scholarly journals Yeast nuclear PET127 gene can suppress deletions of the SUV3 or DSS1 genes: an indication of a functional interaction between 3' and 5' ends of mitochondrial mRNAs.

1998 ◽  
Vol 45 (4) ◽  
pp. 935-940 ◽  
Author(s):  
T Wegierski ◽  
A Dmochowska ◽  
A Jabłonowska ◽  
A Dziembowski ◽  
E Bartnik ◽  
...  
Keyword(s):  
Copy Number ◽  
Molecular Level ◽  
Nuclear Gene ◽  
Functional Coupling ◽  
Mitochondrial Rna ◽  
Gene Products ◽  
Mitochondrial Translation ◽  
Functional Interaction ◽  
Negative Phenotype

Saccharomyces cerevisiae nuclear genes SUV3 and DSS1 encode putative RNA helicase and RNase II, respectively, which are subunits of the mitochondrial degradosome (mtEXO): a three-protein complex which has a 3' to 5' exoribonuclease activity and plays a major role in regulating stability of mitochondrial RNA. Lack of either of the two gene products results in a respiratory negative phenotype, while on the molecular level it causes a total block of mitochondrial translation, loss of the in vitro exoribonuclease activity and changes in stability and processing of many mtRNAs. We have found that the yeast nuclear gene PET127 present on a low or high copy number vector can effectively suppress the effects of the SUV3 or DSS1 gene disruptions. Since the product of the PET127 gene is involved in processing of the 5' ends of mitochondrial mRNAs, we suggest that there is a functional coupling between the 5' and 3' ends of mitochondrial mRNAs.

scholarly journals Atp10p Assists Assembly of Atp6p into the F0Unit of the Yeast Mitochondrial ATPase

2004 ◽  
Vol 279 (19) ◽  
pp. 19775-19780 ◽  
Author(s):  
Alexander Tzagoloff ◽  
Antoni Barrientos ◽  
Walter Neupert ◽  
Johannes M. Herrmann
Keyword(s):  
Nuclear Gene ◽  
Mitochondrial Atpase ◽  
Gene Products ◽  
Wild Type ◽  
Mitochondrial Translation ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Inner Membrane ◽  
Atpase Subunits ◽  
Specific Factors

The F0F1-ATPase complex of yeast mitochondria contains three mitochondrial and at least 17 nuclear gene products. The coordinate assembly of mitochondrial and cytosolic translation products relies on chaperones and specific factors that stabilize the pools of some unassembled subunits. Atp10p was identified as a mitochondrial inner membrane component necessary for the biogenesis of the hydrophobic F0sector of the ATPase. Here we show that, following its synthesis on mitochondrial ribosomes, subunit 6 of the ATPase (Atp6p) can be cross-linked to Atp10p. This interaction is required for the integration of Atp6p into a partially assembled subcomplex of the ATPase. Pulse labeling and chase of mitochondrial translation productsin vivoindicate that Atp6p is less stable and more rapidly degraded in anatp10null mutant than in wild type. Based on these observations, we propose Atp10p to be an Atp6p-specific chaperone that facilitates the incorporation of Atp6p into an intermediate subcomplex of ATPase subunits.

scholarly journals A human pathology-related mutation prevents import of an aminoacyl-tRNA synthetase into mitochondria

2011 ◽  
Vol 433 (3) ◽  
pp. 441-446 ◽  
Author(s):  
Marie Messmer ◽  
Catherine Florentz ◽  
Hagen Schwenzer ◽  
Gert C. Scheper ◽  
Marjo S. van der Knaap ◽  
...  
Keyword(s):  
Nuclear Gene ◽  
Trna Synthetase ◽  
Aminoacyl Trna Synthetase ◽  
Mitochondrial Translation ◽  
Gene Coding ◽  
Human Pathology ◽  
Key Enzyme ◽  
Targeting Signal

Mutations in the nuclear gene coding for the mitochondrial aspartyl-tRNA synthetase, a key enzyme for mitochondrial translation, are correlated with leukoencephalopathy. A Ser45 to Gly45 mutation is located in the predicted targeting signal of the protein. We demonstrate in the present study, by in vivo and in vitro approaches, that this pathology-related mutation impairs the import process across mitochondrial membranes.

scholarly journals C6orf203 is an RNA-binding protein involved in mitochondrial protein synthesis

2019 ◽  
Vol 47 (17) ◽  
pp. 9386-9399 ◽  
Author(s):  
Shreekara Gopalakrishna ◽  
Sarah F Pearce ◽  
Adam M Dinan ◽  
Florian A Schober ◽  
Miriam Cipullo ◽  
...  
Keyword(s):  
Rna Binding ◽  
Rna Binding Proteins ◽  
Binding Protein ◽  
Large Subunit ◽  
Regulation Of Gene Expression ◽  
Mitochondrial Protein ◽  
Rna Binding Protein ◽  
Mitochondrial Rna ◽  
Mitochondrial Translation

