scholarly journals METTL15 interacts with the assembly intermediate of murine mitochondrial small ribosomal subunit to form m4C840 12S rRNA residue

2020 ◽  
Vol 48 (14) ◽  
pp. 8022-8034 ◽  
Author(s):  
Ivan Laptev ◽  
Ekaterina Shvetsova ◽  
Sergey Levitskii ◽  
Marina Serebryakova ◽  
Maria Rubtsova ◽  
...  
Keyword(s):  
Protein Biosynthesis ◽  
Mitochondrial Protein ◽  
Ribosomal Subunit ◽  
12S Rrna ◽  
Small Ribosomal Subunit ◽  
Mitochondrial Ribosomes ◽  
Murine Cell Line ◽  
Assembly Factor ◽  
Mitochondrial 12S Rrna ◽  
Assembly Intermediate

Abstract Mammalian mitochondrial ribosomes contain a set of modified nucleotides, which is distinct from that of the cytosolic ribosomes. Nucleotide m4C840 of the murine mitochondrial 12S rRNA is equivalent to the dimethylated m4Cm1402 residue of Escherichia coli 16S rRNA. Here we demonstrate that mouse METTL15 protein is responsible for the formation of m4C residue of the 12S rRNA. Inactivation of Mettl15 gene in murine cell line perturbs the composition of mitochondrial protein biosynthesis machinery. Identification of METTL15 interaction partners revealed that the likely substrate for this RNA methyltransferase is an assembly intermediate of the mitochondrial small ribosomal subunit containing an assembly factor RBFA.

scholarly journals Structural consequences of the interaction of RbgA with a 50S ribosomal subunit assembly intermediate

2019 ◽  
Vol 47 (19) ◽  
pp. 10414-10425 ◽  
Author(s):  
Amal Seffouh ◽  
Nikhil Jain ◽  
Dushyant Jahagirdar ◽  
Kaustuv Basu ◽  
Aida Razi ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Large Subunit ◽  
Ribosomal Subunit ◽  
Catalytic Residue ◽  
Gtp Hydrolysis ◽  
Subunit Assembly ◽  
Cryo Electron Microscopy ◽  
Assembly Factor ◽  
Assembly Intermediate ◽  
Immature Particle

Abstract Bacteria harbor a number GTPases that function in the assembly of the ribosome and are essential for growth. RbgA is one of these GTPases and is required for the assembly of the 50S subunit in most bacteria. Homologs of this protein are also implicated in the assembly of the large subunit of the mitochondrial and eukaryotic ribosome. We present here the cryo-electron microscopy structure of RbgA bound to a Bacillus subtilis 50S subunit assembly intermediate (45SRbgA particle) that accumulates in cells upon RbgA depletion. Binding of RbgA at the P site of the immature particle stabilizes functionally important rRNA helices in the A and P-sites, prior to the completion of the maturation process of the subunit. The structure also reveals the location of the highly conserved N-terminal end of RbgA containing the catalytic residue Histidine 9. The derived model supports a mechanism of GTP hydrolysis, and it shows that upon interaction of RbgA with the 45SRbgA particle, Histidine 9 positions itself near the nucleotide potentially acting as the catalytic residue with minimal rearrangements. This structure represents the first visualization of the conformational changes induced by an assembly factor in a bacterial subunit intermediate.

scholarly journals Cbp3–Cbp6 interacts with the yeast mitochondrial ribosomal tunnel exit and promotes cytochrome b synthesis and assembly

2011 ◽  
Vol 193 (6) ◽  
pp. 1101-1114 ◽  
Author(s):  
Steffi Gruschke ◽  
Kirsten Kehrein ◽  
Katharina Römpler ◽  
Kerstin Gröne ◽  
Lars Israel ◽  
...  
Keyword(s):  
Cytochrome B ◽  
Genetic System ◽  
The Other ◽  
Bc1 Complex ◽  
Mitochondrial Ribosomes ◽  
Ribosomal Tunnel ◽  
Assembly Factor ◽  
Assembly Intermediate ◽  
The One ◽  
Essential Subunit

