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1.
Nature ; 606(7913): 382-388, 2022 06.
Article in English | MEDLINE | ID: mdl-35614220

ABSTRACT

Mitochondria are epicentres of eukaryotic metabolism and bioenergetics. Pioneering efforts in recent decades have established the core protein componentry of these organelles1 and have linked their dysfunction to more than 150 distinct disorders2,3. Still, hundreds of mitochondrial proteins lack clear functions4, and the underlying genetic basis for approximately 40% of mitochondrial disorders remains unresolved5. Here, to establish a more complete functional compendium of human mitochondrial proteins, we profiled more than 200 CRISPR-mediated HAP1 cell knockout lines using mass spectrometry-based multiomics analyses. This effort generated approximately 8.3 million distinct biomolecule measurements, providing a deep survey of the cellular responses to mitochondrial perturbations and laying a foundation for mechanistic investigations into protein function. Guided by these data, we discovered that PIGY upstream open reading frame (PYURF) is an S-adenosylmethionine-dependent methyltransferase chaperone that supports both complex I assembly and coenzyme Q biosynthesis and is disrupted in a previously unresolved multisystemic mitochondrial disorder. We further linked the putative zinc transporter SLC30A9 to mitochondrial ribosomes and OxPhos integrity and established RAB5IF as the second gene harbouring pathogenic variants that cause cerebrofaciothoracic dysplasia. Our data, which can be explored through the interactive online MITOMICS.app resource, suggest biological roles for many other orphan mitochondrial proteins that still lack robust functional characterization and define a rich cell signature of mitochondrial dysfunction that can support the genetic diagnosis of mitochondrial diseases.


Subject(s)
Mitochondria , Mitochondrial Proteins , Cation Transport Proteins , Cell Cycle Proteins , Energy Metabolism , Humans , Mass Spectrometry , Mitochondria/genetics , Mitochondria/metabolism , Mitochondrial Diseases/genetics , Mitochondrial Diseases/metabolism , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Transcription Factors , rab5 GTP-Binding Proteins
2.
Elife ; 102021 08 02.
Article in English | MEDLINE | ID: mdl-34338637

ABSTRACT

Copy number variation through gene or chromosome amplification provides a route for rapid phenotypic variation and supports the long-term evolution of gene functions. Although the evolutionary importance of copy-number variation is known, little is understood about how genetic background influences its tolerance. Here, we measured fitness costs of over 4000 overexpressed genes in 15 Saccharomyces cerevisiae strains representing different lineages, to explore natural variation in tolerating gene overexpression (OE). Strain-specific effects dominated the fitness costs of gene OE. We report global differences in the consequences of gene OE, independent of the amplified gene, as well as gene-specific effects that were dependent on the genetic background. Natural variation in the response to gene OE could be explained by several models, including strain-specific physiological differences, resource limitations, and regulatory sensitivities. This work provides new insight on how genetic background influences tolerance to gene amplification and the evolutionary trajectories accessible to different backgrounds.


Subject(s)
DNA Copy Number Variations , Evolution, Molecular , Gene Expression , Genetic Fitness , Genetic Variation , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae/genetics , Genetic Background , Genome, Fungal , Genomics , Phenotype
3.
Nat Commun ; 12(1): 4769, 2021 08 06.
Article in English | MEDLINE | ID: mdl-34362905

ABSTRACT

Beyond its role in mitochondrial bioenergetics, Coenzyme Q (CoQ, ubiquinone) serves as a key membrane-embedded antioxidant throughout the cell. However, how CoQ is mobilized from its site of synthesis on the inner mitochondrial membrane to other sites of action remains a longstanding mystery. Here, using a combination of Saccharomyces cerevisiae genetics, biochemical fractionation, and lipid profiling, we identify two highly conserved but poorly characterized mitochondrial proteins, Ypl109c (Cqd1) and Ylr253w (Cqd2), that reciprocally affect this process. Loss of Cqd1 skews cellular CoQ distribution away from mitochondria, resulting in markedly enhanced resistance to oxidative stress caused by exogenous polyunsaturated fatty acids, whereas loss of Cqd2 promotes the opposite effects. The activities of both proteins rely on their atypical kinase/ATPase domains, which they share with Coq8-an essential auxiliary protein for CoQ biosynthesis. Overall, our results reveal protein machinery central to CoQ trafficking in yeast and lend insights into the broader interplay between mitochondria and the rest of the cell.


