Import of ribosomal proteins into yeast mitochondria

2014 ◽  
Vol 92 (6) ◽  
pp. 489-498 ◽  
Author(s):  
Michael W. Woellhaf ◽  
Katja G. Hansen ◽  
Christoph Garth ◽  
Johannes M. Herrmann
Keyword(s):  
Ribosomal Proteins ◽  
Current Knowledge ◽  
Matrix Proteins ◽  
Protein Subunits ◽  
Mitochondrial Ribosomes ◽  
Amphipathic Helices ◽  
Mitochondrial Ribosome ◽  
The Matrix ◽  
Positively Charged ◽  
Mitochondrial Targeting Sequences

Mitochondrial ribosomes of baker’s yeast contain at least 78 protein subunits. All but one of these proteins are nuclear-encoded, synthesized on cytosolic ribosomes, and imported into the matrix for biogenesis. The import of matrix proteins typically relies on N-terminal mitochondrial targeting sequences that form positively charged amphipathic helices. Interestingly, the N-terminal regions of many ribosomal proteins do not closely match the characteristics of matrix targeting sequences, suggesting that the import processes of these proteins might deviate to some extent from the general import route. So far, the biogenesis of only two ribosomal proteins, Mrpl32 and Mrp10, was studied experimentally and indeed showed surprising differences to the import of other preproteins. In this review article we summarize the current knowledge on the transport of proteins into the mitochondrial matrix, and thereby specifically focus on proteins of the mitochondrial ribosome.

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 Structural basis of GTPase-mediated mitochondrial ribosome biogenesis and recycling

2021 ◽  
Author(s):  
Hauke S. Hillen ◽  
Elena Lavdovskaia ◽  
Franziska Nadler ◽  
Elisa Hanitsch ◽  
Andreas Linden ◽  
...  
Keyword(s):  
Molecular Basis ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Large Subunit ◽  
Structural Basis ◽  
Catalytic Core ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Translation Systems

Ribosome biogenesis is an essential process that requires auxiliary factors to promote folding and assembly of ribosomal proteins and RNA. In particular, maturation of the peptidyl transferase center (PTC), the catalytic core of the ribosome, is mediated by universally conserved GTPases, but the molecular basis is poorly understood. Here, we define the mechanism of GTPase-driven maturation of the human mitochondrial ribosomal large subunit (mtLSU) using a combination of endogenous complex purification, in vitro reconstitution and cryo-electron microscopy (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. Subsequent addition of recombinant GTPBP6 reconstitutes late mtLSU biogenesis in vitro and shows that GTPBP6 triggers a molecular switch by releasing MTERF4-NSUN4 and GTPBP5 accompanied by the progression to a near-mature PTC state. In addition, 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 define the molecular basis of dynamic GTPase-mediated PTC maturation during mitochondrial ribosome biogenesis and provide a framework for understanding step-wise progression of PTC folding as a critical quality control checkpoint in all translation systems.

scholarly journals Abnormal Expression of Mitochondrial Ribosomal Proteins and Their Encoding Genes with Cell Apoptosis and Diseases

2020 ◽  
Vol 21 (22) ◽  
pp. 8879
Author(s):  
Guomin Huang ◽  
Hongyan Li ◽  
Hong Zhang
Keyword(s):  
Cell Apoptosis ◽  
Ribosomal Proteins ◽  
Mitochondrial Respiratory Chain ◽  
Basic Structure ◽  
Disease Diagnosis ◽  
Mitochondrial Ribosomes ◽  
Abnormal Expression ◽  
Metabolism Disorder ◽  
Mitochondrial Ribosome ◽  
Inducing Factors

Mammalian mitochondrial ribosomes translate 13 proteins encoded by mitochondrial genes, all of which play roles in the mitochondrial respiratory chain. After a long period of reconstruction, mitochondrial ribosomes are the most protein-rich ribosomes. Mitochondrial ribosomal proteins (MRPs) are encoded by nuclear genes, synthesized in the cytoplasm and then, transported to the mitochondria to be assembled into mitochondrial ribosomes. MRPs not only play a role in mitochondrial oxidative phosphorylation (OXPHOS). Moreover, they participate in the regulation of cell state as apoptosis inducing factors. Abnormal expressions of MRPs will lead to mitochondrial metabolism disorder, cell dysfunction, etc. Many researches have demonstrated the abnormal expression of MRPs in various tumors. This paper reviews the basic structure of mitochondrial ribosome, focuses on the structure and function of MRPs, and their relationships with cell apoptosis and diseases. It provides a reference for the study of the function of MRPs and the disease diagnosis and treatment.

