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Repression of mitochondrial translation, respiration and a metabolic cycle-regulated gene, SLF1, by the yeast Pumilio-family protein Puf3p.

Chatenay-Lapointe M, Shadel GS - PLoS ONE (2011)

Bottom Line: Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility.Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling.Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America.

ABSTRACT
Synthesis and assembly of the mitochondrial oxidative phosphorylation (OXPHOS) system requires genes located both in the nuclear and mitochondrial genomes, but how gene expression is coordinated between these two compartments is not fully understood. One level of control is through regulated expression mitochondrial ribosomal proteins and other factors required for mitochondrial translation and OXPHOS assembly, which are all products of nuclear genes that are subsequently imported into mitochondria. Interestingly, this cadre of genes in budding yeast has in common a 3'-UTR element that is bound by the Pumilio family protein, Puf3p, and is coordinately regulated under many conditions, including during the yeast metabolic cycle. Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility. Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling. We also identified the cytoplasmic translation factor Slf1p as yeast metabolic cycle-regulated gene that is repressed by Puf3p at the post-transcriptional level and promotes respiration and extension of yeast chronological life span when over-expressed. Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

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Related in: MedlinePlus

Analysis in strains that over-express Puf3p.Shown is a wild-type strain with a plasmid that over-expresses Puf3p (PUF3) or the corresponding empty vector (vector). (A) Mitochondrial oxygen consumption during early and late log phase. (B) Western blot analysis of protein extracts derived from late log cultures (representative of three biological replicates). (C) Steady-state levels of COX17, COX12, and RIP1 transcripts in late log phase. The values indicate the mean +/− SD with p-values indicated as described in the legend of Figure 1.
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pone-0020441-g003: Analysis in strains that over-express Puf3p.Shown is a wild-type strain with a plasmid that over-expresses Puf3p (PUF3) or the corresponding empty vector (vector). (A) Mitochondrial oxygen consumption during early and late log phase. (B) Western blot analysis of protein extracts derived from late log cultures (representative of three biological replicates). (C) Steady-state levels of COX17, COX12, and RIP1 transcripts in late log phase. The values indicate the mean +/− SD with p-values indicated as described in the legend of Figure 1.

Mentions: Unlike deletion of PUF3, which increased mitochondrial oxygen consumption and OXPHOS protein accumulation during log-phase growth, over-expression of PUF3 did not significantly repress these parameters until later in log phase (Figure 3A and 3B) when cells have already undergone the diauxic shift and significantly increased mitochondrial biogenesis and respiration. Only a modest decline in the Puf3p-target transcript COX17 was observed under these conditions and the two other mitochondrial transcripts analyzed were either minimally effected or not at all (Figure 3C). These data suggest that the repression of respiration by Puf3p over-expression may involve functions other than mRNA transcript decay.


Repression of mitochondrial translation, respiration and a metabolic cycle-regulated gene, SLF1, by the yeast Pumilio-family protein Puf3p.

Chatenay-Lapointe M, Shadel GS - PLoS ONE (2011)

Analysis in strains that over-express Puf3p.Shown is a wild-type strain with a plasmid that over-expresses Puf3p (PUF3) or the corresponding empty vector (vector). (A) Mitochondrial oxygen consumption during early and late log phase. (B) Western blot analysis of protein extracts derived from late log cultures (representative of three biological replicates). (C) Steady-state levels of COX17, COX12, and RIP1 transcripts in late log phase. The values indicate the mean +/− SD with p-values indicated as described in the legend of Figure 1.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3105058&req=5

pone-0020441-g003: Analysis in strains that over-express Puf3p.Shown is a wild-type strain with a plasmid that over-expresses Puf3p (PUF3) or the corresponding empty vector (vector). (A) Mitochondrial oxygen consumption during early and late log phase. (B) Western blot analysis of protein extracts derived from late log cultures (representative of three biological replicates). (C) Steady-state levels of COX17, COX12, and RIP1 transcripts in late log phase. The values indicate the mean +/− SD with p-values indicated as described in the legend of Figure 1.
Mentions: Unlike deletion of PUF3, which increased mitochondrial oxygen consumption and OXPHOS protein accumulation during log-phase growth, over-expression of PUF3 did not significantly repress these parameters until later in log phase (Figure 3A and 3B) when cells have already undergone the diauxic shift and significantly increased mitochondrial biogenesis and respiration. Only a modest decline in the Puf3p-target transcript COX17 was observed under these conditions and the two other mitochondrial transcripts analyzed were either minimally effected or not at all (Figure 3C). These data suggest that the repression of respiration by Puf3p over-expression may involve functions other than mRNA transcript decay.

Bottom Line: Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility.Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling.Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, Yale University School of Medicine, New Haven, Connecticut, United States of America.

ABSTRACT
Synthesis and assembly of the mitochondrial oxidative phosphorylation (OXPHOS) system requires genes located both in the nuclear and mitochondrial genomes, but how gene expression is coordinated between these two compartments is not fully understood. One level of control is through regulated expression mitochondrial ribosomal proteins and other factors required for mitochondrial translation and OXPHOS assembly, which are all products of nuclear genes that are subsequently imported into mitochondria. Interestingly, this cadre of genes in budding yeast has in common a 3'-UTR element that is bound by the Pumilio family protein, Puf3p, and is coordinately regulated under many conditions, including during the yeast metabolic cycle. Multiple functions have been assigned to Puf3p, including promoting mRNA degradation, localizing nucleus-encoded mitochondrial transcripts to the outer mitochondrial membrane, and facilitating mitochondria-cytoskeletal interactions and motility. Here we show that Puf3p has a general repressive effect on mitochondrial OXPHOS abundance, translation, and respiration that does not involve changes in overall mitochondrial biogenesis and largely independent of TORC1-mitochondrial signaling. We also identified the cytoplasmic translation factor Slf1p as yeast metabolic cycle-regulated gene that is repressed by Puf3p at the post-transcriptional level and promotes respiration and extension of yeast chronological life span when over-expressed. Altogether, these results should facilitate future studies on which of the many functions of Puf3p is most relevant for regulating mitochondrial gene expression and the role of nuclear-mitochondrial communication in aging and longevity.

Show MeSH
Related in: MedlinePlus