Mitochondria contain their own genetic system to express a small number of hydrophobic polypeptides, including cytochrome b, an essential subunit of the bc1 complex of the respiratory chain. In this paper, we show in yeast that Cbp3, a bc1 complex assembly factor, and Cbp6, a regulator of cytochrome b translation, form a complex that associates with the polypeptide tunnel exit of mitochondrial ribosomes and that exhibits two important functions in the biogenesis of cytochrome b. On the one hand, the interaction of Cbp3 and Cbp6 with mitochondrial ribosomes is necessary for efficient translation of cytochrome b transcript. On the other hand, the Cbp3–Cbp6 complex interacts directly with newly synthesized cytochrome b in an assembly intermediate that is not ribosome bound and that contains the assembly factor Cbp4. Our results suggest that synthesis of cytochrome b occurs preferentially on those ribosomes that have the Cbp3–Cbp6 complex bound to their tunnel exit, an arrangement that may ensure tight coordination of cytochrome b synthesis and assembly.

Var 1 is associated with the small ribosomal subunit of mitochondrial ribosomes in yeast

1979 ◽  
Vol 174 (3) ◽  
pp. 339-342 ◽  
Author(s):  
Gert S. P. Groot ◽  
Thomas L. Mason ◽  
Nel Van Harten-Loosbroek
Keyword(s):  
Ribosomal Subunit ◽  
Small Ribosomal Subunit ◽  
Mitochondrial Ribosomes

scholarly journals The human RNA-binding protein RBFA promotes the maturation of the mitochondrial ribosome

2017 ◽  
Vol 474 (13) ◽  
pp. 2145-2158 ◽  
Author(s):  
Agata Rozanska ◽  
Ricarda Richter-Dennerlein ◽  
Joanna Rorbach ◽  
Fei Gao ◽  
Richard J. Lewis ◽  
...  
Keyword(s):  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Ribosomal Subunit ◽  
Small Subunit ◽  
12S Rrna ◽  
Mitochondrial Rna ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Rrna Species

Accurate assembly and maturation of human mitochondrial ribosomes is essential for synthesis of the 13 polypeptides encoded by the mitochondrial genome. This process requires the correct integration of 80 proteins, 1 mt (mitochondrial)-tRNA and 2 mt-rRNA species, the latter being post-transcriptionally modified at many sites. Here, we report that human ribosome-binding factor A (RBFA) is a mitochondrial RNA-binding protein that exerts crucial roles in mitoribosome biogenesis. Unlike its bacterial orthologue, RBFA associates mainly with helices 44 and 45 of the 12S rRNA in the mitoribosomal small subunit to promote dimethylation of two highly conserved consecutive adenines. Characterization of RBFA-depleted cells indicates that this dimethylation is not a prerequisite for assembly of the small ribosomal subunit. However, the RBFA-facilitated modification is necessary for completing mt-rRNA maturation and regulating association of the small and large subunits to form a functional monosome implicating RBFA in the quality control of mitoribosome formation.

scholarly journals Analysis of Leigh Syndrome Mutations in the Yeast SURF1 Homolog Reveals a New Member of the Cytochrome Oxidase Assembly Factor Family

2010 ◽  
Vol 30 (18) ◽  
pp. 4480-4491 ◽  
Author(s):  
Megan Bestwick ◽  
Mi-Young Jeong ◽  
Oleh Khalimonchuk ◽  
Hyung Kim ◽  
Dennis R. Winge
Keyword(s):  
Respiratory Function ◽  
Functional Role ◽  
Mitochondrial Protein ◽  
Leigh Syndrome ◽  
Intermembrane Space ◽  
Assembly Factor ◽  
Allele Specific ◽  
Assembly Intermediate ◽  
Yeast Homolog

