scholarly journals Mitochondrial tRNA import – the challenge to understand has just begun

2009 ◽  
Vol 390 (8) ◽  
Author(s):  
Juan D. Alfonzo ◽  
Dieter Söll
Keyword(s):  
Oxidative Phosphorylation ◽  
Mitochondrial Genomes ◽  
Trna Genes ◽  
Mitochondrial Membranes ◽  
Mitochondrial Translation ◽  
Mitochondrial Trna ◽  
Trna Import ◽  
Made In ◽  
In Cells

Abstract Mitochondrial translation is important for the synthesis of proteins involved in oxidative phosphorylation, which yields the bulk of the ATP made in cells. During evolution most mitochondria-containing organisms have lost tRNA genes from their mitochondrial genomes. Thus, to support the essential process of nuanced mitochondrial translation, mechanisms to actively transport tRNAs from the cytoplasm across the mitochondrial membranes into the mitochondrion have evolved. Here, we review the currently known tRNA import mechanisms, comment on recent discoveries of various import factors, and suggest a rationale for forces that lie behind the evolution of mitochondrial tRNA import.

Posttranscriptional modifications in mitochondrial tRNA and its implication in mitochondrial translation and disease

2020 ◽  
Vol 168 (5) ◽  
pp. 435-444
Author(s):  
Tomizawa Kazuhito ◽  
Fan-Yan Wei
Keyword(s):  
Mitochondrial Diseases ◽  
Protein Translation ◽  
Fundamental Aspect ◽  
Trna Genes ◽  
Mitochondrial Translation ◽  
Mitochondrial Trna ◽  
Genes Encoding ◽  
Stability Structure ◽  
Life Threatening ◽  
Mrna Binding

Abstract A fundamental aspect of mitochondria is that they possess DNA and protein translation machinery. Mitochondrial DNA encodes 22 tRNAs that translate mitochondrial mRNAs to 13 polypeptides of respiratory complexes. Various chemical modifications have been identified in mitochondrial tRNAs via complex enzymatic processes. A growing body of evidence has demonstrated that these modifications are essential for translation by regulating tRNA stability, structure and mRNA binding, and can be dynamically regulated by the metabolic environment. Importantly, the hypomodification of mitochondrial tRNA due to pathogenic mutations in mitochondrial tRNA genes or nuclear genes encoding modifying enzymes can result in life-threatening mitochondrial diseases in humans. Thus, the mitochondrial tRNA modification is a fundamental mechanism underlying the tight regulation of mitochondrial translation and is essential for life. In this review, we focus on recent findings on the physiological roles of 5-taurinomethyl modification (herein referred as taurine modification) in mitochondrial tRNAs. We summarize the findings in human patients and animal models with a deficiency of taurine modifications and provide pathogenic links to mitochondrial diseases. We anticipate that this review will help understand the complexity of mitochondrial biology and disease.

scholarly journals Mutational Screening for Mitochondrial tRNA Mutations in 150 Children with High Myopia

2021 ◽  
Vol 31 (5) ◽  
Author(s):  
Tian Xia ◽  
Ying Pang ◽  
Huimin Xiong
Keyword(s):  
Mitochondrial Dysfunction ◽  
High Myopia ◽  
Phenotypic Expression ◽  
Active Role ◽  
Unknown Etiology ◽  
Trna Genes ◽  
Mitochondrial Translation ◽  
Mitochondrial Trna ◽  
Pathogenic Variants ◽  
Mutational Screening

Background: Myopia is a very common eye disease with an unknown etiology. Increasing evidence shows that mitochondrial dysfunction plays an active role in the pathogenesis and progression of this disease. Objectives: The purpose of this study was to analyze the relationship between mitochondrial tRNA (mt-tRNA) variants and high myopia (HM). Methods: The entire mt-tRNA genes of 150 children with HM, as well as 100 healthy subjects, were PCR-amplified and sequenced. To assess the pathogenicity, we used the phylogenetic conservation analysis and pathogenicity scoring system. Results: We identified six candidate pathogenic variants: tRNALeu (UUR) T3290C, tRNAIle A4317G, tRNAAla G5591A, tRNASer (UCN) T7501C, tRNAHis T12201C, and tRNAThr G15915A. However, these variants were not identified in controls. Further phylogenetic analysis revealed that these variants occurred at the positions, which were very evolutionarily conserved and may have structural-functional impacts on the tRNAs. Subsequently, these variants may lead to the impairment of mitochondrial translation and aggravated mitochondrial dysfunction, which play an active role in the phenotypic expression of HM. Conclusions: Our results suggested that variants in mt-tRNA genes were the risk factors for HM, which provided valuable information for the early detection and prevention of HM.

