Mitochondrial ubiquinone-mediated longevity is marked by reduced cytoplasmic protein translation

Mutations in the clk-1 gene impair mitochondrial ubiquinone biosynthesis and extend the lifespan of C. elegans. We demonstrate here that this life extension is linked to the repression of cytoplasmic protein translation. Clk-1 mutations inhibit polyribosome formation similarly to daf-2 mutations that dampen insulin signaling. Comparisons of total versus polysomal RNAs in clk-1 mutants reveal a reduction in the translational efficiencies of mRNAs coding for elements of the translation machinery and an increase in those coding for the oxidative phosphorylation and autophagy pathways. Knocking down the transcription initiation factor TAF-4, a protein that becomes sequestered in the cytoplasm during early embryogenesis to induce transcriptional silencing, ameliorates the clk-1 inhibition of polyribosome formation. These results underscore a prominent role for the repression of cytoplasmic protein translation in eukaryotic lifespan extension, and suggest that mutations impairing mitochondrial function are able to exploit this repression similarly to reductions of insulin signaling. Moreover, this report reveals an unexpected role for TAF-4 as a repressor of polyribosome formation when ubiquinone biosynthesis is compromised.


Introduction
Slowing down mitochondrial metabolism is a well-known means of increasing the lifespan of multiple species (Breitenbach et al., 2014, Copeland et al., 2009, Dillin et al., 2002, Houtkooper et al., 2013. In C. elegans, one such model is the clk-1(mq30) mutant that harbors a deletion in the gene encoding a ubiquinone (UQ) biosynthesis enzyme (Felkai et al., 1999). Ubiquinone is a redox-active lipid that plays a central role in the electron transport chain and mitochondrial oxidative phosphorylation (OXPHOS) by carrying electrons from complexes I and II to complex III (Stefely & Pagliarini, 2017). In addition to lifespan extension and decreased respiration, clk-1 mutants are developmentally delayed and have reduced progeny (Felkai et al., 1999).
Mammalian Clk1, known as Mclk-1 or Coq7, is also involved in lifespan (Liu et al., 2005, Stepanyan et al., 2006, Takahashi et al., 2014. Transgenic mice, rescued from embryonic lethality via the transgenic expression of mouse clk-1, with reduced Clk1 expression live longer and have smaller bodies than wild-type mice, demonstrating a conserved role for clk-1 in longevity across species (Takahashi et al., 2014). However it is not fully understood how the reduction of ubiquinone biosynthesis extends the lifespan of these animals.
Until recently, CLK-1 protein was thought to reside exclusively in the mitochondria. However, a distinct nuclear form of CLK-1 has been reported to independently regulate lifespan by mitochondrial-nuclear retrograde signaling (Monaghan et al., 2015). Adding back a copy of the clk-1 gene that lacks the mitochondrial targeting signal (MTS) to the clk-1 deletion mutant led to a subtle but significant reduction in the lifespan extension phenotype observed in the full clk-1 deletion mutant (Monaghan et al., 2015). However, the existence and function of a nuclear form of CLK-1 remains controversial. Other studies fail to detect any nuclear localization of the MCLK1/CLK-1 proteins or any biological activity of a C. elegans CLK-1 protein devoid of an MTS (Liu et al., 2017).
The importance of communication between stressed mitochondria and the rest of the cell is becoming increasingly appreciated (Quiros et al., 2016). One such reaction to stress is carried out by the mitochondrial unfolded protein response (UPR mt ) (Baker et al., 2012, Durieux et al., 2011, Houtkooper et al., 2013. GCN-2, an eIF2α kinase that modulates cytosolic protein synthesis, is phosphorylated in response to the activated UPR mt in clk-1 mutants in a manner required for lifespan extension (Baker et al., 2012). Another non-mitochondrial factor, TATAbinding protein associated factor (TAF-4), is a transcription factor that has been implicated in the extension of clk-1 mutant lifespan (Khan et al., 2013). TAF-4 was identified in an RNA interference (RNAi) screen for transcription factors required for the lifespan extension of clk-1 mutants (Khan et al., 2013). Beyond clk-1, TAF-4 was also required for the lifespan extension phenotype of two mutants of the mitochondrial electron transport chain (isp-1 and tpk-1) (Khan et al., 2013). TAF-4 is a component of the TFIID mRNA transcription complex and is best known for its role in transcriptional silencing in early embryogenesis by becoming sequestered in the cytoplasm due to phosphorylation by OMA-1 (Walker et al., 2001). The loss of TAF-4 in C.
elegans suppresses the lifespan extension phenotype induced by clk-1 mutations, however the mechanism through which this happens is not known.
Reducing protein translation is another well-known means by which eukaryotes extend lifespan (Hansen et al., 2007, Pan et al., 2007. Caloric restriction, amino acid reduction, and knocking down myriad factors involved in protein translation (such as ribosomal proteins, elongation/initiation factors, or tRNA synthetases) all increase lifespan (Hansen et al., 2007, Masoro, 2000, Min & Tatar, 2006, Pan et al., 2007. The genetic or pharmacological inhibition of the mTOR/nutrient sensing pathway or insulin receptor signaling pathway is also marked by reduced protein translation rates and a suppression of polyribosome formation (Genolet et al., 2008, Stout et al., 2013. Proteomic analysis of the daf-2 mutants previously revealed a substantial reduction of ribosomal proteins, translation factors, and protein metabolism components coupled to a repression of polyribosome formation (Stout et al., 2013). Moreover, our previous work demonstrated that similarly to daf-2 mutants, mutations in clk-1 worms also result in a strong repression of polyribosome formation (Essers et al., 2015). This led us to hypothesize the existence of unexplored regulatory links between dysfunctional mitochondria and cytoplasmic protein translation that are contributing to eukaryotic lifespan extension. In particular, we investigated which subsets of mRNAs are preferentially translated in the longerlived C. elegans with impaired ubiquinone biosynthesis.