Subject(s)
Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , Ubiquinone/analogs & derivatives , Ubiquinone/metabolism , Antioxidants/metabolism , Lipids , Mitochondria/metabolism , Mitochondrial Membranes/metabolism , Mitochondrial Proteins/metabolism , Oxidative Stress , Phosphotransferases/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics
4.
J Biol Chem ; 296: 100643, 2021.
Article in English | MEDLINE | ID: mdl-33862086

ABSTRACT

Coenzyme Q (CoQ), a redox-active lipid essential for oxidative phosphorylation, is synthesized by virtually all cells, but how eukaryotes make the universal CoQ head group precursor 4-hydroxybenzoate (4-HB) from tyrosine is unknown. The first and last steps of this pathway have been defined in Saccharomyces cerevisiae, but the intermediates and enzymes involved in converting 4-hydroxyphenylpyruvate (4-HPP) to 4-hydroxybenzaldehyde (4-HBz) have not been described. Here, we interrogate this pathway with genetic screens, targeted LC-MS, and chemical genetics. We identify three redundant aminotransferases (Bna3, Bat2, and Aat2) that support CoQ biosynthesis in the absence of the established pathway tyrosine aminotransferases, Aro8 and Aro9. We use isotope labeling to identify bona fide tyrosine catabolites, including 4-hydroxyphenylacetate (4-HPA) and 4-hydroxyphenyllactate (4-HPL). Additionally, we find multiple compounds that rescue this pathway when exogenously supplemented, most notably 4-hydroxyphenylacetaldehyde (4-HPAA) and 4-hydroxymandelate (4-HMA). Finally, we show that the Ehrlich pathway decarboxylase Aro10 is dispensable for 4-HB production. These results define new features of 4-HB synthesis in yeast, demonstrate the redundant nature of this pathway, and provide a foundation for further study.


Subject(s)
Parabens/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , Transaminases/metabolism , Tyrosine/metabolism , Ubiquinone/analogs & derivatives , Oxidation-Reduction , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae Proteins/genetics , Transaminases/genetics , Ubiquinone/metabolism
5.
Anal Chem ; 93(9): 4217-4222, 2021 03 09.
Article in English | MEDLINE | ID: mdl-33617230

ABSTRACT

Mass spectrometry (MS) serves as the centerpiece technology for proteome, lipidome, and metabolome analysis. To gain a better understanding of the multifaceted networks of myriad regulatory layers in complex organisms, integration of different multiomic layers is increasingly performed, including joint extraction methods of diverse biomolecular classes and comprehensive data analyses of different omics. Despite the versatility of MS systems, fractured methodology drives nearly all MS laboratories to specialize in analysis of a single ome at the exclusion of the others. Although liquid chromatography-mass spectrometry (LC-MS) analysis is similar for different biomolecular classes, the integration on the instrument level is lagging behind. The recent advancements in high flow proteomics enable us to take a first step towards integration of protein and lipid analysis. Here, we describe a technology to achieve broad and deep coverage of multiple molecular classes simultaneously through multi-omic single-shot technology (MOST), requiring only one column, one LC-MS instrument, and a simplified workflow. MOST achieved great robustness and reproducibility. Its application to a Saccharomyces cerevisiae study consisting of 20 conditions revealed 2842 protein groups and 325 lipids and potential molecular relationships.


Subject(s)
Lipidomics , Proteome , Chromatography, Liquid , Reproducibility of Results , Technology
6.
J Cell Biol ; 218(4): 1353-1369, 2019 04 01.
Article in English | MEDLINE | ID: mdl-30674579

ABSTRACT

Coenzyme Q (CoQ) lipids are ancient electron carriers that, in eukaryotes, function in the mitochondrial respiratory chain. In mitochondria, CoQ lipids are built by an inner membrane-associated, multicomponent, biosynthetic pathway via successive steps of isoprenyl tail polymerization, 4-hydroxybenzoate head-to-tail attachment, and head modification, resulting in the production of CoQ. In yeast, we discovered that head-modifying CoQ pathway components selectively colocalize to multiple resolvable domains in vivo, representing supramolecular assemblies. In cells engineered with conditional ON or OFF CoQ pathways, domains were strictly correlated with CoQ production and substrate flux, respectively, indicating that CoQ lipid intermediates are required for domain formation. Mitochondrial CoQ domains were also observed in human cells, underscoring their conserved functional importance. CoQ domains within cells were highly enriched adjacent to ER-mitochondria contact sites. Together, our data suggest that CoQ domains function to facilitate substrate accessibility for processive and efficient CoQ production and distribution in cells.