scholarly journals The yeast protein Mam33 functions in the assembly of the mitochondrial ribosome

2019 ◽  
Vol 294 (25) ◽  
pp. 9813-9829 ◽  
Author(s):  
Gabrielle A. Hillman ◽  
Michael F. Henry
Keyword(s):  
Ribosomal Proteins ◽  
Matrix Protein ◽  
Synthetic Lethality ◽  
Large Subunit ◽  
Binding Assays ◽  
Safe Delivery ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Evolutionarily Conserved

Mitochondrial ribosomes are functionally specialized for the synthesis of several essential inner membrane proteins of the respiratory chain. Although remarkable progress has been made toward understanding the structure of mitoribosomes, the pathways and factors that facilitate their biogenesis remain largely unknown. The long unstructured domains of unassembled ribosomal proteins are highly prone to misfolding and often require dedicated chaperones to prevent aggregation. To date, chaperones that ensure safe delivery to the assembling ribosome have not been identified in the mitochondrion. In this study, a respiratory synthetic lethality screen revealed a role for an evolutionarily conserved mitochondrial matrix protein called Mam33 in Saccharomyces cerevisiae mitoribosome biogenesis. We found that the absence of Mam33 results in misassembled, aggregated ribosomes and a respiratory lethal phenotype in combination with other ribosome-assembly mutants. Using sucrose gradient sedimentation, native affinity purifications, in vitro binding assays, and SILAC-based quantitative proteomics, we found that Mam33 does not associate with the mature mitoribosome, but directly binds a subset of unassembled large subunit proteins. Based on these data, we propose that Mam33 binds specific mitoribosomal proteins to ensure proper assembly.

scholarly journals Ribosome Biogenesis and Cancer: Overview on Ribosomal Proteins

2021 ◽  
Vol 22 (11) ◽  
pp. 5496
Author(s):  
Annalisa Pecoraro ◽  
Martina Pagano ◽  
Giulia Russo ◽  
Annapina Russo
Keyword(s):  
Ribosomal Rna ◽  
Ribosomal Proteins ◽  
Ribosome Biogenesis ◽  
Protein Biosynthesis ◽  
Cellular Respiration ◽  
Mitochondrial Ribosomes ◽  
Ribonucleoprotein Complexes ◽  
Mitochondrial Ribosome ◽  
Energy Consuming ◽  
Cell Growth And Proliferation

Cytosolic ribosomes (cytoribosomes) are macromolecular ribonucleoprotein complexes that are assembled from ribosomal RNA and ribosomal proteins, which are essential for protein biosynthesis. Mitochondrial ribosomes (mitoribosomes) perform translation of the proteins essential for the oxidative phosphorylation system. The biogenesis of cytoribosomes and mitoribosomes includes ribosomal RNA processing, modification and binding to ribosomal proteins and is assisted by numerous biogenesis factors. This is a major energy-consuming process in the cell and, therefore, is highly coordinated and sensitive to several cellular stressors. In mitochondria, the regulation of mitoribosome biogenesis is essential for cellular respiration, a process linked to cell growth and proliferation. This review briefly overviews the key stages of cytosolic and mitochondrial ribosome biogenesis; summarizes the main steps of ribosome biogenesis alterations occurring during tumorigenesis, highlighting the changes in the expression level of cytosolic ribosomal proteins (CRPs) and mitochondrial ribosomal proteins (MRPs) in different types of tumors; focuses on the currently available information regarding the extra-ribosomal functions of CRPs and MRPs correlated to cancer; and discusses the role of CRPs and MRPs as biomarkers and/or molecular targets in cancer treatment.

scholarly journals Cryo-EM structure of the RNA-rich plant mitochondrial ribosome

