Selective importation of RNA into isolated mitochondria from Leishmania tarentolae

Rubio, Mary Anne T.; Li, Xuan; Yuzawa, Hiroko; Alfonzo, Juan D.; Simpson, Larry

doi:10.1017/s1355838200991519

Cited by 47 publications

(64 citation statements)

References 54 publications

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“…In all other cases known, tRNA import into mitochondria is an ATPrequiring process (8,21,23,24). We have tested the ATP requirements for tRNA Gln import into rat mitochondria and showed that import also requires ATP (Fig.…”

Section: In Vitro Import Into Mammalian Mitochondria Does Not Requirementioning

confidence: 99%

“…This antibiotic is known to collapse the membrane potential ⌬⌿ in the presence of potassium ions. Even when valinomycin is added in vast excess (100 times the concentration required to collapse ⌬⌿ in the presence of potassium chloride) (21), it has no effect on the tRNA import efficiency in rat mitochondria (Fig. 6C, compare lanes 1-4 with lane 8).…”

Section: Import Of Trna Into Mammalian Mitochondria Is Distinct From mentioning

confidence: 99%

“…In vitro import of tRNAs into isolated mitochondria has been demonstrated in a number of systems including plants, yeast, and trypanosomatids (17)(18)(19)(20)(21). We examined the in vitro import of various RNAs into isolated rat mitochondria by a nuclease protection assay (see Materials and Methods) (Fig.…”

Section: In Vitro Import Into Mammalian Mitochondria Does Not Requirementioning

confidence: 99%

“…A membrane potential is needed for the import of a number of tRNAs into isolated plant mitochondria (17) as well as import of tRNA Lys into yeast mitochondria (20), but it is not required in Leishmania or in the import of tRNA Gln into yeast mitochondria (8,21). We then performed import assays in the presence of the potassium ionophore valinomycin.…”

Section: Import Of Trna Into Mammalian Mitochondria Is Distinct From mentioning

confidence: 99%

“…Because the ⌬⌿ and the ⌬pH values are tightly linked, it is possible that in the presence of either inhibitor the electrochemical gradient is partially maintained by a concomitant A reaction similar to that in lane 6 of A was analyzed by a primer extension assay to map the 5Ј end of the products generated after import as described in ref. 21. Lanes 1 and 2 are negative control reactions performed in the absence of an RNA template or the absence of reverse transcriptase.…”

Section: Import Of Trna Into Mammalian Mitochondria Is Distinct From mentioning

confidence: 99%

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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.

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140

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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Section: In Vitro Import Into Mammalian Mitochondria Does Not Requirementioning

confidence: 99%

Section: Import Of Trna Into Mammalian Mitochondria Is Distinct From mentioning

confidence: 99%

Section: In Vitro Import Into Mammalian Mitochondria Does Not Requirementioning

confidence: 99%

Section: Import Of Trna Into Mammalian Mitochondria Is Distinct From mentioning

confidence: 99%

Section: Import Of Trna Into Mammalian Mitochondria Is Distinct From mentioning

confidence: 99%

See 3 more Smart Citations

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.

Self Cite

140

114

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Transfer RNA travels from the cytoplasm to organelles

Rubio

Hopper

2011

WIREs RNA

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Transfer RNAs (tRNAs) encoded by the nuclear genome are surprisingly dynamic. Although tRNAs function in protein synthesis occurring on cytoplasmic ribosomes, tRNAs can transit from the cytoplasm to the nucleus and then again return to the cytoplasm by a process known as the tRNA retrograde process. Subsets of the cytoplasmic tRNAs are also imported into mitochondria and function in mitochondrial protein synthesis. The numbers of tRNA species that are imported into mitchondria differ among organisms, ranging from just a few to the entire set needed to decode mitochondrially encoded mRNAs. For some tRNAs, import is dependent on the mitochondrial protein import machinery, whereas the majority of tRNA mitochondrial import is independent of this machinery. Although cytoplasmic proteins and proteins located on the mitochondrial surface participating in the tRNA import process have been described for several organisms, the identity of these proteins differ among organisms. Likewise, the tRNA determinants required for mitochondrial import differ among tRNA species and organisms. Here, we present an overview and discuss the current state of knowledge regarding the mechanisms involved in the tRNA retrograde process and continue with an overview of tRNA import into mitochondria. Finally, we highlight areas of future research to understand the function and regulation of movement of tRNAs between the cytoplasm and organelles.

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RNase P from Organelles

Vioque

2009

Ribonuclease P

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Selective importation of RNA into isolated mitochondria from Leishmania tarentolae

Cited by 47 publications

References 54 publications

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

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

Transfer RNA travels from the cytoplasm to organelles

RNase P from Organelles

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