Repression of Mitochondrial Translation, Respiration and a Metabolic Cycle-Regulated Gene, SLF1, by the Yeast Pumilio-Family Protein Puf3p

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.

Translational Capacity of a Cell Is Determined during Transcription Elongation via the Ccr4-Not Complex

“…S1d). Confirming previous evidence of a functional interaction between RBPs and the Ccr4-Not complex, we found that the presence of an RBP motif in the 3’ UTR of a gene, such as Puf3 (Chatenay-Lapointe and Shadel, 2011), Khd1 (Ito et al, 2011), Vts1 (Rendl et al, 2008) and Pab1 (Hogan et al, 2008) was associated with increased Not1 binding. We also observed increased Not1 binding to mRNA isoforms that carried motifs recognized by RBPs such as Pub1 or Nrd1, suggesting functional connections also between these RBPs and the Ccr4-Not complex (Fig.…”

Mitochondrial Respiratory Thresholds Regulate Yeast Chronological Life Span and its Extension by Caloric Restriction

“…Both CR and tor1 Δ alter different aspects of mitochondrial function during exponential growth, and hence they differ in their requirements for respiratory thresholds. Importantly and in agreement with results in puf3 Δ strains, which have increased OXPHOS abundance and respiration but wild-type CLS (Chatenay-Lapointe and Shadel, 2011), our results show that increased respiration during growth (i.e. by HAP4 OE) is not sufficient to extend CLS if it is not accompanied by an enhancement of cell protection systems that promote survival in the stationary phase as for tor1 Δ and CR-treated cells.…”

Genetic manipulation of longevity-related genes as a tool to regulate yeast life span and metabolite production during winemaking

“…In accordance with what happened in laboratory strains, the PUB1 deletion extended CLS. However, the PUF3 deletion, that in some experiments extends CLS [41] and in other does not affect it [44], unexpectedly shortened it (Figure 4A). That suggest an influence of genetic background on Puf3 function.…”