Mitochondrial import of only one of three nuclear-encoded glutamine tRNAs in Tetrahymena thermophila.
C. P. Rusconi,Thomas R. Cech +1 more
TL;DR: It is concluded that tRNA(Gln)(UUG) is an imported tRNA in T.thermophila because it is a constituent of mitochondrial RNA fractions and is encoded only by nuclear genes, and because ectopically expressed tRNAs fractionates with mitochondria like its endogenous counterpart.
read more
Abstract: The mitochondrial genome of Tetrahymena does not appear to encode enough tRNAs to perform mitochondrial protein synthesis. It has therefore been proposed that nuclear-encoded tRNAs are imported into the mitochondria. T.thermophila has three major glutamine tRNAs: tRNA(Gln)(UUG), tRNA(Gln)(UUA) and tRNA(Gln)(CUA). Each of these tRNAs functions in cytosolic translation. However, due to differences between the Tetrahymena nuclear and mitochondrial genetic codes, only tRNA(Gln)(UUG) has the capacity to function in mitochondrial translation as well. Here we show that approximately 10-20% of the cellular complement of tRNA(Gln)(UUG) is present in mitochondrial RNA fractions, compared with 1% or less for the other two glutamine tRNAs. Furthermore, this glutamine tRNA is encoded only by a family of nuclear genes, the sequences of several of which are presented. Finally, when marked versions of tRNA(Gln)(UUG) and tRNA(Gln)(UUA) flanked by identical sequences are expressed in the macronucleus, only the former undergoes mitochondrial import; thus sequences within tRNA(Gln)(UUG) direct import. Because tRNA(Gln)(UUG) is a constituent of mitochondrial RNA fractions and is encoded only by nuclear genes, and because ectopically expressed tRNA(Gln)(UUG) fractionates with mitochondria like its endogenous counterpart, we conclude that it is an imported tRNA in T.thermophila.
read more
Chat with Paper
AI Agents for this Paper
Find similar papers on Google Scholar, PubMed and Arxiv
Write a critical review of this paper
Analyze citations of this paper to find unaddressed research gaps
Citations
Mitochondrial tRNA import and its consequences for mitochondrial translation.
TL;DR: Results in plants indicate that direct import of tRNAs may nevertheless require some components of the protein import machinery, which is not trivial and requires unique evolutionary adaptations.
A glycolytic enzyme, enolase, is recruited as a cofactor of tRNA targeting toward mitochondria in Saccharomyces cerevisiae
Nina Entelis,Irina Brandina,Piotr Kamenski,Igor A. Krasheninnikov,Robert P. Martin,Ivan Tarassov +5 more
TL;DR: The results indicate an alternative molecular chaperone function of glycolytic enzyme enolase in tRNA mitochondrial targeting, and propose a model suggesting that the cell exploits mitochondrial targeting of the enol enzyme in order to address the tRNA toward peri-mitochondrially synthesized preMsk1p.
Cell biology of Tetrahymena thermophila.
TL;DR: Tetrahymena thermophila can grow very well in a variety of axenic media, with generation times typically in the 2–3 hr range and optimally 1.4 hr, but even in otherwise optimal fully defined media, a minimal inoculum density typically is required to initiate exponential culture growth; at densities below this minimum, the cells die.
150
C to U editing of the anticodon of imported mitochondrial tRNA(Trp) allows decoding of the UGA stop codon in Leishmania tarentolae
TL;DR: It is shown that the mitochondrial tRNATrp undergoes a specific C to U nucleotide modification in the first position of the anticodon, which allows decoding of mitochondrial UGA codons as tryptophan.
The RNase P Associated with HeLa Cell Mitochondria Contains an Essential RNA Component Identical in Sequence to That of the Nuclear RNase P
Ram S. Puranam,Giuseppe Attardi +1 more
TL;DR: The available evidence indicates that the levels of mtRNase P detected in HeLa cells should be fully adequate to satisfy the mitochondrial tRNA synthesis requirements of these cells.
References
A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
TL;DR: This assay is very reproducible and rapid with the dye binding process virtually complete in approximately 2 min with good color stability for 1 hr with little or no interference from cations such as sodium or potassium nor from carbohydrates such as sucrose.
254.4K
CLUSTAL V: improved software for multiple sequence alignment.
TL;DR: The CLUSTAL package of multiple sequence alignment programs has been completely rewritten and many new features added, the main new features are the ability to store and reuse old alignments and to calculate phylogenetic trees after alignment.
2.6K
Base composition-independent hybridization in tetramethylammonium chloride: a method for oligonucleotide screening of highly complex gene libraries.
TL;DR: An oligonucleotide hybridization procedure has been developed that eliminates the preferential melting of A X T versus G X C base pairs, allowing the stringency of the hybridization to be controlled as a function of probe length only.
901
An unusual genetic code in nuclear genes of Tetrahymena
TL;DR: Comparison of the derived amino acid sequences of Tetrahymena histone H3 results in the surprising conclusion that TAA codes for glutamine, the first demonstration of a coding function for this termination codon of the "universal" code.
228