Subject(s)
Endoplasmic Reticulum/enzymology , Enzymes/metabolism , Mitochondria/enzymology , Mitochondrial Proteins/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/enzymology , Ubiquinone/biosynthesis , Cell Line, Tumor , Endoplasmic Reticulum/genetics , Enzymes/genetics , Humans , Mitochondria/genetics , Mitochondrial Proteins/genetics , Multienzyme Complexes , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics , Substrate Specificity , Ubiquinone/genetics , Ubiquinone/metabolism
7.
Mol Cell ; 73(4): 763-774.e10, 2019 02 21.
Article in English | MEDLINE | ID: mdl-30661980

ABSTRACT

The biosynthesis of coenzyme Q presents a paradigm for how cells surmount hydrophobic barriers in lipid biology. In eukaryotes, CoQ precursors-among nature's most hydrophobic molecules-must somehow be presented to a series of enzymes peripherally associated with the mitochondrial inner membrane. Here, we reveal that this process relies on custom lipid-binding properties of COQ9. We show that COQ9 repurposes the bacterial TetR fold to bind aromatic isoprenes with high specificity, including CoQ intermediates that likely reside entirely within the bilayer. We reveal a process by which COQ9 associates with cardiolipin-rich membranes and warps the membrane surface to access this cargo. Finally, we identify a molecular interface between COQ9 and the hydroxylase COQ7, motivating a model whereby COQ9 presents intermediates directly to CoQ enzymes. Overall, our results provide a mechanism for how a lipid-binding protein might access, select, and deliver specific cargo from a membrane to promote biosynthesis.


Subject(s)
Membrane Lipids/metabolism , Mitochondrial Membranes/enzymology , Mitochondrial Proteins/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/enzymology , Ubiquinone/biosynthesis , Binding Sites , Cardiolipins/metabolism , Crystallography , Mitochondrial Proteins/chemistry , Mitochondrial Proteins/genetics , Molecular Docking Simulation , Molecular Dynamics Simulation , Protein Binding , Protein Conformation, alpha-Helical , Protein Transport , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/chemistry , Saccharomyces cerevisiae Proteins/genetics , Structure-Activity Relationship , Tryptophan , Ubiquinone/chemistry , Ubiquinone/genetics
8.
J Proteome Res ; 17(10): 3526-3536, 2018 10 05.
Article in English | MEDLINE | ID: mdl-30180576

ABSTRACT

The development of effective strategies for the comprehensive identification and quantification of proteoforms in complex systems is a critical challenge in proteomics. Proteoforms, the specific molecular forms in which proteins are present in biological systems, are the key effectors of biological function. Thus, knowledge of proteoform identities and abundances is essential to unraveling the mechanisms that underlie protein function. We recently reported a strategy that integrates conventional top-down mass spectrometry with intact-mass determinations for enhanced proteoform identifications and the elucidation of proteoform families and applied it to the analysis of yeast cell lysate. In the present work, we extend this strategy to enable quantification of proteoforms, and we examine changes in the abundance of murine mitochondrial proteoforms upon differentiation of mouse myoblasts to myotubes. The integrated top-down and intact-mass strategy provided an increase of ∼37% in the number of identified proteoforms compared to top-down alone, which is in agreement with our previous work in yeast; 1779 unique proteoforms were identified using the integrated strategy compared to 1301 using top-down analysis alone. Quantitative comparison of proteoform differences between the myoblast and myotube cell types showed 129 observed proteoforms exhibiting statistically significant abundance changes (fold change >2 and false discovery rate <5%).


