scholarly journals Selective over-synthesis and rapid turnover of mitochondrial protein components of respiratory complexes

2019 ◽  
Author(s):  
Daniel F. Bogenhagen
Keyword(s):  
Nuclear Dna ◽  
Mitochondrial Protein ◽  
Cluster Assembly ◽  
Mitochondrial Ribosomes ◽  
Mammalian Mitochondria ◽  
The Matrix ◽  
Assembly Kinetics ◽  
Rieske Fes Protein ◽  
Protein Components ◽  
Cytoplasmic Ribosomes

AbstractMammalian mitochondria assemble four complexes of the respiratory chain (RCI, III, IV and V) by combining 13 polypeptides synthesized within mitochondria on mitochondrial ribosomes (mitoribosomes) with over 70 polypeptides encoded in nuclear DNA, translated on cytoplasmic ribosomes and imported into mitochondria. We report that pulse-chase SILAC can also serve as a valuable approach to study RC assembly as it reveals considerable differences in the rates and efficiency of assembly of different complexes. While assembly of RCV, ATPase, was rapid with little excess synthesis of subunits, RCI, NADH dehydrogenase, assembly was far less efficient with dramatic over-synthesis of numerous proteins, particularly in the matrix exposed N- and Q- Domains. Subunits that do not engage in assembly are generally degraded within three hours. Differential assembly kinetics were also observed for individual complexes immunoprecipitated with complex-specific antibodies. Immunoprecipitation with an antibody that recognizes the ND1 subunit of RCI co-precipitated a number of proteins implicated in FeS cluster assembly as well as newly-synthesized UQCRFS1, the Rieske FeS protein in RCIII, reflecting a degree of coordination of RCI and RCIII assembly.

scholarly journals Pulse-chase SILAC–based analyses reveal selective oversynthesis and rapid turnover of mitochondrial protein components of respiratory complexes

2020 ◽  
Vol 295 (9) ◽  
pp. 2544-2554 ◽  
Author(s):  
Daniel F. Bogenhagen ◽  
John D. Haley
Keyword(s):  
Nuclear Dna ◽  
Isotope Labeling ◽  
Mitochondrial Protein ◽  
Cluster Assembly ◽  
Mitochondrial Ribosomes ◽  
Mammalian Mitochondria ◽  
The Matrix ◽  
Assembly Kinetics ◽  
Rieske Fes Protein ◽  
Protein Components

Mammalian mitochondria assemble four complexes of the respiratory chain (RCI, RCIII, RCIV, and RCV) by combining 13 polypeptides synthesized within mitochondria on mitochondrial ribosomes (mitoribosomes) with over 70 polypeptides encoded in nuclear DNA, translated on cytoplasmic ribosomes, and imported into mitochondria. We have previously observed that mitoribosome assembly is inefficient because some mitoribosomal proteins are produced in excess, but whether this is the case for other mitochondrial assemblies such as the RCs is unclear. We report here that pulse-chase stable isotope labeling with amino acids in cell culture (SILAC) is a valuable technique to study RC assembly because it can reveal considerable differences in the assembly rates and efficiencies of the different complexes. The SILAC analyses of HeLa cells indicated that assembly of RCV, comprising F1/Fo-ATPase, is rapid with little excess subunit synthesis, but that assembly of RCI (i.e. NADH dehydrogenase) is far less efficient, with dramatic oversynthesis of numerous proteins, particularly in the matrix-exposed N and Q domains. Unassembled subunits were generally degraded within 3 h. We also observed differential assembly kinetics for individual complexes that were immunoprecipitated with complex-specific antibodies. Immunoprecipitation with an antibody that recognizes the ND1 subunit of RCI co-precipitated a number of proteins implicated in FeS cluster assembly and newly synthesized ubiquinol-cytochrome c reductase Rieske iron-sulfur polypeptide 1 (UQCRFS1), the Rieske FeS protein in RCIII, reflecting some coordination between RCI and RCIII assemblies. We propose that pulse-chase SILAC labeling is a useful tool for studying rates of protein complex assembly and degradation.

scholarly journals MRPS25 mutations impair mitochondrial translation and cause encephalomyopathy

2019 ◽  
Vol 28 (16) ◽  
pp. 2711-2719 ◽  
Author(s):  
Enrico Bugiardini ◽  
Alice L Mitchell ◽  
Ilaria Dalla Rosa ◽  
Hue-Tran Horning-Do ◽  
Alan M Pitmann ◽  
...  
Keyword(s):  
Respiratory Chain ◽  
Mitochondrial Protein ◽  
In Silico Analysis ◽  
Small Subunit ◽  
Mitochondrial Translation ◽  
Transgenic Expression ◽  
Mitochondrial Ribosomes ◽  
Mitochondrial Ribosome ◽  
Protein Components ◽  
Biochemical Analyses