scholarly journals tRNAs and proteins use the same import channel for translocation across the mitochondrial outer membrane of trypanosomes

2017 ◽  
Vol 114 (37) ◽  
pp. E7679-E7687 ◽  
Author(s):  
Moritz Niemann ◽  
Anke Harsman ◽  
Jan Mani ◽  
Christian D. Peikert ◽  
Silke Oeljeklaus ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Protein Import ◽  
Single Channel ◽  
Mitochondrial Outer Membrane ◽  
Trna Genes ◽  
Intermembrane Space ◽  
Mitochondrial Trna ◽  
Trna Import ◽  
Single Channel Currents

Mitochondrial tRNA import is widespread, but the mechanism by which tRNAs are imported remains largely unknown. The mitochondrion of the parasitic protozoan Trypanosoma brucei lacks tRNA genes, and thus imports all tRNAs from the cytosol. Here we show that in T. brucei in vivo import of tRNAs requires four subunits of the mitochondrial outer membrane protein translocase but not the two receptor subunits, one of which is essential for protein import. The latter shows that it is possible to uncouple mitochondrial tRNA import from protein import. Ablation of the intermembrane space domain of the translocase subunit, archaic translocase of the outer membrane (ATOM)14, on the other hand, while not affecting the architecture of the translocase, impedes both protein and tRNA import. A protein import intermediate arrested in the translocation channel prevents both protein and tRNA import. In the presence of tRNA, blocking events of single-channel currents through the pore formed by recombinant ATOM40 were detected in electrophysiological recordings. These results indicate that both types of macromolecules use the same import channel across the outer membrane. However, while tRNA import depends on the core subunits of the protein import translocase, it does not require the protein import receptors, indicating that the two processes are not mechanistically linked.

scholarly journals tRNA import across the mitochondrial inner membrane in T. brucei requires TIM subunits but is independent of protein import

2020 ◽  
Vol 48 (21) ◽  
pp. 12269-12281
Author(s):  
Shikha Shikha ◽  
Jonathan L Huot ◽  
André Schneider ◽  
Moritz Niemann
Keyword(s):  
Protein Import ◽  
Protein Translocation ◽  
Matrix Proteins ◽  
Trna Genes ◽  
Mitochondrial Trna ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Trna Import ◽  
Inner Membrane Protein

Abstract Mitochondrial tRNA import is widespread, but mechanistic insights of how tRNAs are translocated across mitochondrial membranes remain scarce. The parasitic protozoan T. brucei lacks mitochondrial tRNA genes. Consequently, it imports all organellar tRNAs from the cytosol. Here we investigated the connection between tRNA and protein translocation across the mitochondrial inner membrane. Trypanosomes have a single inner membrane protein translocase that consists of three heterooligomeric submodules, which all are required for import of matrix proteins. In vivo depletion of individual submodules shows that surprisingly only the integral membrane core module, including the protein import pore, but not the presequence-associated import motor are required for mitochondrial tRNA import. Thus we could uncouple import of matrix proteins from import of tRNAs even though both substrates are imported into the same mitochondrial subcompartment. This is reminiscent to the outer membrane where the main protein translocase but not on-going protein translocation is required for tRNA import. We also show that import of tRNAs across the outer and inner membranes are coupled to each other. Taken together, these data support the ‘alternate import model’, which states that tRNA and protein import while mechanistically independent use the same translocation pores but not at the same time.

scholarly journals Rapid shifts in mitochondrial tRNA import in a plant lineage with extensive mitochondrial tRNA gene loss

2021 ◽  
Author(s):  
Jessica Marie Warren ◽  
Thalia Salinas-Giegé ◽  
Deborah A. Triant ◽  
Douglas R. Taylor ◽  
Laurence Drouard ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Gene Loss ◽  
Trna Gene ◽  
Flowering Plant ◽  
Trna Genes ◽  
Evolutionary Divergence ◽  
Mitochondrial Trna ◽  
Trna Import ◽  
History Of ◽  
Mitochondrial Trna Gene