Subject(s)
Mitochondria/metabolism , Mitochondrial Proteins/metabolism , Proteome/metabolism , Proteomics/methods , Tandem Mass Spectrometry/methods , Animals , Cell Differentiation , Cell Line , Mice , Muscle Fibers, Skeletal/cytology , Muscle Fibers, Skeletal/metabolism , Myoblasts/cytology , Myoblasts/metabolism , Reproducibility of Results , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/metabolism
9.
Cell Syst ; 6(6): 709-721.e6, 2018 06 27.
Article in English | MEDLINE | ID: mdl-29909275

ABSTRACT

The genetic regulation and physiological impact of most lipid species are unexplored. Here, we profiled 129 plasma lipid species across 49 strains of the BXD mouse genetic reference population fed either chow or a high-fat diet. By integrating these data with genomics and phenomics datasets, we elucidated genes by environment (diet) interactions that regulate systemic metabolism. We found quantitative trait loci (QTLs) for ∼94% of the lipids measured. Several QTLs harbored genes associated with blood lipid levels and abnormal lipid metabolism in human genome-wide association studies. Lipid species from different classes provided signatures of metabolic health, including seven plasma triglyceride species that associated with either healthy or fatty liver. This observation was further validated in an independent mouse model of non-alcoholic fatty liver disease (NAFLD) and in plasma from NAFLD patients. This work provides a resource to identify plausible genes regulating the measured lipid species and their association with metabolic traits.


Subject(s)
Lipid Metabolism/genetics , Lipid Metabolism/physiology , Lipids/genetics , Adult , Animals , Cohort Studies , Diet, High-Fat , Disease Models, Animal , Female , Gene Expression Regulation/genetics , Genome-Wide Association Study , Humans , Lipids/blood , Lipids/physiology , Liver/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Middle Aged , Non-alcoholic Fatty Liver Disease/genetics , Prospective Studies , Quantitative Trait Loci , Triglycerides/metabolism
10.
Cell Syst ; 6(6): 722-733.e6, 2018 06 27.
Article in English | MEDLINE | ID: mdl-29909277

ABSTRACT

The genetics of individual lipid species and their relevance in disease is largely unresolved. We profiled a subset of storage, signaling, membrane, and mitochondrial liver lipids across 385 mice from 47 strains of the BXD mouse population fed chow or high-fat diet and integrated these data with complementary multi-omics datasets. We identified several lipid species and lipid clusters with specific phenotypic and molecular signatures and, in particular, cardiolipin species with signatures of healthy and fatty liver. Genetic analyses revealed quantitative trait loci for 68% of the lipids (lQTL). By multi-layered omics analyses, we show the reliability of lQTLs to uncover candidate genes that can regulate the levels of lipid species. Additionally, we identified lQTLs that mapped to genes associated with abnormal lipid metabolism in human GWASs. This work provides a foundation and resource for understanding the genetic regulation and physiological significance of lipid species.


Subject(s)
Lipids/genetics , Liver/chemistry , Liver/metabolism , Animals , Diet, High-Fat , Female , Gene Expression Regulation/genetics , Genome-Wide Association Study/methods , Lipid Metabolism/physiology , Lipids/classification , Male , Mice , Mice, Inbred C57BL , Mice, Inbred DBA , Non-alcoholic Fatty Liver Disease/genetics , Phenotype , Quantitative Trait Loci , Reproducibility of Results , Systems Analysis
11.
Cell Chem Biol ; 25(2): 154-165.e11, 2018 02 15.
Article in English | MEDLINE | ID: mdl-29198567

ABSTRACT

Human COQ8A (ADCK3) and Saccharomyces cerevisiae Coq8p (collectively COQ8) are UbiB family proteins essential for mitochondrial coenzyme Q (CoQ) biosynthesis. However, the biochemical activity of COQ8 and its direct role in CoQ production remain unclear, in part due to lack of known endogenous regulators of COQ8 function and of effective small molecules for probing its activity in vivo. Here, we demonstrate that COQ8 possesses evolutionarily conserved ATPase activity that is activated by binding to membranes containing cardiolipin and by phenolic compounds that resemble CoQ pathway intermediates. We further create an analog-sensitive version of Coq8p and reveal that acute chemical inhibition of its endogenous activity in yeast is sufficient to cause respiratory deficiency concomitant with CoQ depletion. Collectively, this work defines lipid and small-molecule modulators of an ancient family of atypical kinase-like proteins and establishes a chemical genetic system for further exploring the mechanistic role of COQ8 in CoQ biosynthesis.


