scholarly journals The conserved interaction of C7orf30 with MRPL14 promotes biogenesis of the mitochondrial large ribosomal subunit and mitochondrial translation

2013 ◽  
Vol 24 (3) ◽  
pp. 184-193 ◽  
Author(s):  
Stephen Fung ◽  
Tamiko Nishimura ◽  
Florin Sasarman ◽  
Eric A. Shoubridge
Keyword(s):  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
Large Family ◽  
Large Ribosomal Subunit ◽  
Mitochondrial Translation ◽  
Interacting Protein ◽  
Mitochondrial Ribosome ◽  
Essential Components ◽  
Translation Apparatus ◽  
Interfering Rna

Mammalian mitochondria harbor a dedicated translation apparatus that is required for the synthesis of 13 mitochondrial DNA (mtDNA)-encoded polypeptides, all of which are essential components of the oxidative phosphorylation (OXPHOS) complexes. Little is known about the mechanism of assembly of the mitoribosomes that catalyze this process. Here we show that C7orf30, a member of the large family of DUF143 proteins, associates with the mitochondrial large ribosomal subunit (mt-LSU). Knockdown of C7orf30 by short hairpin RNA (shRNA) does not alter the sedimentation profile of the mt-LSU, but results in the depletion of several mt-LSU proteins and decreased monosome formation. This leads to a mitochondrial translation defect, involving the majority of mitochondrial polypeptides, and a severe OXPHOS assembly defect. Immunoprecipitation and mass spectrometry analyses identified mitochondrial ribosomal protein (MRP)L14 as the specific interacting protein partner of C7orf30 in the mt-LSU. Reciprocal experiments in which MRPL14 was depleted by small interfering RNA (siRNA) phenocopied the C7orf30 knockdown. Members of the DUF143 family have been suggested to be universally conserved ribosomal silencing factors, acting by sterically inhibiting the association of the small and large ribosomal subunits. Our results demonstrate that, although the interaction between C7orf30 and MRPL14 has been evolutionarily conserved, human C7orf30 is, on the contrary, essential for mitochondrial ribosome biogenesis and mitochondrial translation.

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 YBEY is an essential biogenesis factor for mitochondrial ribosomes

2020 ◽  
Vol 48 (17) ◽  
pp. 9762-9786 ◽  
Author(s):  
Sabrina Summer ◽  
Anna Smirnova ◽  
Alessandro Gabriele ◽  
Ursula Toth ◽  
Akinyemi Mandela Fasemore ◽  
...  
Keyword(s):  
16S Rrna ◽  
Ribosome Biogenesis ◽  
Specific Interaction ◽  
Ribosomal Subunit ◽  
Small Subunit ◽  
12S Rrna ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Abnormal Mitochondria

Abstract Ribosome 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 helps to properly incorporate uS11m into 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 The Yeast GTPase Mtg2p Is Required for Mitochondrial Translation and Partially Suppresses an rRNA Methyltransferase Mutant,mrm2

2005 ◽  
Vol 16 (2) ◽  
pp. 954-963 ◽  
Author(s):  
Kaustuv Datta ◽  
Jennifer L. Fuentes ◽  
Janine R. Maddock
Keyword(s):  
Mitochondrial Dna ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Mitochondrial Protein ◽  
Ribosomal Subunit ◽  
Temporal Association ◽  
Temperature Sensitive ◽  
Dependent Manner ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosome

The assembly of ribosomes involves the coordinated processing and modification of rRNAs with the temporal association of ribosomal proteins. This process is regulated by assembly factors such as helicases, modifying enzymes, and GTPases. In contrast to the assembly of cytoplasmic ribosomes, there is a paucity of information concerning the role of assembly proteins in the biogenesis of mitochondrial ribosomes. In this study, we demonstrate that the Saccharomyces cerevisiae GTPase Mtg2p (Yhr168wp) is essential for mitochondrial ribosome function. Cells lacking MTG2 lose their mitochondrial DNA, giving rise to petite cells. In addition, cells expressing a temperature-sensitive mgt2-1 allele are defective in mitochondrial protein synthesis and contain lowered levels of mitochondrial ribosomal subunits. Significantly, elevated levels of Mtg2p partially suppress the thermosensitive loss of mitochondrial DNA in a 21S rRNA methyltransferase mutant, mrm2. We propose that Mtg2p is involved in mitochondrial ribosome biogenesis. Consistent with this role, we show that Mtg2p is peripherally localized to the mitochondrial inner membrane and associates with the 54S large ribosomal subunit in a salt-dependent manner.

scholarly journals Structural basis of GTPase-mediated mitochondrial ribosome biogenesis and recycling

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Hauke S. Hillen ◽  
Elena Lavdovskaia ◽  
Franziska Nadler ◽  
Elisa Hanitsch ◽  
Andreas Linden ◽  
...  
Keyword(s):  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
Structural Basis ◽  
Peptidyl Transferase ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
In Vitro Reconstitution

AbstractRibosome biogenesis requires auxiliary factors to promote folding and assembly of ribosomal proteins and RNA. Particularly, maturation of the peptidyl transferase center (PTC) is mediated by conserved GTPases, but the molecular basis is poorly understood. Here, we define the mechanism of GTPase-driven maturation of the human mitochondrial large ribosomal subunit (mtLSU) using endogenous complex purification, in vitro reconstitution and cryo-EM. Structures of transient native mtLSU assembly intermediates that accumulate in GTPBP6-deficient cells reveal how the biogenesis factors GTPBP5, MTERF4 and NSUN4 facilitate PTC folding. Addition of recombinant GTPBP6 reconstitutes late mtLSU biogenesis in vitro and shows that GTPBP6 triggers a molecular switch and progression to a near-mature PTC state. Additionally, cryo-EM analysis of GTPBP6-treated mature mitochondrial ribosomes reveals the structural basis for the dual-role of GTPBP6 in ribosome biogenesis and recycling. Together, these results provide a framework for understanding step-wise PTC folding as a critical conserved quality control checkpoint.

scholarly journals Proteomic profiling of the mitochondrial ribosome identifies Atp25 as a composite mitochondrial precursor protein

2016 ◽  
Vol 27 (20) ◽  
pp. 3031-3039 ◽  
Author(s):  
Michael W. Woellhaf ◽  
Frederik Sommer ◽  
Michael Schroda ◽  
Johannes M. Herrmann
Keyword(s):  
Precursor Protein ◽  
Ribosomal Biogenesis ◽  
Proteomic Profiling ◽  
Mitochondrial Translation ◽  
Bacterial Ribosome ◽  
Mitochondrial Ribosome ◽  
Translation Apparatus ◽  
The Matrix ◽  
Processing Peptidase ◽  
And Function

Whereas the structure and function of cytosolic ribosomes are well characterized, we only have a limited understanding of the mitochondrial translation apparatus. Using SILAC-based proteomic profiling, we identified 13 proteins that cofractionated with the mitochondrial ribosome, most of which play a role in translation or ribosomal biogenesis. One of these proteins is a homologue of the bacterial ribosome-silencing factor (Rsf). This protein is generated from the composite precursor protein Atp25 upon internal cleavage by the matrix processing peptidase MPP, and in this respect, it differs from all other characterized mitochondrial proteins of baker’s yeast. We observed that cytosolic expression of Rsf, but not of noncleaved Atp25 protein, is toxic. Our results suggest that eukaryotic cells face the challenge of avoiding negative interference from the biogenesis of their two distinct translation machineries.

scholarly journals Human Cytomegalovirus Infection Upregulates the Mitochondrial Transcription and Translation Machineries