RNAseq of clk-1 strains shows major changes in transcription
To uncover how the transcriptome of C. elegans changes on deletion of clk-1 and the influence of the clk-1 mitochondrial localization signal, we performed next-generation sequencing of total RNAs (depleted of rRNA) isolated from worms at the L4 stage that precedes young adulthood.
The clk-1(qm30) +WT mutants have wild-type phenotypes and are rescued with fully functioning clk-1 and, while the clk-1(qm30) +nuc mutants have clk-1 only residing in the nucleus and not in the mitochondria (Monaghan et al., 2015). The principal component analysis (PCA) plot and correlation matrix show the expected clustering of the biological triplicates of each strain (Fig 1B-C). Major changes were observed in the RNA pool of the clk-1(mq30) +WT mutants compared with either clk-1(mq30) or clk-1(mq30) +nuc , with 9626 and 8685 genes being differentially expressed, respectively. Far fewer differentially expressed genes were measured when comparing clk-1(mq30) to clk-1(mq30) +nuc , with only 247 genes upregulated and 571 genes downregulated.
The subtle changes in RNA expression are consistent with the observation that introducing the nuclear form of clk-1 in clk-1(mq30) results in only small phenotypic changes compared to the clk-1(mq30) mutants (Liu et al., 2017, Monaghan et al., 2015.

Transcripts encoding the translation machinery are strongly reduced in clk-1 strains
We next established the biological pathways involved in clk-1 mediated longevity using DAVID and GO analysis (Huang da et al., 2009a, Huang da et al., 2009b. Among the most upregulated processes in clk-1(mq30) are metabolic pathways (e.g. oxidation-reduction pathway) and ion transport ( Fig 1D). A substantial part (25%) of significantly downregulated processes in clk-1 mutants is involved in reproduction and development ( Fig 1D). Developmental delay and reduced progeny have been extensively reported in clk-1 mutants, and are often described to come at a cost of longevity (Larsen et al., 1995, Tissenbaum & Ruvkun, 1998. Remarkably, another 20% of downregulated GO terms are involved in protein translation and mRNA processing ( Fig 1D). In total, 38 genes encoding ribosomal proteins, initiation and elongation factors are downregulated in the clk-1(mq30) mutants compared to clk-1(mq30) +WT . In addition, 28 genes specifically involved in biogenesis and processing of ribosomes were downregulated in the clk-1(mq30) worms. Similar downregulation of ribosomal proteins and initiation/elongation factors was observed in the clk-1(mq30) +nuc mutants. These observations suggest that protein translation is repressed in the clk-1(mq30)/ +nuc mutants, and are in line with the repressed polysome profiles we observed before (Essers et al., 2015).