Subject(s)
Lipids/chemistry , Mitochondrial Proteins/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Small Molecule Libraries/metabolism , Adenosine Triphosphatases/metabolism , Humans , Mitochondrial Proteins/chemistry , Models, Molecular , Molecular Structure , Saccharomyces cerevisiae/chemistry , Saccharomyces cerevisiae/metabolism , Saccharomyces cerevisiae Proteins/chemistry , Small Molecule Libraries/chemistry
12.
Cell Syst ; 6(1): 125-135.e6, 2018 Jan 24.
Article in English | MEDLINE | ID: mdl-29248374

ABSTRACT

Coenzyme Q (CoQ) is a redox-active lipid required for mitochondrial oxidative phosphorylation (OxPhos). How CoQ biosynthesis is coordinated with the biogenesis of OxPhos protein complexes is unclear. Here, we show that the Saccharomyces cerevisiae RNA-binding protein (RBP) Puf3p regulates CoQ biosynthesis. To establish the mechanism for this regulation, we employed a multi-omic strategy to identify mRNAs that not only bind Puf3p but also are regulated by Puf3p in vivo. The CoQ biosynthesis enzyme Coq5p is a critical Puf3p target: Puf3p regulates the abundance of Coq5p and prevents its detrimental hyperaccumulation, thereby enabling efficient CoQ production. More broadly, Puf3p represses a specific set of proteins involved in mitochondrial protein import, translation, and OxPhos complex assembly (pathways essential to prime mitochondrial biogenesis). Our data reveal a mechanism for post-transcriptionally coordinating CoQ production with OxPhos biogenesis, and they demonstrate the power of multi-omics for defining genuine targets of RBPs.


Subject(s)
RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolism , Mitochondria/enzymology , Organelle Biogenesis , Oxidative Phosphorylation , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/genetics , Ubiquinone/biosynthesis
13.
Mol Cell ; 68(5): 970-977.e11, 2017 Dec 07.
Article in English | MEDLINE | ID: mdl-29220658

ABSTRACT

Mitoproteases are becoming recognized as key regulators of diverse mitochondrial functions, although their direct substrates are often difficult to discern. Through multi-omic profiling of diverse Saccharomyces cerevisiae mitoprotease deletion strains, we predicted numerous associations between mitoproteases and distinct mitochondrial processes. These include a strong association between the mitochondrial matrix octapeptidase Oct1p and coenzyme Q (CoQ) biosynthesis-a pathway essential for mitochondrial respiration. Through Edman sequencing and in vitro and in vivo biochemistry, we demonstrated that Oct1p directly processes the N terminus of the CoQ-related methyltransferase, Coq5p, which markedly improves its stability. A single mutation to the Oct1p recognition motif in Coq5p disrupted its processing in vivo, leading to CoQ deficiency and respiratory incompetence. This work defines the Oct1p processing of Coq5p as an essential post-translational event for proper CoQ production. Additionally, our data visualization tool enables efficient exploration of mitoprotease profiles that can serve as the basis for future mechanistic investigations.


Subject(s)
Aminopeptidases/metabolism , Energy Metabolism , Metabolomics/methods , Methyltransferases/metabolism , Mitochondria/enzymology , Proteomics/methods , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/enzymology , Ubiquinone/biosynthesis , Aminopeptidases/genetics , Enzyme Stability , Genotype , Methyltransferases/genetics , Mutation , Phenotype , Protein Domains , Protein Processing, Post-Translational , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics , Time Factors , Ubiquinone/genetics
14.
Cell Rep ; 18(2): 307-313, 2017 01 10.
Article in English | MEDLINE | ID: mdl-28076776