In most eukaryotes, transfer RNAs (tRNAs) are one of the very few classes of genes remaining in the mitochondrial genome, but some mitochondria have lost these vestiges of their prokaryotic ancestry. Sequencing of mitogenomes from the flowering plant genus Silene previously revealed a large range in tRNA gene content, suggesting rapid and ongoing gene loss/replacement. Here, we use this system to test longstanding hypotheses about how mitochondrial tRNA genes are replaced by importing nuclear-encoded tRNAs. We traced the evolutionary history of these gene loss events by sequencing mitochondrial genomes from key outgroups (Agrostemma githago and Silene [=Lychnis] chalcedonica). We then performed the first global sequencing of purified plant mitochondrial tRNA populations to characterize the expression of mitochondrial-encoded tRNAs and the identity of imported nuclear-encoded tRNAs. We also confirmed the utility of high-throughput sequencing methods for the detection of tRNA import by sequencing mitochondrial tRNA populations in a species (Solanum tuberosum) with known tRNA trafficking patterns. Mitochondrial tRNA sequencing in Silene revealed substantial shifts in the abundance of some nuclear-encoded tRNAs in conjunction with their recent history of mt-tRNA gene loss and surprising cases where tRNAs with anticodons still encoded in the mitochondrial genome also appeared to be imported. These data suggest that nuclear-encoded counterparts are likely replacing mitochondrial tRNAs even in systems with recent mitochondrial tRNA gene loss, and the redundant import of a nuclear-encoded tRNA may provide a mechanism for functional replacement between translation systems separated by billions of years of evolutionary divergence.

scholarly journals Evidence for Import of a Lysyl-tRNA into Marsupial Mitochondria

2001 ◽  
Vol 12 (9) ◽  
pp. 2688-2698 ◽  
Author(s):  
Marion Dörner ◽  
Markus Altmann ◽  
Svante Pääbo ◽  
Mario Mörl
Keyword(s):  
Secondary Structure ◽  
Rna Editing ◽  
Trna Gene ◽  
Nuclear Genome ◽  
Mitochondrial Genomes ◽  
Primary Sequence ◽  
Mitochondrial Trna ◽  
Trna Import ◽  
Mitochondrial Trna Gene

The mitochondrial tRNA gene for lysine was analyzed in 11 different marsupial mammals. Whereas its location is conserved when compared with other vertebrate mitochondrial genomes, its primary sequence and inferred secondary structure are highly unusual and variable. For example, eight species lack the expected anticodon. Because the corresponding transcripts are not altered by any RNA-editing mechanism, the lysyl-tRNA gene seems to represent a mitochondrial pseudogene. Purification of marsupial mitochondria and in vitro aminoacylation of isolated tRNAs with lysine, followed by analysis of aminoacylated tRNAs, show that a nuclear-encoded tRNALys is associated with marsupial mitochondria. We conclude that a functional tRNALys encoded in the nuclear genome is imported into mitochondria in marsupials. Thus, tRNA import is not restricted to plant, yeast, and protozoan mitochondria but also occurs also in mammals.

scholarly journals Mitochondrial Translation and Beyond: Processes Implicated in Combined Oxidative Phosphorylation Deficiencies

2010 ◽  
Vol 2010 ◽  
pp. 1-24 ◽  
Author(s):  
Paulien Smits ◽  
Jan Smeitink ◽  
Lambert van den Heuvel
Keyword(s):  
Oxidative Phosphorylation ◽  
Genetic Defect ◽  
Human Diseases ◽  
Mitochondrial Genomes ◽  
Present Communication ◽  
Mitochondrial Translation ◽  
Easy Task ◽  
Genetic Causes ◽  
Oxphos System ◽  
Enzyme Complexes

Mitochondrial disorders are a heterogeneous group of often multisystemic and early fatal diseases, which are amongst the most common inherited human diseases. These disorders are caused by defects in the oxidative phosphorylation (OXPHOS) system, which comprises five multisubunit enzyme complexes encoded by both the nuclear and the mitochondrial genomes. Due to the multitude of proteins and intricacy of the processes required for a properly functioning OXPHOS system, identifying the genetic defect that underlies an OXPHOS deficiency is not an easy task, especially in the case of combined OXPHOS defects. In the present communication we give an extensive overview of the proteins and processes (in)directly involved in mitochondrial translation and the biogenesis of the OXPHOS system and their roles in combined OXPHOS deficiencies. This knowledge is important for further research into the genetic causes, with the ultimate goal to effectively prevent and cure these complex and often devastating disorders.

scholarly journals Rapid Shifts in Mitochondrial tRNA Import in a Plant Lineage with Extensive Mitochondrial tRNA Gene Loss