There is a minor role for nuclear clk-1 in transcriptional changes
Since the nuclear form of clk-1 was suggested to associate with the chromatin in the nucleus (Monaghan et al., 2015), we expected changes in the transcriptome in the mutant expressing exclusively the nuclear form of clk-1. However, differentially expressed genes in clk-1(mq30) +nuc were very similar to the differentially expressed genes clk-1(mq30) (Fig 2A). There were 3720 genes similarly upregulated in the clk-1(mq30) +nuc as in the total clk-1(mq30) mutant compared to clk-1(mq30) +WT and 4397 genes similarly downregulated in both strains compared to the wildtype control (Fig 2B). The 292 upregulated genes and 275 downregulated genes in the clk-1(mq30) +nuc strain that were not up-or downregulated in the clk-1(mq30) strain did not lead to significantly clustered GO terms. The 704 genes upregulated in specifically the clk-1(mq30) strain and not in the clk-1(mq30) +nuc strain were involved in biological processes such as ion transport and oxidation-reduction ( Fig 2C). The 805 genes downregulated in the clk-1(mq30) strain but not in clk-1(mq30) +nuc were involved in biological processes such as reproduction and response to DNA damage stimuli ( Fig 2C). These processes also appeared when comparing the clk-1 mutants to wild-type worms.

Translation rates are reduced in clk-1(mq30) worms
In order to provide a snapshot of the translational status in the clk-1(mq30) strains, we performed polysome profiling of C. elegans at the L4 stage. Polysome profiling fractionates total cell lysate over a sucrose gradient by density and enables the distinct measurement of 40S small ribosomal subunits, 60S large ribosomal subunits, 80S monosomes (an mRNA molecule with a single ribosome attached) and multiple polysomes (mRNA molecules with multiple ribosomes attached). Polysome profiles of clk-1(mq30) reveal a strong repression of both monosomal and polysomal peaks compared to clk-1(mq30) +WT , suggesting a global repression of protein translation (Fig 3). Again, the clk-1(mq30) +nuc mutants show similar yet slightly less dramatic differences compared to wild-type vs. the total clk-1(mq30) mutant compared to wildtype (Fig 3). Since the clk-1(mq30)+nuc does not show striking differences in transcription compared to the total clk-1(mq30) mutant, we focused our remaining studies on comparing clk-1(mq30) to clk-1(mq30)+WT. The polysome profiles, together with the RNAseq results, show that clk-1 mutants are marked by repressed protein translation. Further validation of translational repression in clk-1 mutants is shown by qPCR analysis of several mRNAs encoding EIFs and ribosomal proteins that shows bona fide downregulation of these genes in clk-1(mq30) worms ( Fig S1).

Total RNA does not mirror highly translated polysomal RNA
In addition to providing a global overview of protein translation rates, polysome profiling allows the specific isolation of the RNAs associated with the polyribosomes for comparison with the total RNAs in different clk-1 strains ( Fig 4A). We observed that changes in the polysomal RNA of clk-1(mq30) compared to the polysomal RNA of clk-1(mq30) +WT were not simply mirroring the changes observed in the total mRNA pools of these mutants ( Fig 4B). For instance, there are 434 genes specifically upregulated in polysomal RNA pool carrying highly translated messages that are not upregulated in the total RNA pool of clk-1(mq30) mutants ( Fig 4C). A larger set of 1657 genes is upregulated in both polysomal and total RNA, while the largest part (2767 genes) is exclusively upregulated in the total RNA pool ( Fig 4C). A similar pattern is observed with downregulated genes in clk-1(mq30) mutants, with 466 genes detected in the polysomal RNA pool, 2574 in both polysomal and total RNA pools, and 2628 in the strictly total RNA pool ( Fig   4C)