ABSTRACT

Proper maintenance of mitochondrial activity is essential for metabolic homeostasis. Widespread phosphorylation of mitochondrial proteins may be an important element of this process; yet, little is known about which enzymes control mitochondrial phosphorylation or which phosphosites have functional impact. We investigate these issues by disrupting Ptc7p, a conserved but largely uncharacterized mitochondrial matrix PP2C-type phosphatase. Loss of Ptc7p causes respiratory growth defects concomitant with elevated phosphorylation of select matrix proteins. Among these, Δptc7 yeast exhibit an increase in phosphorylation of Cit1p, the canonical citrate synthase of the tricarboxylic acid (TCA) cycle, that diminishes its activity. We find that phosphorylation of S462 can eliminate Cit1p enzymatic activity likely by disrupting its proper dimerization, and that Ptc7p-driven dephosphorylation rescues Cit1p activity. Collectively, our work connects Ptc7p to an essential TCA cycle function and to additional phosphorylation events that may affect mitochondrial activity inadvertently or in a regulatory manner.


Subject(s)
Mitochondrial Proteins/metabolism , Protein Phosphatase 2/metabolism , Saccharomyces cerevisiae Proteins/metabolism , Saccharomyces cerevisiae/metabolism , Aerobiosis , Phosphoproteins/metabolism , Phosphorylation , Phosphoserine/metabolism , Protein Multimerization , Proteomics , Substrate Specificity
15.
Nat Biotechnol ; 34(11): 1191-1197, 2016 Nov.
Article in English | MEDLINE | ID: mdl-27669165

ABSTRACT

Mitochondrial dysfunction is associated with many human diseases, including cancer and neurodegeneration, that are often linked to proteins and pathways that are not well-characterized. To begin defining the functions of such poorly characterized proteins, we used mass spectrometry to map the proteomes, lipidomes, and metabolomes of 174 yeast strains, each lacking a single gene related to mitochondrial biology. 144 of these genes have human homologs, 60 of which are associated with disease and 39 of which are uncharacterized. We present a multi-omic data analysis and visualization tool that we use to find covariance networks that can predict molecular functions, correlations between profiles of related gene deletions, gene-specific perturbations that reflect protein functions, and a global respiration deficiency response. Using this multi-omic approach, we link seven proteins including Hfd1p and its human homolog ALDH3A1 to mitochondrial coenzyme Q (CoQ) biosynthesis, an essential pathway disrupted in many human diseases. This Resource should provide molecular insights into mitochondrial protein functions.


Subject(s)
Gene Expression Profiling/methods , Mass Spectrometry , Mitochondrial Diseases/metabolism , Mitochondrial Proteins/metabolism , Proteome/metabolism , Cells, Cultured , Humans , Metabolome/physiology , Mitochondrial Diseases/genetics , Mitochondrial Proteins/genetics , Peptide Mapping , Proteome/genetics , Signal Transduction
16.
Mol Cell ; 63(4): 621-632, 2016 08 18.
Article in English | MEDLINE | ID: mdl-27499296

ABSTRACT

Mitochondria are essential for numerous cellular processes, yet hundreds of their proteins lack robust functional annotation. To reveal functions for these proteins (termed MXPs), we assessed condition-specific protein-protein interactions for 50 select MXPs using affinity enrichment mass spectrometry. Our data connect MXPs to diverse mitochondrial processes, including multiple aspects of respiratory chain function. Building upon these observations, we validated C17orf89 as a complex I (CI) assembly factor. Disruption of C17orf89 markedly reduced CI activity, and its depletion is found in an unresolved case of CI deficiency. We likewise discovered that LYRM5 interacts with and deflavinates the electron-transferring flavoprotein that shuttles electrons to coenzyme Q (CoQ). Finally, we identified a dynamic human CoQ biosynthetic complex involving multiple MXPs whose topology we map using purified components. Collectively, our data lend mechanistic insight into respiratory chain-related activities and prioritize hundreds of additional interactions for further exploration of mitochondrial protein function.