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
S. Karniely ◽  
M. P. Weekes ◽  
R. Antrobus ◽  
J. Rorbach ◽  
L. van Haute ◽  
...  
Keyword(s):  
Tumor Cells ◽  
Human Cytomegalovirus ◽  
Mitochondrial Biogenesis ◽  
Ribosome Biogenesis ◽  
Hcmv Infection ◽  
Aerobic Glycolysis ◽  
Tricarboxylic Acid Cycle ◽  
Mitochondrial Translation ◽  
Mitochondrial Transcription ◽  
Mitochondrial Ribosome

ABSTRACT Infection with human cytomegalovirus (HCMV) profoundly affects cellular metabolism. Like in tumor cells, HCMV infection increases glycolysis, and glucose carbon is shifted from the mitochondrial tricarboxylic acid cycle to the biosynthesis of fatty acids. However, unlike in many tumor cells, where aerobic glycolysis is accompanied by suppression of mitochondrial oxidative phosphorylation, HCMV induces mitochondrial biogenesis and respiration. Here, we affinity purified mitochondria and used quantitative mass spectrometry to determine how the mitochondrial proteome changes upon HCMV infection. We found that the mitochondrial transcription and translation systems are induced early during the viral replication cycle. Specifically, proteins involved in biogenesis of the mitochondrial ribosome were highly upregulated by HCMV infection. Inhibition of mitochondrial translation with chloramphenicol or knockdown of HCMV-induced ribosome biogenesis factor MRM3 abolished the HCMV-mediated increase in mitochondrially encoded proteins and significantly impaired viral growth under bioenergetically restricting conditions. Our findings demonstrate how HCMV manipulates mitochondrial biogenesis to support its replication. IMPORTANCE Human cytomegalovirus (HCMV), a betaherpesvirus, is a leading cause of morbidity and mortality during congenital infection and among immunosuppressed individuals. HCMV infection significantly changes cellular metabolism. Akin to tumor cells, in HCMV-infected cells, glycolysis is increased and glucose carbon is shifted from the tricarboxylic acid cycle to fatty acid biosynthesis. However, unlike in tumor cells, HCMV induces mitochondrial biogenesis even under aerobic glycolysis. Here, we have affinity purified mitochondria and used quantitative mass spectrometry to determine how the mitochondrial proteome changes upon HCMV infection. We find that the mitochondrial transcription and translation systems are induced early during the viral replication cycle. Specifically, proteins involved in biogenesis of the mitochondrial ribosome were highly upregulated by HCMV infection. Inhibition of mitochondrial translation with chloramphenicol or knockdown of HCMV-induced ribosome biogenesis factor MRM3 abolished the HCMV-mediated increase in mitochondrially encoded proteins and significantly impaired viral growth. Our findings demonstrate how HCMV manipulates mitochondrial biogenesis to support its replication.

scholarly journals MRM2 and MRM3 are involved in biogenesis of the large subunit of the mitochondrial ribosome

2014 ◽  
Vol 25 (17) ◽  
pp. 2542-2555 ◽  
Author(s):  
Joanna Rorbach ◽  
Pierre Boesch ◽  
Payam A. Gammage ◽  
Thomas J. J. Nicholls ◽  
Sarah F. Pearce ◽  
...  
Keyword(s):  
16S Rrna ◽  
Rna Processing ◽  
Large Subunit ◽  
Peptidyl Transferase ◽  
Mitochondrial Translation ◽  
Peptidyl Transferase Center ◽  
Mitochondrial Ribosome ◽  
Translation Apparatus ◽  
Rrna Maturation ◽  
And Function