OXPHOS transcripts are highly enriched in polysomal RNA of clk-1(mq30) strains
In order to determine the functional relevance of the differentially expressed RNAs in total and polysomal RNA pools, we performed DAVID GO analysis. For instance, ion transport processes are upregulated in the total mRNA of clk-1(mq30) mutants. However, the polysomal expression data indicate that despite this higher abundance in the total pool, mRNAs coding for ion transport are not more highly translated in clk-1(mq30) mutants ( Fig 4D). In contrast, mRNAs involved in metabolic processes such as oxidation-reduction, glycolysis, and lipid metabolism are substantially upregulated in both the total and the polysomal RNA pools ( Fig 4D). This suggests a metabolic compensation for the reduction of OXPHOS capacity by glycolysis and lipid metabolism in the clk-1(mq30) mutants. Processes that were exclusively upregulated in the polysomal RNA pool (and thus exclusively highly translated) in clk-1 mutants are involved in ATP hydrolysis, protein import into mitochondria, and mitochondrial electron transport ( Fig 4D). More specifically, 50 transcripts encoding proteins involved in mitochondrial oxidative phosphorylation were enriched in clk-1 polysomes (Table 1). This up regulation does not seem complex-specific, since mRNAs coding for proteins of all OXPHOS complexes (I-V) were enriched in clk-1 polysomes. These data suggest a model whereby proteins involved in ATP production and the import of these proteins into the mitochondrial are highly translated despite lower overall expression levels in clk-1 mutants compared to WT in order to attempt to overcome their energy deficit.

RNAs coding for ribosomal proteins are substantially reduced in clk-1 polysomes
An even more substantial downregulation of transcripts involved in translation and ribosome biogenesis processes was revealed in the polysomal RNA pool of clk-1 deficient worms compared to clk-1(mq30) +WT , confirming the repression of translational machinery proteins (Table 2). In the polysomal RNA pool of clk-1(mq30) mutants, 62 ribosomal proteins, 16 elongation/initiation factors, 14 amino-acyl tRNA synthetases, and 10 other proteins involved in mRNA processing were downregulated (Table 2). These results are reminiscent of the proteomic analysis demonstrating a significant reduction of ribosomal proteins and translation factors in the daf-2 insulin receptor mutants (Stout et al., 2013). Furthermore, a subset of these transcripts coding for proteins involved in translation (21 ribosomal proteins, 11 Amino-acyl tRNA synthetases, and 8 other elongation/initiation factors) was even downregulated in the total pool of RNA. This indicates that the downregulation of translation machinery is partially regulated in a transcriptional manner. Taken together, it appears that an attempt to overcome an energy deficit in clk-1 mutants is coupled to the suppression of ribosome biogenesis and mRNA translation, which would conserve flagging energy for other critical cell processes.

Differential translational efficiency (TE) of mRNA reveals a role for TOR signaling
Since there are mRNAs that are selectively being translated in the clk-1 mutant or the wild-type independently of their abundance in the total mRNA pool, we calculated the translational efficiency (TE) of individual mRNA transcripts by taking the ratio between total RNA and polysomal RNA ( Fig 5A). DAVID GO analysis on transcripts with high or low TE revealed similar biological processes as observed in the groups of genes specifically up and downregulated in the polysomal RNA presented in fig 4D (Fig 5B). The list of genes with significantly different TEs was then analyzed using the 'worm longevity pathway' in KEGG (Ogata et al., 1999) using pathview (Luo & Brouwer, 2013), to investigate overlap in longevity pathways known in C.
elegans. Besides hits in the UPR mt and stress resistance, both already described in clk-1 mutants (Durieux et al., 2011), the results also revealed possible involvement of the mTOR signaling pathway in the clk-1 mutants. Hence, we also checked the mTOR signaling pathway in KEGG pathview. In C. elegans, homologs of TOR pathway genes all extend lifespan in C. elegans upon siRNA knockdown (Korta et al., 2012). Interestingly, our RNAseq data show that let-363 (homologue of TOR) is preferentially translated in wild-type but not in clk-1 mutants ( Fig   5C). Other members of the TOR complex 1 (TORC1) including daf-15 (RAPTOR), clk-2 (TEL2), R10H10.7 (TTI1), also showed decreased TE in clk-1 mutants ( Fig 5C). Moreover, our results show that a key player in autophagy, lgg-1, is preferentially translated in clk-1(mq30) mutants but not in the clk-1(mq30) WT ( Fig 5C).

taf-4 is required for repressed polysome profiles in clk-1(mq30)
TAF-4 is one of few transcription factors reported to be critical for the clk-1 longevity phenotype (REF). In order to test if TAF-4 has a role in polysome formation in clk-1(mq30) worms, we performed RNAi of taf-4 in the clk-1(mq30) mutants. Here we show that RNAi of taf-4 significantly increases the monosomal and polysomal peaks of clk-1(mq30) compared to the control empty vector HT115 (Fig 6A,C), suggesting this transcription factor plays a direct role in the suppression of polyribosome formation upon the loss of ubiquinone biosynthesis. This increase is not observed in te polysome profiles upon taf-4 RNAi in the clk-1(mq30) +WT ( Fig 6B).
These data suggest that TAF-4 loss restores polyribosome formation in clk-1 mutants similar to the previously reported attenuation of the longevity phenotype (Khan et al., 2013). Taken all together, these results confirm a role of reduced cytosolic protein translation in the lifespan extension of the clk-1 mutants by changing the TE of specific mRNAs coding for the translation machinery and by activating an unappreciated role of TAF-4 in repressing polyribosome formation.