ABSTRACT Three missense SURF1 mutations identified in patients with Leigh syndrome (LS) were evaluated in the yeast homolog Shy1 protein. Introduction of two of the Leigh mutations, F249T and Y344D, in Shy1 failed to significantly attenuate the function of Shy1 in cytochrome c oxidase (CcO) biogenesis as seen with the human mutations. In contrast, a G137E substitution in Shy1 results in a nonfunctional protein conferring a CcO deficiency. The G137E Shy1 mutant phenocopied shy1Δ cells in impaired Cox1 hemylation and low mitochondrial copper. A genetic screen for allele-specific suppressors of the G137E Shy1 mutant revealed Coa2, Cox10, and a novel factor designated Coa4. Coa2 and Cox10 are previously characterized CcO assembly factors. Coa4 is a twin CX9C motif mitochondrial protein localized in the intermembrane space and associated with the inner membrane. Cells lacking Coa4 are depressed in CcO activity but show no impairment in Cox1 maturation or formation of the Shy1-stabilized Cox1 assembly intermediate. To glean insights into the functional role of Coa4 in CcO biogenesis, an unbiased suppressor screen of coa4Δ cells was conducted. Respiratory function of coa4Δ cells was restored by the overexpression of CYC1 encoding cytochrome c. Cyc1 is known to be important at an ill-defined step in the assembly and/or stability of CcO. This new link to Coa4 may begin to further elucidate the role of Cyc1 in CcO biogenesis.

scholarly journals The human mitochondrial 12S rRNA m4C methyltransferase METTL15 is required for mitochondrial function

2020 ◽  
Vol 295 (25) ◽  
pp. 8505-8513 ◽  
Author(s):  
Hao Chen ◽  
Zhennan Shi ◽  
Jiaojiao Guo ◽  
Kao-jung Chang ◽  
Qianqian Chen ◽  
...  
Keyword(s):  
Mitochondrial Function ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Small Subunit ◽  
12S Rrna ◽  
Mitochondrial Rna ◽  
Small Subunit Rrna ◽  
Mitochondrial Ribosomes

Mitochondrial DNA gene expression is coordinately regulated both pre- and post-transcriptionally, and its perturbation can lead to human pathologies. Mitochondrial rRNAs (mt-rRNAs) undergo a series of nucleotide modifications after release from polycistronic mitochondrial RNA precursors, which is essential for mitochondrial ribosomal biogenesis. Cytosine N4-methylation (m4C) at position 839 (m4C839) of the 12S small subunit mt-rRNA was identified decades ago; however, its biogenesis and function have not been elucidated in detail. Here, using several approaches, including immunofluorescence, RNA immunoprecipitation and methylation assays, and bisulfite mapping, we demonstrate that human methyltransferase-like 15 (METTL15), encoded by a nuclear gene, is responsible for 12S mt-rRNA methylation at m4C839 both in vivo and in vitro. We tracked the evolutionary history of RNA m4C methyltransferases and identified a difference in substrate preference between METTL15 and its bacterial ortholog rsmH. Additionally, unlike the very modest impact of a loss of m4C methylation in bacterial small subunit rRNA on the ribosome, we found that METTL15 depletion results in impaired translation of mitochondrial protein-coding mRNAs and decreases mitochondrial respiration capacity. Our findings reveal that human METTL15 is required for mitochondrial function, delineate the evolution of methyltransferase substrate specificities and modification patterns in rRNA, and highlight a differential impact of m4C methylation on prokaryotic ribosomes and eukaryotic mitochondrial ribosomes.

scholarly journals Dual function of GTPBP6 in biogenesis and recycling of human mitochondrial ribosomes

2020 ◽  
Vol 48 (22) ◽  
pp. 12929-12942 ◽  
Author(s):  
Elena Lavdovskaia ◽  
Kärt Denks ◽  
Franziska Nadler ◽  
Emely Steube ◽  
Andreas Linden ◽  
...  
Keyword(s):  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
Dual Function ◽  
Large Ribosomal Subunit ◽  
Ribosome Recycling Factor ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosomes ◽  
Assembly Intermediate