Subject(s)
Electron Transport Chain Complex Proteins/metabolism , Mitochondria/metabolism , Mitochondrial Proteins/metabolism , Protein Interaction Mapping/methods , Protein Interaction Maps , Proteomics/methods , Databases, Protein , Electron Transport Chain Complex Proteins/genetics , Electron Transport Complex I/metabolism , HEK293 Cells , Hep G2 Cells , Humans , Mitochondrial Proteins/genetics , RNA Interference , Signal Transduction , Transfection , Ubiquinone/metabolism
17.
Mol Cell ; 63(4): 608-620, 2016 08 18.
Article in English | MEDLINE | ID: mdl-27499294

ABSTRACT

The UbiB protein kinase-like (PKL) family is widespread, comprising one-quarter of microbial PKLs and five human homologs, yet its biochemical activities remain obscure. COQ8A (ADCK3) is a mammalian UbiB protein associated with ubiquinone (CoQ) biosynthesis and an ataxia (ARCA2) through unclear means. We show that mice lacking COQ8A develop a slowly progressive cerebellar ataxia linked to Purkinje cell dysfunction and mild exercise intolerance, recapitulating ARCA2. Interspecies biochemical analyses show that COQ8A and yeast Coq8p specifically stabilize a CoQ biosynthesis complex through unorthodox PKL functions. Although COQ8 was predicted to be a protein kinase, we demonstrate that it lacks canonical protein kinase activity in trans. Instead, COQ8 has ATPase activity and interacts with lipid CoQ intermediates, functions that are likely conserved across all domains of life. Collectively, our results lend insight into the molecular activities of the ancient UbiB family and elucidate the biochemical underpinnings of a human disease.


Subject(s)
Behavior, Animal , Cerebellar Ataxia/enzymology , Cerebellum/enzymology , Mitochondrial Proteins/deficiency , Muscle, Skeletal/enzymology , Ubiquinone/deficiency , Animals , COS Cells , Cerebellar Ataxia/genetics , Cerebellar Ataxia/physiopathology , Cerebellar Ataxia/psychology , Cerebellum/physiopathology , Cerebellum/ultrastructure , Chlorocebus aethiops , Disease Models, Animal , Exercise Tolerance , Female , Genetic Predisposition to Disease , HEK293 Cells , Humans , Lipid Metabolism , Male , Maze Learning , Mice, Inbred C57BL , Mice, Knockout , Mitochondrial Proteins/chemistry , Mitochondrial Proteins/genetics , Models, Molecular , Motor Activity , Muscle Strength , Muscle, Skeletal/physiopathology , Phenotype , Protein Binding , Protein Conformation , Proteomics/methods , Recognition, Psychology , Rotarod Performance Test , Saccharomyces cerevisiae/enzymology , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae Proteins/genetics , Saccharomyces cerevisiae Proteins/metabolism , Seizures/enzymology , Seizures/genetics , Seizures/physiopathology , Structure-Activity Relationship , Time Factors , Transfection , Ubiquinone/chemistry , Ubiquinone/genetics
18.
Mol Cell ; 57(1): 83-94, 2015 Jan 08.
Article in English | MEDLINE | ID: mdl-25498144

ABSTRACT

The ancient UbiB protein kinase-like family is involved in isoprenoid lipid biosynthesis and is implicated in human diseases, but demonstration of UbiB kinase activity has remained elusive for unknown reasons. Here, we quantitatively define UbiB-specific sequence motifs and reveal their positions within the crystal structure of a UbiB protein, ADCK3. We find that multiple UbiB-specific features are poised to inhibit protein kinase activity, including an N-terminal domain that occupies the typical substrate binding pocket and a unique A-rich loop that limits ATP binding by establishing an unusual selectivity for ADP. A single alanine-to-glycine mutation of this loop flips this coenzyme selectivity and enables autophosphorylation but inhibits coenzyme Q biosynthesis in vivo, demonstrating functional relevance for this unique feature. Our work provides mechanistic insight into UbiB enzyme activity and establishes a molecular foundation for further investigation of how UbiB family proteins affect diseases and diverse biological pathways.


Subject(s)
Mitochondria/chemistry , Mitochondrial Proteins/chemistry , Ubiquinone/chemistry , Amino Acid Sequence , Crystallography, X-Ray , Escherichia coli/genetics , Escherichia coli/metabolism , Gene Expression , Humans , Mitochondria/metabolism , Mitochondrial Proteins/genetics , Mitochondrial Proteins/metabolism , Models, Molecular , Molecular Sequence Data , Mutation , Phosphorylation , Protein Folding , Protein Structure, Secondary , Protein Structure, Tertiary , Recombinant Proteins/chemistry , Recombinant Proteins/genetics , Recombinant Proteins/metabolism , Saccharomyces cerevisiae/growth & development , Saccharomyces cerevisiae/metabolism , Sequence Alignment , Ubiquinone/biosynthesis
19.
Comp Med ; 64(5): 351-9, 2014 Oct.
Article in English | MEDLINE | ID: mdl-25402175