Discussion
This study was initiated following our previous observation that the polysome profiles of clk-1 mutants revealed the same repression of polysomes as in the daf-2 mutants (Essers et al., 2015). We continued this line of inquiry by isolating and sequencing polysomal and total RNAs from clk-1 mutants and compared them with clk-1 +WT worms. These results demonstrated that compared to clk-1 +WT , very few mRNAs coding for components of the translation machinery such as initiation factors, elongation factors, and ribosomal proteins are present on clk-1 polyribosomes. In contrast, the clk-1 polyribosomes reveal a strong preference for translating RNAs coding for OXPHOS proteins. The reduction in the TE of mRNAs coding for the translation machinery is highly reminiscent of the proteomic landscape we described in the daf-2 mutants, where there is a scarcity of RPs yet also no appreciable reduction in total RP mRNA expression (Depuydt et al., 2013, Essers et al., 2015. Taken all together, the results suggest that shutting down protein translation by altering the TE of mRNAs coding for the translation machinery is a common mechanism used by several different systems that drive lifespan extension. Our results go on to suggest that the proposed nuclear form of CLK-1 has a relatively small effect on alleviating the polyribosome reduction observed in the clk-1 mutants. The subtle differences in lifespan and development previously described before (Monaghan et al., 2015) might be explained by reestablishing expression of some reproduction genes in the clk-1(mq30) +nuc mutant, which are well known to associate to lifespan (Hsin & Kenyon, 1999, Monaghan et al., 2015. Since it has been shown that under certain conditions proteins may be imported into the mitochondria without any MTS (Ruan et al., 2017), it is possible that a small proportion of the nuclear CLK-1 enters the mitochondria without a MTS. This current study does not disprove the existence of nuclear form of CLK-1, however an obvious function of a nuclear CLK-1 is not apparent with these data.
In this study, we confirm the importance of retrograde communication between stressed mitochondria and the rest of the cell. In Drosophila, it was shown that dietary restriction-induced Our results found mRNAs coding for OXPHOS complexes I-V substantially enriched on polysomes of clk-1(mq30) worms. Given the marked reduction of total polysomes in these mutants, we can assume that the majority of the few remaining polysomes are present solely to maintain OXPHOS complexes at viable levels. This translational up regulation of OXPHOS mRNAs on ribosomes was also recently observed by ribosome profiling in the context of host shutoff during Vaccinia virus infection in human cells (Dai et al., 2017). This host shutoff facilitates resource availability for viral evasion, and is coupled to a global inhibition of protein synthesis in the host (Bercovich-Kinori et al., 2016). Additionally, the authors propose that this translational up regulation of OXPHOS transcripts is due to their relatively short 5′ untranslated regions (UTRs), which are known to play a regulatory role in TE (Dai et al., 2017) (Araujo et al., 2012). A similar mechanism coupling energy metabolism and translational control is observed in the present study in the context of longevity.
Besides for OXPHOS transcripts, this study also identified an increased TE for the autophagy gene lgg-1, the C. elegans orthologue of LC3 in humans. Autophagy is an indispensable function in organisms undergoing lifespan extension. In the absence of bec-1, the C. elegans orthologue of the autophagy gene APG6/VPS30/beclin1, daf-2 mutant worms fail to undergo lifespan extension (Melendez et al., 2003). Reducing bec-1 in worms subject to caloric restriction (eat-2 mutants) or inhibition of the mTOR pathway (reducing let-363 (TOR) or daf-15 (RAPTOR) expression) also has the same effect of preventing lifespan extension (Hansen et al., 2008). Our results suggest a novel mechanism for inducing autophagy in systems undergoing lifespan extension by increasing the TE of mRNAs coding for crucial components of the pathway.
Finally, we found an unexpected role for TAF-4 as a repressor of polyribosome formation when ubiquinone biosynthesis is compromised. Though TAF-4 is essential for all RNA transcription in the early embryo in C. elegans (Walker et al., 2001), this requirement is different in later developmental stages and worms exposed to taf-4 RNAi starting from L1 throughout their remaining life grow normally (Khan et al., 2013). The authors propose a role for TAF-4 in the retrograde response model of longevity in mutants with dysfunctional mitochondria. In this model dysfunctional mitochondria signal via cAMP response element-binding (CREB) proteins to activate TAF-4 in a way that increases life-extending gene expression. Here we show that one of the consequences of TAF-4 loss in clk-1 mutants, and perhaps also in isp-1 and tpk-1 mutants, is a failure of the system that shuts down protein translation in response to mitochondria impairment. This unexpected ability of TAF-4 to control protein translation will be very interesting for further study.
This study demonstrates that molecular pathways of long-lived clk-1 mutants with dysfunctional mitochondria converge with those of other distinctly different long-lived mutants to reduce cytoplasmic protein translation. It also reveals a striking change in the transcripts that the polyribosomes prefer to translate when mitochondria are compromised. Ribosomal proteins and other proteins part of the translation machinery are very marginally translated while the mitochondrial OXPHOS genes are still robustly translated despite a substantial reduction in the number of polysomes. We propose that this mechanism is likely recapitulated in many more models of lifespan extension, and reaffirms studies that aim to extend human lifespan by reducing protein translation.
Synchronized worms were harvested and snap frozen at L4 larval stage for either total mRNA isolation or polysome profiling. For RNAi knock down experiments, synchronized eggs were plated on NGMi (containing 2 mM IPTG) with a bacterial lawn of either E. coli HT115 (RNAi control strain, containing an empty vector) or taf-4 RNAi bacteria.

