ0 cells downregulates mitochondrial proteins. SILAC analysis of mitochondrial fractions from ρ0 and ρ0 puf3∆ cells are shown. Equal amount of ρ0 cells labeled with heavy amino acids and unlabeled ρ0 puf3∆ cells were mixed to extract mitochondrial fraction for mass-spectrometry analysis. Three biological replicates were prepared for each pair of strains (Dataset EV5). Mitochondrial proteins encoded by Puf3-associated mRNAs are highlighted in red. Mia40 substrates are highlighted in green (gene list in Table EV1E). Mia40 substrates encoded by Puf3 associated transcripts are highlighted in green with red circle. The significantly changed proteins (P value < 0.05; fold change > 1.5 or < 0.67) are highlighted with dashed lines; numbers of significantly changed proteins are indicated.

E. Correlation plots of fold changes (ρ0 puf3∆ versus ρ0) between mitochondrial proteins and their transcripts. Puf3-associated transcripts encoding mitochondrial proteins are highlighted in red. Mia40 substrates are highlighted in green. Mia40 substrates encoded by Puf3 associated transcripts are highlighted in green with red circle.

F. Deletion of PUF3 decreases ∆ψm in ρ0 cells.

G. Deletion of PUF3 decreases the proliferation of ρ0 cells. Serial dilutions (tenfold dilution) of the indicated strains were analyzed on SCD plates at 30℃ for 2 days.

H. Schematic illustration of the consensus Puf3-binding motif Lapointe et al., 2015() and the motif at Mia40 3'-UTR. Mutating the Puf3-binding motif of MIA40 mRNA abolishes Mia40 upregulation in ρ0 cells. Mia40 was endogenously tagged with FLAG and its 3'-UTR was edited as indicated. 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. RC: reverse complement. DE: deletion.

I. Mutating the Puf3-binding motif of MIA40 mRNA decreases ∆ψm of ρ0 cells.

J. Mutating the Puf3-binding motif of MIA40 mRNA impairs the proliferation of ρ0 cells. Cells were cultured from 0.05 OD in SCD, and OD600 was measured every 2 hours.

K. Overexpression of MIA40 rescues ∆ψm of ρ0 puf3∆ cells. Single copy plasmid expressing Mia40 driven by the MIA40 promoter was transformed into the indicated strains.

L. Overexpression of MIA40 rescues the proliferation of ρ0 puf3∆ cells. Strains were prepared as in (K). Cells were cultured from 0.05 OD in SCD, and OD600 was measured every 2 hours.

Cells were cultured to mid-log phase, and stained with 125 nM TMRM for FACS analysis (F, I, K). The red ] highlight two cell lines for comparison (F, G, I, K). Data are mean ± SD from three biological replicates (J, L).