A glycolytic enzyme, enolase, is recruited as a cofactor of tRNA targeting toward mitochondria in <i>Saccharomyces cerevisiae</i>

Entelis, Nina; Brandina, Irina; Kamenski, Piotr; Krasheninnikov, Igor A.; Martin, Robert P.; Tarassov, Ivan

doi:10.1101/gad.385706

Cited by 156 publications

(141 citation statements)

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“…It also involved tRNA transport to the mitochondria in yeast (13). It remains to be determined whether this newly discovered function is related in any way to the heat-stability of enolase.…”

Section: Features Of Heat-stable Proteins In E Colimentioning

confidence: 99%

Proteomic analysis of heat-stable proteins in Escherichia coli

Kwon¹,

Jung²,

Lim³

2008

BMB Reports

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Some proteins of E. coli are stable at temperatures significantly higher than 49 o C, the maximum temperature at which the organism can grow. The heat stability of such proteins would be a property which is inherent to their structures, or it might be acquired by evolution for their specialized functions. In this study, we describe the identification of 17 heat-stable proteins from E. coli. Approximately one-third of these proteins were recognized as having functions in the protection of other proteins against denaturation. These included chaperonin (GroEL and GroES), molecular chaperones (DnaK and FkpA) and peptidyl prolyl isomerases (trigger factor and FkpA). Another common feature was that five of these proteins (GroEL, GroES, Ahpc, RibH and ferritin) have been shown to form a macromolecular structure. These results indicated that the heat stability of certain proteins may have evolved for their specialized functions, allowing them to cope with harsh environments, including high temperatures. [BMB reports 2008; 41(2): 108-111]

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Section: Features Of Heat-stable Proteins In E Colimentioning

confidence: 99%

Proteomic analysis of heat-stable proteins in Escherichia coli

Kwon¹,

Jung²,

Lim³

2008

BMB Reports

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“…After the early observation of the presence of a cytoplasmic tRNA CUU Lys in Saccharomyces cerevisiae mitochondria (7), import of cytoplasmic tRNA CUG Gln was also demonstrated (8). Further studies showed that these tRNAs are imported by different mechanisms (8)(9)(10). The question of import into human mitochondria has never been addressed for its own sake.…”

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confidence: 99%

Mammalian mitochondria have the innate ability to import tRNAs by a mechanism distinct from protein import

Rubio

Rinehart

Krett

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

138

114

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Mitochondrial genomes generally encode a minimal set of tRNAs necessary for protein synthesis. However, a number of eukaryotes import tRNAs from the cytoplasm into their mitochondria. For instance, Saccharomyces cerevisiae imports cytoplasmic tRNA Gln into the mitochondrion without any added protein factors. Here, we examine the existence of a similar active tRNA import system in mammalian mitochondria. We have used subcellular RNA fractions from rat liver and human cells to perform RT-PCR with oligonucleotide primers specific for nucleus-encoded tRNA CUG Gln and tRNA UUG Gln species, and we show that these tRNAs are present in rat and human mitochondria in vivo. Import of in vitro transcribed tRNAs, but not of heterologous RNAs, into isolated mitochondria also demonstrates that this process is tRNA-specific and does not require the addition of cytosolic factors. Although this in vitro system requires ATP, it is resistant to inhibitors of the mitochondrial electrochemical gradient, a key component of protein import. tRNA Gln import into mammalian mitochondria proceeds by a mechanism distinct from protein import. We also show that both tRNA Gln species and a bacterial pre-tRNA Asp can be imported in vitro into mitochondria isolated from myoclonic epilepsy with ragged-red fiber cells if provided with sufficient ATP (2 mM). This work suggests that tRNA import is more widespread than previously thought and may be a universal trait of mitochondria. Mutations in mitochondrial tRNA genes have been associated with human disease; the tRNA import system described here could possibly be exploited for the manipulation of defective mitochondria.human ͉ MERFF D ifferent protein-synthesizing systems exist in the cytoplasm and organelles (mitochondria and chloroplasts) of eukaryotic cells. Reflecting the evolutionary origin of the organelle, the mitochondrial system is bacteria-like (1, 2). For instance, the tRNAs and aminoacyl-tRNA synthetases present in the mitochondria are closely related to their bacterial counterparts. The mitochondrial genome of higher eukaryotes encodes all of the tRNA species necessary for protein synthesis (3), whereas the aminoacyl-tRNA synthetases are nucleus-encoded and imported into the organelle. The mitochondrial protein-synthesizing system is important for the synthesis of a number of proteins for multienzyme complexes involved in oxidative phosphorylation (1). Since the original suggestion 40 years ago (4), tRNA import into mitochondria has been demonstrated in Tetrahymena, trypanosomatids, yeast, plants, and marsupials (reviewed in refs. 5 and 6). The detailed nature of the different tRNA import mechanisms is not yet known; however, ATP hydrolysis is always required. In the yeast system, the importance of some mitochondrial membrane proteins as well as of specific cytosolic proteins (enolase and lysyl-tRNA synthetase) has been established (reviewed in refs. 5 and 6). After the early observation of the presence of a cytoplasmic tRNA CUU Lys in Saccharomyces cerevisiae mitochondria (7), import o...