Abstract In all biological systems, RNAs are associated with RNA-binding proteins (RBPs), forming complexes that control gene regulatory mechanisms, from RNA synthesis to decay. In mammalian mitochondria, post-transcriptional regulation of gene expression is conducted by mitochondrial RBPs (mt-RBPs) at various stages of mt-RNA metabolism, including polycistronic transcript production, its processing into individual transcripts, mt-RNA modifications, stability, translation and degradation. To date, only a handful of mt-RBPs have been characterized. Here, we describe a putative human mitochondrial protein, C6orf203, that contains an S4-like domain—an evolutionarily conserved RNA-binding domain previously identified in proteins involved in translation. Our data show C6orf203 to bind highly structured RNA in vitro and associate with the mitoribosomal large subunit in HEK293T cells. Knockout of C6orf203 leads to a decrease in mitochondrial translation and consequent OXPHOS deficiency, without affecting mitochondrial RNA levels. Although mitoribosome stability is not affected in C6orf203-depleted cells, mitoribosome profiling analysis revealed a global disruption of the association of mt-mRNAs with the mitoribosome, suggesting that C6orf203 may be required for the proper maturation and functioning of the mitoribosome. We therefore propose C6orf203 to be a novel RNA-binding protein involved in mitochondrial translation, expanding the repertoire of factors engaged in this process.

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 Mitochondrial gene expression in Saccharomyces cerevisiae. Proteolysis of nascent chains in isolated yeast mitochondria optimized for protein synthesis

1991 ◽  
Vol 274 (1) ◽  
pp. 199-205 ◽  
Author(s):  
C L Black-Schaefer ◽  
J D McCourt ◽  
R O Poyton ◽  
E E McKee
Keyword(s):  
Protein Synthesis ◽  
Mitochondrial Gene ◽  
Mitochondrial Protein ◽  
Gene Products ◽  
Yeast Mitochondria ◽  
Mitochondrial Translation ◽  
True Rate ◽  
Isolated Mitochondria ◽  
Enzyme Complexes

We demonstrate here that mitochondrial translation products synthesized by isolated yeast mitochondria are subject to rapid proteolysis. The loss of label from mitochondrial peptides synthesized in vitro comes from two distinct pools of peptides: one that is rapidly degraded (t1/2 of minutes) and one that is much more resistant to proteolysis (t1/2 of hours). As the length of the incubation period increases, the percentage of labelled peptides in the rapidly-turning-over pool decreases and cannot be detected after 60 min of incubation. This proteolysis is inhibited by chloramphenicol and is dependent on the presence of ATP. The loss of label during the chase occurs from fully completed translation products. The proteolysis observed here markedly affects measurements of rates of mitochondrial protein synthesis in isolated yeast mitochondria. In earlier work, in which proteolysis was not considered, mitochondrial translation was thought to stop after 20-30 min of incubation. In the present study, by taking proteolysis into account, we demonstrate that the rate of translation in isolated mitochondria is actually constant for nearly 60 min and then decreases to near zero by 80 min of incorporation. These findings have allowed us to devise a procedure for measuring the ‘true’ rate of translation in isolated mitochondria. In addition, they suggest that mitochondrial translation products which normally assemble with nuclear-encoded gene products into multimeric enzyme complexes are unstable without their nuclear-encoded counterparts.

scholarly journals Mitochondrial RNA Import in Leishmania tropica: Aptamers Homologous to Multiple tRNA Domains That Interact Cooperatively or Antagonistically at the Inner Membrane

2002 ◽  
Vol 22 (12) ◽  
pp. 4372-4382 ◽  
Author(s):  
Subhendra Nath Bhattacharyya ◽  
Saibal Chatterjee ◽  
Samit Adhya
Keyword(s):  
Mitochondrial Rna ◽  
Type I ◽  
Type Ii ◽  
Sequence Motifs ◽  
Inner Mitochondrial Membrane ◽  
Mitochondrial Translation ◽  
Inner Membrane ◽  
The Matrix ◽  
Import Receptors

ABSTRACT A large number of cytoplasmic tRNAs are imported into the kinetoplast-mitochondrion of Leishmania by a receptor-mediated process. To identify the sequences recognized by import receptors, mitochondria were incubated with a combinatorial RNA library. Repeated cycles of amplification of the imported sequences (SELEX) resulted in rapid selection of several import aptamers containing sequence motifs present in the anticodon arm, the D arm, the V-T region, and acceptor stem of known tRNAs, confirming or suggesting the presence of import signals in these domains. As predicted, truncated derivatives of tRNAIle(UAU) containing the D arm or the V-T region were imported in vitro. Four aptamers were studied in detail. All were imported in vitro as well as in transiently transfected cells, using the same pathway as tRNA, but their individual import efficiencies were different. Two types of aptamers were discernible: the A arm and D arm homologues (type I), which were efficiently transferred across the inner mitochondrial membrane, and the V-T homologues (type II), which were not. Remarkably, subnanomolar concentrations of type I RNAs stimulated the entry of type II RNAs into the matrix, whereas type II RNAs inhibited inner membrane transfer of type I RNAs. Moreover, tRNATyr(GUA) and tRNAIle(UAU) interacted with one another as type I and type II, respectively. Such cooperative and antagonistic interactions may allow the use of a limited number of receptors to recognize a large number of tRNAs of variable affinity and enable the maintenance of a properly balanced tRNA pool for mitochondrial translation.