Abstract Mitochondrial disorders are clinically and genetically heterogeneous and are associated with a variety of disease mechanisms. Defects of mitochondrial protein synthesis account for the largest subgroup of disorders manifesting with impaired respiratory chain capacity; yet, only a few have been linked to dysfunction in the protein components of the mitochondrial ribosomes. Here, we report a subject presenting with dyskinetic cerebral palsy and partial agenesis of the corpus callosum, while histochemical and biochemical analyses of skeletal muscle revealed signs of mitochondrial myopathy. Using exome sequencing, we identified a homozygous variant c.215C>T in MRPS25, which encodes for a structural component of the 28S small subunit of the mitochondrial ribosome (mS25). The variant segregated with the disease and substitutes a highly conserved proline residue with leucine (p.P72L) that, based on the high-resolution structure of the 28S ribosome, is predicted to compromise inter-protein contacts and destabilize the small subunit. Concordant with the in silico analysis, patient’s fibroblasts showed decreased levels of MRPS25 and other components of the 28S subunit. Moreover, assembled 28S subunits were scarce in the fibroblasts with mutant mS25 leading to impaired mitochondrial translation and decreased levels of multiple respiratory chain subunits. Crucially, these abnormalities were rescued by transgenic expression of wild-type MRPS25 in the mutant fibroblasts. Collectively, our data demonstrate the pathogenicity of the p.P72L variant and identify MRPS25 mutations as a new cause of mitochondrial translation defect.

scholarly journals Mitochondrial Chaperones and Proteases in Cardiomyocytes and Heart Failure

2021 ◽  
Vol 8 ◽  
Author(s):  
Zee Chen ◽  
Lei Huang ◽  
Alexandria Tso ◽  
Shijia Wang ◽  
Xi Fang ◽  
...  
Keyword(s):  
Heart Failure ◽  
Nuclear Dna ◽  
Mitochondrial Protein ◽  
Mitochondrial Proteins ◽  
Protein Homeostasis ◽  
Oxygen Species ◽  
Mitochondrial Quality Control ◽  
The Matrix ◽  
Intracellular Ca ◽  
Mitochondrial Chaperones

Heart failure is one of the leading causes of morbidity and mortality worldwide. In cardiomyocytes, mitochondria are not only essential organelles providing more than 90% of the ATP necessary for contraction, but they also play critical roles in regulating intracellular Ca2+ signaling, lipid metabolism, production of reactive oxygen species (ROS), and apoptosis. Because mitochondrial DNA only encodes 13 proteins, most mitochondrial proteins are nuclear DNA-encoded, synthesized, and transported from the cytoplasm, refolded in the matrix to function alone or as a part of a complex, and degraded if damaged or incorrectly folded. Mitochondria possess a set of endogenous chaperones and proteases to maintain mitochondrial protein homeostasis. Perturbation of mitochondrial protein homeostasis usually precedes disruption of the whole mitochondrial quality control system and is recognized as one of the hallmarks of cardiomyocyte dysfunction and death. In this review, we focus on mitochondrial chaperones and proteases and summarize recent advances in understanding how these proteins are involved in the initiation and progression of heart failure.

scholarly journals Biogenesis of mitochondria*. The effects of physiological and genetic manipulation of Saccharomyces cerevisiae on the mitochondrial transport systems for tricarboxylate-cycle anions

1973 ◽  
Vol 134 (4) ◽  
pp. 923-934 ◽  
Author(s):  
Margaret Perkins ◽  
J. M. Haslam ◽  
Anthony W. Linnane
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Genetic Manipulation ◽  
Mitochondrial Protein ◽  
Transport Systems ◽  
Mammalian Mitochondria ◽  
Biogenesis Of Mitochondria ◽  
Protein Components ◽  
Carrier Systems ◽  
Mammalian System ◽  
Tricarboxylate Cycle

1. Kinetic and equilibrium parameters for the uptake of l-malate, succinate, citrate and α-oxoglutarate by fully functional mitochondria of Saccharomyces cerevisiae were determined. 2. The uptake of l-malate and succinate is mediated by a common carrier, and two other distinct carriers mediate the uptake of citrate and α-oxoglutarate. 3. The properties of the carrier systems for l-malate, succinate and citrate closely resemble those of mammalian mitochondria, but the α-oxoglutarate carrier differs from the mammalian system in minor respects. 4. The composition of the yeast mitochondria was extensively manipulated by (a) anaerobiosis, (b) catabolite repression, (c) inhibition of mitochondrial protein synthesis and (d) elimination of mitochondrial DNA by mutation. 5. The carrier systems for l-malate, succinate, citrate and α-oxoglutarate are essentially similar in the five different types of mitochondria. 6. It is concluded that all the protein components of the carrier systems for l-malate, succinate, citrate and α-oxoglutarate are coded by nuclear genes and synthesized extramitochondrially by cell-sap ribosomes.