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“…This strongly suggests that the MLR proteins are translated next to mitochondria, although the reason for this remains obscure. In some cases, this phenomenon may favor the formation of nucleo-proteocomplexes in the vicinity of mitochondria, as for Msk1, the mitochondrial lysyl-tRNA synthetase, which guides the import of tRNA Lys toward mitochondria (Entelis et al, 2006). To describe the MLR phenomenon in more detail, we developed two highly sensitive methods to: 1) quantify, in vitro, the amount of mitochondrial-associated mRNA and 2) to visualize, in situ, the localization of some mRNA species.…”

Section: Introductionmentioning

confidence: 99%

Mitochondria-associated Yeast mRNAs and the Biogenesis of Molecular Complexes

Garcia

Darzacq

Delaveau

et al. 2007

MBoC

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The coherence of mitochondrial biogenesis relies on spatiotemporally coordinated associations of 800 -1000 proteins mostly encoded in the nuclear genome. We report the development of new quantitative analyses to assess the role of local protein translation in the construction of molecular complexes. We used real-time PCR to determine the cellular location of 112 mRNAs involved in seven mitochondrial complexes. Five typical cases were examined by an improved FISH protocol. The proteins produced in the vicinity of mitochondria (MLR proteins) were, almost exclusively, of prokaryotic origin and are key elements of the core construction of the molecular complexes; the accessory proteins were translated on free cytoplasmic polysomes. These two classes of proteins correspond, at least as far as intermembrane space (IMS) proteins are concerned, to two different import pathways. Import of MLR proteins involves both TOM and TIM23 complexes whereas non-MLR proteins only interact with the TOM complex. Site-specific translation loci, both outside and inside mitochondria, may coordinate the construction of molecular complexes composed of both nuclearly and mitochondrially encoded subunits. INTRODUCTIONMost mitochondrial proteins of eukaryotic cells are encoded by nuclear genes and synthesized by cytoplasmic ribosomes. However, a few proteins are encoded by the mitochondrial DNA and are translated inside mitochondria by bacterialtype ribosomes. The major mitochondrial import pathway of cytoplasmically translated proteins is now well understood (Koehler, 2004;Rehling et al., 2004). Although a posttranslational mechanism for import is widely accepted, it may concern only a limited class of proteins. Indeed, it was demonstrated 30 years ago that a subclass of cytoplasmic polysomes is bound to the surface of mitochondria (Kellems et al., 1975). Subsequently, experiments in yeast and human cells have suggested a cotranslational import process for some mitochondrial proteins (Fujiki and Verner, 1993;Mukhopadhyay et al., 2004). The evolutionary history of mitochondria might elucidate this apparent discrepancy between post-and cotranslational import processes. Phylogenetic studies of the yeast mitochondrial proteome have demonstrated a composite origin. It is estimated that half or more of the genes that code for the modern mitochondrial proteome originated directly from the host nuclear genome, and the other half are of bacterial origin, a consequence of a massive transfer of genes from the endosymbiont to the host nuclear genome (Marcotte et al., 2000;Karlberg et al., 2000). This symbiotic situation required the development of protein translocation machineries (translocases) in the mitochondrial membranes (Herrmann, 2003). Possibly, the two classes of nuclear genes coding for mitochondrial products may have used the same mitochondrial import pathway. However, a recent genomewide analysis (Marc et al., 2002) suggested a strong correlation between the bacterial origin of the genes and their locus specific translation on mitochondria-l...

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A glycolytic enzyme, enolase, is recruited as a cofactor of tRNA targeting toward mitochondria in Saccharomyces cerevisiae

Cited by 156 publications

References 56 publications

Proteomic analysis of heat-stable proteins in Escherichia coli

Proteomic analysis of heat-stable proteins in Escherichia coli

Mammalian mitochondria have the innate ability to import tRNAs by a mechanism distinct from protein import

Mitochondria-associated Yeast mRNAs and the Biogenesis of Molecular Complexes

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