scholarly journals DNA replication in chloroplasts

1993 ◽  
Vol 104 (1) ◽  
pp. 1-9 ◽  
Author(s):  
S. Heinhorst ◽  
G.C. Cannon
Keyword(s):  
Dna Replication ◽  
Chloroplast Dna ◽  
Molecular Basis ◽  
Copy Number ◽  
Molecular Level ◽  
Gene Products ◽  
Biochemical Mechanism ◽  
Dna Molecule ◽  
Multiple Copies ◽  
Present Understanding

Chloroplasts contain multiple copies of a DNA molecule (the plastome) that encodes many of the gene products required to perform photosynthesis. The plastome is replicated by nuclear-encoded proteins and its copy number seems to be highly regulated by the cell in a tissue-specific and developmental manner. Our understanding of the biochemical mechanism by which the plastome is replicated and the molecular basis for its regulation is limited. In this commentary we review our present understanding of chloroplast DNA replication and examine current efforts to elucidate its mechanism at a molecular level.

In vitro transcription and translation of simian rotavirus SA11 gene products.

1980 ◽  
Vol 33 (3) ◽  
pp. 1111-1121 ◽  
Author(s):  
B B Mason ◽  
D Y Graham ◽  
M K Estes
Keyword(s):  
In Vitro Transcription ◽  
Gene Products

scholarly journals Adipo-Derived Stem Cell Features and MCF-7

Cells ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1754
Author(s):  
Giuseppe Garroni ◽  
Francesca Balzano ◽  
Sara Cruciani ◽  
Renzo Pala ◽  
Donatella Coradduzza ◽  
...  
Keyword(s):  
Stem Cell ◽  
Molecular Level ◽  
Cancer Cell Line ◽  
Human Adipose Tissue ◽  
Cell Cycle Regulators ◽  
Culturing Conditions ◽  
And Migration ◽  
Related Proteins ◽  
Mcf 7

Human adipose tissue-derived stem cells (hADSCs) are highly suitable for regeneration therapies being easily collected and propagated in vitro. The effects of different external factors and culturing conditions are able to affect hADSC proliferation, senescence, differentiation, and migration, even at the molecular level. In the present paper, we exposed hADSCs to an exhausted medium from the breast cancer cell line (MCF-7) to evaluate whether the soluble factors released by these cells may be able to induce changes in stem cell behavior. In particular, we investigated the expression of stemness-related genes (OCT4; Sox 2; Nanog), the cell-cycle regulators p21 (WAF1/CIP1) p53, epigenetic markers (DNMT1 and Sirt1), and autophagy-related proteins. From our results, we can infer that the exhausted medium from MCF-7 is able to influence the hADSCs behavior increasing the expression of stemness-related genes, cell proliferation, and autophagy. Polyamines detectable in MCF-7 exhausted medium could be related to the higher proliferation capability observed in hADSCs, suggesting direct crosstalk between these molecules and the observed changes in stem cell potency.

scholarly journals Mutations in nuclear gene cyt-4 of Neurospora crassa result in pleiotropic defects in processing and splicing of mitochondrial RNAs.

Genetics ◽  
1989 ◽  
Vol 123 (1) ◽  
pp. 97-108 ◽  
Author(s):  
K F Dobinson ◽  
M Henderson ◽  
R L Kelley ◽  
R A Collins ◽  
A M Lambowitz
Keyword(s):  
Neurospora Crassa ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Northern Hybridization ◽  
Rrna Gene ◽  
Mitochondrial Rna ◽  
Group I Introns ◽  
Group I ◽  
Processing Pathways ◽  
Aberrant Rna

Abstract The nuclear cyt-4 mutants of Neurospora crassa have been shown previously to be defective in splicing the group I intron in the mitochondrial large rRNA gene and in 3' end synthesis of the mitochondrial large rRNA. Here, Northern hybridization experiments show that the cyt-4-1 mutant has alterations in a number of mitochondrial RNA processing pathways, including those for cob, coI, coII and ATPase 6 mRNAs, as well as mitochondrial tRNAs. Defects in these pathways include inhibition of 5' and 3' end processing, accumulation of aberrant RNA species, and inhibition of splicing of both group I introns in the cob gene. The various defects in mitochondrial RNA synthesis in the cyt-4-1 mutant cannot be accounted for by deficiency of mitochondrial protein synthesis or energy metabolism, and they suggest that the cyt-4-1 mutant is defective in a component or components required for processing and/or turnover of a number of different mitochondrial RNAs. Defective splicing of the mitochondrial large rRNA intron in the cyt-4-1 mutant may be a secondary effect of failure to synthesize pre-rRNAs having the correct 3' end. However, a similar explanation cannot be invoked to account for defective splicing of the cob pre-mRNA introns, and the cyt-4-1 mutation may directly affect splicing of these introns.

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