2021 ◽  
Author(s):  
Jessica M Warren ◽  
Thalia Salinas-Giegé ◽  
Deborah A Triant ◽  
Douglas R Taylor ◽  
Laurence Drouard ◽  
...  
Keyword(s):  
Mitochondrial Genome ◽  
Gene Loss ◽  
Trna Gene ◽  
Flowering Plant ◽  
Trna Genes ◽  
Evolutionary Divergence ◽  
Mitochondrial Trna ◽  
Trna Import ◽  
History Of ◽  
Mitochondrial Trna Gene

Abstract In most eukaryotes, transfer RNAs (tRNAs) are one of the very few classes of genes remaining in the mitochondrial genome, but some mitochondria have lost these vestiges of their prokaryotic ancestry. Sequencing of mitogenomes from the flowering plant genus Silene previously revealed a large range in tRNA gene content, suggesting rapid and ongoing gene loss/replacement. Here, we use this system to test longstanding hypotheses about how mitochondrial tRNA genes are replaced by importing nuclear-encoded tRNAs. We traced the evolutionary history of these gene loss events by sequencing mitochondrial genomes from key outgroups (Agrostemma githago and Silene [=Lychnis] chalcedonica). We then performed the first global sequencing of purified plant mitochondrial tRNA populations to characterize the expression of mitochondrial-encoded tRNAs and the identity of imported nuclear-encoded tRNAs. We also confirmed the utility of high-throughput sequencing methods for the detection of tRNA import by sequencing mitochondrial tRNA populations in a species (Solanum tuberosum) with known tRNA trafficking patterns. Mitochondrial tRNA sequencing in Silene revealed substantial shifts in the abundance of some nuclear-encoded tRNAs in conjunction with their recent history of mt-tRNA gene loss and surprising cases where tRNAs with anticodons still encoded in the mitochondrial genome also appeared to be imported. These data suggest that nuclear-encoded counterparts are likely replacing mitochondrial tRNAs even in systems with recent mitochondrial tRNA gene loss, and the redundant import of a nuclear-encoded tRNA may provide a mechanism for functional replacement between translation systems separated by billions of years of evolutionary divergence.

scholarly journals Mitochondrial genome evolution in pelagophyte algae

2021 ◽  
Author(s):  
Shannon J Sibbald ◽  
Maggie Lawton ◽  
John M Archibald
Keyword(s):  
Mitochondrial Genome ◽  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
23S Rrna ◽  
Mitochondrial Genomes ◽  
Trna Genes ◽  
Unique Region ◽  
Long Read ◽  
Genomic Studies ◽  
Aureoumbra Lagunensis

Abstract The Pelagophyceae are marine stramenopile algae that include Aureoumbra lagunensis and Aureococcus anophagefferens, two microbial species notorious for causing harmful algal blooms. Despite their ecological significance, relatively few genomic studies of pelagophytes have been carried out. To improve understanding of the biology and evolution of pelagophyte algae, we sequenced complete mitochondrial genomes for A. lagunensis (CCMP1510), Pelagomonas calceolata (CCMP1756) and five strains of A. anophagefferens (CCMP1707, CCMP1708, CCMP1850, CCMP1984 and CCMP3368) using Nanopore long-read sequencing. All pelagophyte mitochondrial genomes assembled into single, circular mapping contigs between 39,376 base-pairs (bp) (P. calceolata) and 55,968 bp (A. lagunensis) in size. Mitochondrial genomes for the five A. anophagefferens strains varied slightly in length (42,401 bp—42,621 bp) and were 99.4%-100.0% identical. Gene content and order was highly conserved between the A. anophagefferens and P. calceolata genomes, with the only major difference being a unique region in A. anophagefferens containing DNA adenine and cytosine methyltransferase (dam/dcm) genes that appear to be the product of lateral gene transfer from a prokaryotic or viral donor. While the A. lagunensis mitochondrial genome shares seven distinct syntenic blocks with the other pelagophyte genomes, it has a tandem repeat expansion comprising ∼40% of its length, and lacks identifiable rps19 and glycine tRNA genes. Laterally acquired self-splicing introns were also found in the 23S rRNA (rnl) gene of P. calceolata and the coxI gene of the five A. anophagefferens genomes. Overall, these data provide baseline knowledge about the genetic diversity of bloom-forming pelagophytes relative to non-bloom-forming species.

Sign in / Sign up

Export Citation Format

Share Document