scholarly journals Characterization of Mmp37p, aSaccharomyces cerevisiaeMitochondrial Matrix Protein with a Role in Mitochondrial Protein Import

2006 ◽  
Vol 17 (9) ◽  
pp. 4051-4062 ◽  
Author(s):  
Michelle R. Gallas ◽  
Mary K. Dienhart ◽  
Rosemary A. Stuart ◽  
Roy M. Long
Keyword(s):  
Matrix Protein ◽  
Protein Import ◽  
Mitochondrial Protein ◽  
Temperature Sensitive ◽  
Inner Membrane ◽  
Mitochondrial Inner Membrane ◽  
Close Proximity ◽  
The Matrix ◽  
Targeting Signal

Many mitochondrial proteins are encoded by nuclear genes and after translation in the cytoplasm are imported via translocases in the outer and inner membranes, the TOM and TIM complexes, respectively. Here, we report the characterization of the mitochondrial protein, Mmp37p (YGR046w) and demonstrate its involvement in the process of protein import into mitochondria. Haploid cells deleted of MMP37 are viable but display a temperature-sensitive growth phenotype and are inviable in the absence of mitochondrial DNA. Mmp37p is located in the mitochondrial matrix where it is peripherally associated with the inner membrane. We show that Mmp37p has a role in the translocation of proteins across the mitochondrial inner membrane via the TIM23-PAM complex and further demonstrate that substrates containing a tightly folded domain in close proximity to their mitochondrial targeting sequences display a particular dependency on Mmp37p for mitochondrial import. Prior unfolding of the preprotein, or extension of the region between the targeting signal and the tightly folded domain, relieves their dependency for Mmp37p. Furthermore, evidence is presented to show that Mmp37 may affect the assembly state of the TIM23 complex. On the basis of these findings, we hypothesize that the presence of Mmp37p enhances the early stages of the TIM23 matrix import pathway to ensure engagement of incoming preproteins with the mtHsp70p/PAM complex, a step that is necessary to drive the unfolding and complete translocation of the preprotein into the matrix.

Unstable mitochondrial DNA in natural-death nuclear mutants of Neurospora crassa

1989 ◽  
Vol 9 (10) ◽  
pp. 4259-4264
Author(s):  
B L Seidel-Rogol ◽  
J King ◽  
H Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Recessive Mutation ◽  
Natural Death ◽  
Mitochondrial Ribosomes ◽  
Large Deletions ◽  
Group I ◽  
Mitochondrial Functions ◽  
Mitochondrial Chromosome

The natural-death mutant of Neurospora crassa has an accelerated senescence phenotype caused by a recessive mutation, nd, in a nuclear gene that is located in linkage group I. An examination of mitochondrial functions, however, revealed that the mutant has phenotypic and molecular defects similar to those commonly associated with maternally transmitted fungal senescence syndromes, including (i) deficiencies in cytochromes aa3 and b; (ii) a deficit in small subunits of mitochondrial ribosomes, and hence defective mitochondrial protein synthesis; and (iii) accumulation of gross rearrangements, including large deletions, in the mitochondrial chromosome of vegetatively propagated cells. These traits indicate that the nd+ allele codes for a function that is essential for stable maintenance of the mitochondrial chromosome, possibly a protein involved in replication, repair, or recombination.

scholarly journals Mutation in the Fe–S scaffold protein Isu bypasses frataxin deletion

2011 ◽  
Vol 441 (1) ◽  
pp. 473-480 ◽  
Author(s):  
Heeyong Yoon ◽  
Ramesh Golla ◽  
Emmanuel Lesuisse ◽  
Jayashree Pain ◽  
Jason E. Donald ◽  
...  
Keyword(s):  
Unique Feature ◽  
Mitochondrial Protein ◽  
Scaffold Protein ◽  
Yeast Cells ◽  
Single Amino Acid ◽  
Cluster Assembly ◽  
Iron Availability ◽  
Direct Effects ◽  
Cysteine Desulfurase ◽  
Mitochondrial Iron