Polysome Profiling
Gradients of 17-50% sucrose (11 ml) in gradient buffer (110 mM KAc, 20 mM MgAc2 and 10 mM HEPES pH 7.6) were prepared on the day before use in thin-walled, 13.2 ml, polyallomer 14 89 mm centrifuge tubes (Beckman-Coulter, USA). Nematodes were lysed in 500 ml polysome lysis buffer (gradient buffer containing 100 mM KCl, 10 mM MgCl2, 0.1% NP-40, 2 mM DTT and RNaseOUT™ (Thermofischer scientific)) using a dounce homogenizer. The samples were centrifuged at 3500 g for 10 min to remove debris and the supernatant was subjected to BCA protein assay. In all, 500 mg of total protein for each sample was loaded on top off the sucrose gradients. The gradients were ultra-centrifuged for 2 h at 40.000 rpm in a SW41Ti rotor (Beckman-Coulter, USA). The gradients were displaced into a UA6 absorbance reader (Teledyne ISCO, USA) using a syringe pump (Brandel, USA) containing 60% sucrose.
Absorbance was recorded at an OD of 254 nm. All steps of this assay were performed at 4°C or on ice and all chemicals came from Sigma-Aldrich (St Louis, MO, USA) unless stated otherwise.
Polysome peaks were quantified by measuring area under the curve (AUC) in ImageJ.

Total/Polysomal RNA isolation
For isolation of total RNA, worms were homogenized with a 5 mm steel bead using a TissueLyser II (Qiagen) for 5 min at frequency of 30 times/sec in the presence of TRIzol (Invitrogen) and isolation was continued according to manufacturer's protocol. Polysomal fractions from two experiments were pooled and mRNA was extracted using TRIzol LS (Invitrogen) according to the manufacturer's protocol. Contaminating genomic DNA was removed using RNase-Free DNase (Qiagen) and samples were cleaned up with the RNeasy MinElute Cleanup Kit (Qiagen) and sequenced by GenomeScan B.V. Leiden (The Netherlands) at a 20M read-depth.

Library Preparation
Samples were processed for Illumina using the NEBNext Ultra Directional RNA Library Prep Kit (NEB #E7420) according to manufacturer's. Briefly, rRNA was depleted from total RNA using the rRNA depletion kit (NEB# E6310). After fragmentation of the rRNA reduced RNA, a cDNA synthesis was performed in order to ligate with the sequencing adapters and PCR amplicification of the resulting product. Quality and yield after sample preparation was measured with the Fragment Analyzer. Size of the resulting products was consistent with the expected size distribution (a broad peak between 300-500 bp). Clustering and DNA sequencing using the

Mapping of the Reads
The quality of the reads in the fastq files was confirmed using FastQC version 0.11.4. The WBcel235 genome assembly was downloaded from wormbase (http://www.wormbase.org) and used as reference genome for the mapping. After successful mapping, counts per gene were extracted from the .SAM files with HTSeq version 0.9.1 (Anders et al., 2015). The -stranded=reverse setting was used, conform the NEB Ultra Directional RNA Library Prep Kit procedure.