2019 ◽  
Author(s):  
Florent Waltz ◽  
Heddy Soufari ◽  
Anthony Bochler ◽  
Philippe Giegé ◽  
Yaser Hashem
Keyword(s):  
Ribosomal Proteins ◽  
Microscopy Study ◽  
Electron Microscopy Study ◽  
Pentatricopeptide Repeat ◽  
Structural Investigations ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Eukaryotic Species ◽  
Specific Proteins ◽  
Pentatricopeptide Repeat Proteins

The vast majority of eukaryotic cells contain mitochondria, essential powerhouses and metabolic hubs1. These organelles have a bacterial origin and were acquired during an early endosymbiosis event2. Mitochondria possess specialized gene expression systems composed of various molecular machines including the mitochondrial ribosomes (mitoribosomes). Mitoribosomes are in charge of translating the few essential mRNAs still encoded by mitochondrial genomes3. While chloroplast ribosomes strongly resemble those of bacteria4,5, mitoribosomes have diverged significantly during evolution and present strikingly different structures across eukaryotic species6–10. In contrast to animals and trypanosomatides, plants mitoribosomes have unusually expanded ribosomal RNAs and conserved the short 5S rRNA, which is usually missing in mitoribosomes11. We have previously characterized the composition of the plant mitoribosome6revealing a dozen plant-specific proteins, in addition to the common conserved mitoribosomal proteins. In spite of the tremendous recent advances in the field, plant mitoribosomes remained elusive to high-resolution structural investigations, and the plant-specific ribosomal features of unknown structures. Here, we present a cryo-electron microscopy study of the plant 78S mitoribosome from cauliflower at near-atomic resolution. We show that most of the plant-specific ribosomal proteins are pentatricopeptide repeat proteins (PPR) that deeply interact with the plant-specific rRNA expansion segments. These additional rRNA segments and proteins reshape the overall structure of the plant mitochondrial ribosome, and we discuss their involvement in the membrane association and mRNA recruitment prior to translation initiation. Finally, our structure unveils an rRNA-constructive phase of mitoribosome evolution across eukaryotes.

Distribution of VLA-5 and VLA-4 fibronectin receptors in human monocytes demonstrated by immunofluorescence, immunocytochemistry, and autoradiography

1993 ◽  
Vol 51 ◽  
pp. 306-307
Author(s):  
Robert Williams ◽  
Che-Hung Lee ◽  
Sara E. Quella ◽  
David M. Harlan ◽  
Yuan-Hsu Kang
Keyword(s):  
Present Report ◽  
Matrix Proteins ◽  
Extracellular Matrices ◽  
Human Monocytes ◽  
Integrin Receptors ◽  
Morphological Evaluation ◽  
The Matrix ◽  
Specific Receptors ◽  
Cytokine Stimulation ◽  
Monocyte Adherence

Monocyte adherence to endothelial or extracellular matrices plays an important role in triggering monocyte activation in extravascular sites of infection, chronic inflammatory disorders, and tissue damage. Migration of monocytes in the tissues involves the response to a chemoattractant and movement by a series of attachments and detachments to the extracellular matrices which are regulated by expression and distribution of specific receptors for the matrix proteins such as fibronectin (FN). The VSAs (very late antigens or beta integrins), a subfamily of the transmembrane heterodimeric integrin receptors, have been thought to play a major role in monocyte adherence to the extracellular matrices and cells. In this subfamily, VLA-5 and VLA-4 are believed to be the most essential integrins mediating monocyte adherence to FN. In the present report, we have established and compared different procedures for morphological evaluation of the expression and distribution of the FN receptors on human monocytes in order to investigate their response to endotoxin or cytokine stimulation.

scholarly journals Functional relationship between the matrix proteins of feline and simian immunodeficiency viruses

Virology ◽  
2004 ◽  
Vol 329 (1) ◽  
pp. 157-167 ◽  
Author(s):  
Mariana L. Manrique ◽  
Silvia A. González ◽  
José L. Affranchino
Keyword(s):  
Functional Relationship ◽  
Matrix Proteins ◽  
The Matrix

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.

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