Defects of the translation apparatus in human mitochondria are known to cause disease, yet details of how protein synthesis is regulated in this organelle remain to be unveiled. Ribosome production in all organisms studied thus far entails a complex, multistep pathway involving a number of auxiliary factors. This includes several RNA processing and modification steps required for correct rRNA maturation. Little is known about the maturation of human mitochondrial 16S rRNA and its role in biogenesis of the mitoribosome. Here we investigate two methyltransferases, MRM2 (also known as RRMJ2, encoded by FTSJ2) and MRM3 (also known as RMTL1, encoded by RNMTL1), that are responsible for modification of nucleotides of the 16S rRNA A-loop, an essential component of the peptidyl transferase center. Our studies show that inactivation of MRM2 or MRM3 in human cells by RNA interference results in respiratory incompetence as a consequence of diminished mitochondrial translation. Ineffective translation in MRM2- and MRM3-depleted cells results from aberrant assembly of the large subunit of the mitochondrial ribosome (mt-LSU). Our findings show that MRM2 and MRM3 are human mitochondrial methyltransferases involved in the modification of 16S rRNA and are important factors for the biogenesis and function of the large subunit of the mitochondrial ribosome.

scholarly journals YbeY is required for ribosome small subunit assembly and tRNA processing in human mitochondria

2019 ◽  
Author(s):  
Aaron R. D’Souza ◽  
Lindsey Van Haute ◽  
Christopher A. Powell ◽  
Pedro Rebelo-Guiomar ◽  
Joanna Rorbach ◽  
...  
Keyword(s):  
Small Subunit ◽  
Dual Function ◽  
Mitochondrial Translation ◽  
Trna Processing ◽  
Mitochondrial Ribosome ◽  
Severe Reduction ◽  
Translation Apparatus ◽  
Additional Protein ◽  
Processing Steps ◽  
Issue Section

AbstractMitochondria contain their own translation apparatus which enables them to produce the polypeptides encoded in their genome. The mitochondrially-encoded RNA components of the mitochondrial ribosome require various post-transcriptional processing steps. Additional protein factors are required to facilitate the biogenesis of the functional mitoribosome. We have characterised a mitochondrially-localized protein, YbeY, which interacts with the assembling mitoribosome through the small subunit. Loss of YbeY leads to a severe reduction in mitochondrial translation and a loss of cell viability, caused by less accurate mitochondrial mt-tRNASer(AGY) processing from the primary transcript and an accumulation of immature mitochondrial small subunit. Our results suggest that YbeY performs a dual function in mitochondria coupling tRNA processing to mitoribosome biogenesis.Issue SectionNucleic Acid EnzymesAbstract Figure

scholarly journals Chaperone-E3 Ligase Complex HSP70-CHIP Mediates Ubiquitination of Ribosomal Protein S3

2018 ◽  
Vol 19 (9) ◽  
pp. 2723 ◽  
Author(s):  
Inwoo Hwang ◽  
Sung-Woo Cho ◽  
Jee-Yin Ahn
Keyword(s):  
Ribosomal Protein ◽  
Ribosome Biogenesis ◽  
Ribosomal Subunit ◽  
E3 Ligase ◽  
Interacting Protein ◽  
Akt Activation ◽  
Protein Levels ◽  
40S Ribosomal Subunit ◽  
Subsequent Degradation ◽  
Ribosomal Protein S3

In addition to its role in ribosome biogenesis, ribosomal protein S3 (RPS3), a component of the 40S ribosomal subunit, has been suggested to possess several extraribosomal functions, including an apoptotic function. In this study, we demonstrated that in the mouse brain, the protein levels of RPS3 were altered by the degree of nutritional starvation and correlated with neuronal apoptosis. After endurable short-term starvation, the apoptotic function of RPS3 was suppressed by Akt activation and Akt-mediated T70 phosphorylation, whereas after prolonged starvation, the protein levels of RPS3 notably increased, and abundant neuronal death occurred. These events coincided with ubiquitination and subsequent degradation of RPS3, controlled by HSP70 and the cochaperone E3 ligase: carboxy terminus of heat shock protein 70-interacting protein (CHIP). Thus, our study points to an extraribosomal role of RPS3 in balancing neuronal survival or death depending on the degree of starvation through CHIP-mediated polyubiquitination and degradation.

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