Frataxin is a conserved mitochondrial protein deficient in patients with Friedreich's ataxia. Frataxin has been implicated in control of iron homoeostasis and Fe–S cluster assembly. In yeast or human mitochondria, frataxin interacts with components of the Fe–S cluster synthesis machinery, including the cysteine desulfurase Nfs1, accessory protein Isd11 and scaffold protein Isu. In the present paper, we report that a single amino acid substitution (methionine to isoleucine) at position 107 in the mature form of Isu1 restored many deficient functions in Δyfh1 or frataxin-depleted yeast cells. Iron homoeostasis was improved such that soluble/usable mitochondrial iron was increased and accumulation of insoluble/non-usable iron within mitochondria was largely prevented. Cytochromes were returned to normal and haem synthesis was restored. In mitochondria carrying the mutant Isu1 and no frataxin, Fe–S cluster enzyme activities were improved. The efficiency of new Fe–S cluster synthesis in isolated mitochondria was markedly increased compared with frataxin-negative cells, although the response to added iron was minimal. The M107I substitution in the highly conserved Isu scaffold protein is typically found in bacterial orthologues, suggesting that a unique feature of the bacterial Fe–S cluster machinery may be involved. The mechanism by which the mutant Isu bypasses the absence of frataxin remains to be determined, but could be related to direct effects on Fe–S cluster assembly and/or indirect effects on mitochondrial iron availability.

scholarly journals Unstable mitochondrial DNA in natural-death nuclear mutants of Neurospora crassa.

1989 ◽  
Vol 9 (10) ◽  
pp. 4259-4264 ◽  
Author(s):  
B L Seidel-Rogol ◽  
J King ◽  
H Bertrand
Keyword(s):  
Neurospora Crassa ◽  
Mitochondrial Protein ◽  
Nuclear Gene ◽  
Recessive Mutation ◽  
Natural Death ◽  
Mitochondrial Ribosomes ◽  
Large Deletions ◽  
Group I ◽  
Mitochondrial Functions ◽  
Mitochondrial Chromosome

The natural-death mutant of Neurospora crassa has an accelerated senescence phenotype caused by a recessive mutation, nd, in a nuclear gene that is located in linkage group I. An examination of mitochondrial functions, however, revealed that the mutant has phenotypic and molecular defects similar to those commonly associated with maternally transmitted fungal senescence syndromes, including (i) deficiencies in cytochromes aa3 and b; (ii) a deficit in small subunits of mitochondrial ribosomes, and hence defective mitochondrial protein synthesis; and (iii) accumulation of gross rearrangements, including large deletions, in the mitochondrial chromosome of vegetatively propagated cells. These traits indicate that the nd+ allele codes for a function that is essential for stable maintenance of the mitochondrial chromosome, possibly a protein involved in replication, repair, or recombination.

scholarly journals Mitochondrial Respiratory Chain Protein Co-Regulation in the Human Brain

2021 ◽  
Author(s):  
Caroline Trumpff ◽  
Edward Owusu-Ansah ◽  
Hans-Ulrich Klein ◽  
Annie Lee ◽  
Vladislav Petyuk ◽  
...  
Keyword(s):  
Human Brain ◽  
Respiratory Chain ◽  
Complex I ◽  
Molecular Mechanisms ◽  
Nuclear Dna ◽  
Mitochondrial Protein ◽  
Mitochondrial Respiratory Chain ◽  
Mtdna Copy Number ◽  
Mt Dna ◽  
Mitochondrial Respiratory

Mitochondrial respiratory chain (RC) function requires the stochiometric interaction among dozens of proteins but their co-regulation has not been defined in the human brain. Here, using quantitative proteomics across three independent cohorts we systematically characterized the co-regulation patterns of mitochondrial RC proteins in the human dorsolateral prefrontal cortex (DLPFC). Whereas the abundance of RC protein subunits that physically assemble into stable complexes were correlated, indicating their co-regulation, RC assembly factors exhibited modest co-regulation. Within complex I, nuclear DNA-encoded subunits exhibited >2.5-times higher co-regulation than mitochondrial (mt)DNA-encoded subunits. Moreover, mtDNA copy number was unrelated to mtDNA-encoded subunits abundance, suggesting that mtDNA content is not limiting. Alzheimer disease (AD) brains exhibited reduced abundance of complex I RC subunits, an effect largely driven by a 2-4% overall lower mitochondrial protein content. These findings provide foundational knowledge to identify molecular mechanisms contributing to age- and disease-related erosion of mitochondrial function in the human brain.

scholarly journals Identification of Novel Mitochondrial Protein Components ofChlamydomonas reinhardtii. A Proteomic Approach

2003 ◽  
Vol 132 (1) ◽  
pp. 318-330 ◽  
Author(s):  
Robert van Lis ◽  
Ariane Atteia ◽  
Guillermo Mendoza-Hernández ◽  
Diego González-Halphen
Keyword(s):  
Mitochondrial Protein ◽  
Proteomic Approach ◽  
Protein Components
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