Statistical Analysis
The statistical analysis was performed in R using DESeq2 version 1.16.1(Love et al., 2014).
DESeq2 models the raw counts with the Negative Binomial distribution and normalizes between samples by calculating size factors using the median ratio method (Anders & Huber, 2010).The statistical test is based on a generalized linear model (GLM) using the Negative Binomial model as an error distribution model. To more accurately model dispersion parameters the trend of dispersion to abundance is taken into account using an empirical Bayes procedure. The significance of the GLM coefficients are determined using a Wald test. The p-values are adjusted to correct for multiple testing. In the differential translational regulation analysis the fitted GLM took the following form: log(μ ) = β 0 + β 1 X + β 2 X + β 3 X X (1) Here the Wald test was performed on the interaction parameter 3 to infer significance. The log2 fold change calculated in this case corresponds to: Where in equation (1)

A
Representative polysome profiles of clk-1 mutants when lysate is normalized to total protein levels of 500ug. The monosomal peak and polysomal peaks are indicated.

B)
Quantification of polysome peak sizes. The fold change is represented compared to P1 of the clk-1 +WT. All peaks of clk-1+WT are significantly different (P < 0.05) from both clk-1+nuc and clk-1. No peaks were significantly different between clk-1 and clk-1+nuc.

A
Schematic representation of polysomal and total RNA from C. elegans mutants.
B Fold changes of differentially expressed genes in the total RNA of clk-1 vs clk-1 +WT plotted against fold changes in polysomal RNA of clk-1 vs clk-1 +WT . Colors of the individual data points correspond to the colors of the groups of genes in the Venn diagram in (C).

C
Venn diagram with number of genes exclusively upregulated (BLUE-GREEN) and downregulated (RED-ORANGE) in either polysomal RNA or total RNA of clk-1 strain compared to clk-1 +WT . Differential expressions in (B) and (C) are with a threshold adjusted p value < 0.01. D) Significant Cluster GO Enrichments (threshold Enrichment Score > 3) associated with the genes specifically up and downregulated in groups of genes in (C) (colors of the bars correspond again to the color of the groups in (C).

Figure 5 -Translation Efficiency (TE) of transcripts in clk-1 worms.
A Volcano plot of Log2 fold-change of TE of transcripts clk-1:clk-1+WT. The blue data points represent transcripts with high TE in clk-1 and low TE in clk-1+WT. The red data points represent transcripts that have low TE in clk-1 and high in clk-1+WT. Differentially translationally regulated genes in red and blue with threshold adjusted p value < 0.01.

B
Significant Cluster GO Enrichments (threshold Enrichment Score > 3) associated with significantly different TEs (colors of the bars correspond again to the data points in (A).

C
TE of individual transcripts involved in TOR pathway in clk-1+wt (left bar) clk-1 (middle bar) and the ratio (right bar). Colors of the ratio bars correspond again to the data points in (A).

D
Schematic overview of transcripts involved in TOR pathway that have different translational efficiencies in clk-1 vs. clk-1+WT represented in C and their involvement in longevity.

A
Representative polysome profiles of clk-1 mutants fed HT115 bacteria transformed with the empty vector or expressing taf-4 RNAi when lysate is normalized to total protein levels of 500ug. The monosomal peak and polysomal peaks are indicated.

B
Representative polysome profiles of clk-1 +WT mutants fed HT115 bacteria transformed with the empty vector or expressing taf-4 RNAi when lysate is normalized to total protein levels to total protein levels of 500ug. The monosomal peak and polysomal peaks are indicated.

C
Quantification of polysome peak sizes. The fold change is represented compared to P1 of the clk-1+WT controls.          Figure S1.

qPCR analysis of EIFs and RPs
Relative expression levels determined by qRT-PCR (Wild-type vs. clk-1(mq30)) normalized by expression of pmp-3 as reference gene.