Abstract Translation and ribosome biogenesis in mitochondria require auxiliary factors that ensure rapid and accurate synthesis of mitochondrial proteins. Defects in translation are associated with oxidative phosphorylation deficiency and cause severe human diseases, but the exact roles of mitochondrial translation-associated factors are not known. Here we identify the functions of GTPBP6, a homolog of the bacterial ribosome-recycling factor HflX, in human mitochondria. Similarly to HflX, GTPBP6 facilitates the dissociation of ribosomes in vitro and in vivo. In contrast to HflX, GTPBP6 is also required for the assembly of mitochondrial ribosomes. GTPBP6 ablation leads to accumulation of late assembly intermediate(s) of the large ribosomal subunit containing ribosome biogenesis factors MTERF4, NSUN4, MALSU1 and the GTPases GTPBP5, GTPBP7 and GTPBP10. Our data show that GTPBP6 has a dual function acting in ribosome recycling and biogenesis. These findings contribute to our understanding of large ribosomal subunit assembly as well as ribosome recycling pathway in mitochondria.

scholarly journals YBEY is an essential biogenesis factor for mitochondrial ribosomes

2019 ◽  
Author(s):  
Sabrina Summer ◽  
Anna Smirnova ◽  
Alessandro Gabriele ◽  
Ursula Toth ◽  
Fasemore Mandela ◽  
...  
Keyword(s):  
16S Rrna ◽  
Ribosome Biogenesis ◽  
Specific Interaction ◽  
Ribosomal Subunit ◽  
Small Subunit ◽  
12S Rrna ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Abnormal Mitochondria

ABSTRACTRibosome biogenesis requires numerous trans-acting factors, some of which are deeply conserved. In Bacteria, the endoribonuclease YbeY is believed to be involved in 16S rRNA 3’-end processing and its loss was associated with ribosomal abnormalities. In Eukarya, YBEY appears to generally localize to mitochondria (or chloroplasts). Here we show that the deletion of human YBEY results in a severe respiratory deficiency and morphologically abnormal mitochondria as an apparent consequence of impaired mitochondrial translation. Reduced stability of 12S rRNA and the deficiency of several proteins of the small ribosomal subunit in YBEY knockout cells pointed towards a defect in mitochondrial ribosome biogenesis. The specific interaction of mitoribosomal protein uS11m with YBEY suggests that the latter recruits uS11m to the nascent small subunit in its late assembly stage. This scenario shows similarities with final stages of cytosolic ribosome biogenesis, and may represent a late checkpoint before the mitoribosome engages in translation.

scholarly journals Cryo-EM structure of yeast 90S preribosome at 3.4 Å resolution

2020 ◽  
Author(s):  
Yifei Du ◽  
Weidong An ◽  
Keqiong Ye
Keyword(s):  
18S Rrna ◽  
Ribosomal Subunit ◽  
Small Ribosomal Subunit ◽  
Central Domain ◽  
Closed Conformation ◽  
Open Conformation ◽  
Assembly Mechanism ◽  
High Resolution Structure ◽  
Assembly Intermediate ◽  
Resolution Structure

AbstractPreviously, we determined a cryo-EM structure of Saccharomyces cerevisiae 90S preribosome obtained after depletion of the RNA helicase Mtr4 at 4.5 Å resolution (Sun et al., 2017). The 90S preribosome is an early assembly intermediate of small ribosomal subunit. Here, the structure was improved to 3.4 Å resolution and reveals many previously unresolved structures and interactions, in particular around the central domain of 18S rRNA. The central domain adopts a closed conformation in our structure, in contrast to an open conformation in another high-resolution structure of S. cerevisiae 90S. The new model of 90S would serve as a better reference for investigation of the assembly mechanism of small ribosomal subunit.

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