ABSTRACT

Alterations in the Wnt signaling pathway are associated with diverse cancers, including hepatocellular carcinoma (HCC). The development of HCC is thought to be a multistage process in which multiple genetic alterations are necessary. Few studies have assessed the effect of aberrant Wnt signaling activity in association with other molecular alterations in HCC. Here we sought to determine whether co-overexpression of c-Myc or TGFα, 2 signaling molecules known to contribute to HCC development, enhanced the development of hepatic lesions associated with a stabilized ß-catenin. The coexpression of mutant ß-catenin with either c-Myc or TGFα within hepatocytes increased the severity of hepatic lesions compared with that associated with any of the transgenes expressed individually. The coexpression of mutant ß-catenin with c-Myc or TGFα resulted in severe hepatomegaly necessitating the euthanasia of mice by an average of 156 and 128 d, respectively, after the cessation of doxycycline. The expression of mutant ß-catenin alone resulted in mild to moderate hepatomegaly that prompted the euthanasia of mice by an average of 75 d after the cessation of doxycycline. Collectively, these findings indicate that coexpression of c-Myc or TGFα delays the onset of endstage hepatic disease yet enhances the severity of hepatic lesions due to mutant ß-catenin.


Subject(s)
Carcinoma, Hepatocellular/metabolism , Hepatomegaly/metabolism , Liver Neoplasms/metabolism , Proto-Oncogene Proteins c-myc/metabolism , Transforming Growth Factor alpha/metabolism , Wnt Signaling Pathway/physiology , beta Catenin/metabolism , Analysis of Variance , Animals , Breeding/methods , Carcinoma, Hepatocellular/pathology , Hepatomegaly/chemically induced , Immunohistochemistry , Kaplan-Meier Estimate , Liver/pathology , Liver Neoplasms/pathology , Mice , Mice, Transgenic , Polymerase Chain Reaction , beta Catenin/adverse effects , beta Catenin/genetics
20.
Proc Natl Acad Sci U S A ; 111(44): E4697-705, 2014 Nov 04.
Article in English | MEDLINE | ID: mdl-25339443

ABSTRACT

Coenzyme Q (CoQ) is an isoprenylated quinone that is essential for cellular respiration and is synthesized in mitochondria by the combined action of at least nine proteins (COQ1-9). Although most COQ proteins are known to catalyze modifications to CoQ precursors, the biochemical role of COQ9 remains unclear. Here, we report that a disease-related COQ9 mutation leads to extensive disruption of the CoQ protein biosynthetic complex in a mouse model, and that COQ9 specifically interacts with COQ7 through a series of conserved residues. Toward understanding how COQ9 can perform these functions, we solved the crystal structure of Homo sapiens COQ9 at 2.4 Å. Unexpectedly, our structure reveals that COQ9 has structural homology to the TFR family of bacterial transcriptional regulators, but that it adopts an atypical TFR dimer orientation and is not predicted to bind DNA. Our structure also reveals a lipid-binding site, and mass spectrometry-based analyses of purified COQ9 demonstrate that it associates with multiple lipid species, including CoQ itself. The conserved COQ9 residues necessary for its interaction with COQ7 comprise a surface patch around the lipid-binding site, suggesting that COQ9 might serve to present its bound lipid to COQ7. Collectively, our data define COQ9 as the first, to our knowledge, mammalian TFR structural homolog and suggest that its lipid-binding capacity and association with COQ7 are key features for enabling CoQ biosynthesis.


Subject(s)
Carrier Proteins/chemistry , Carrier Proteins/metabolism , Lipid Metabolism/physiology , Membrane Proteins/chemistry , Membrane Proteins/metabolism , Mitochondrial Proteins/chemistry , Mitochondrial Proteins/metabolism , Ubiquinone/biosynthesis , Animals , Carrier Proteins/genetics , Crystallography, X-Ray , Humans , Membrane Proteins/genetics , Mice , Mice, Mutant Strains , Mitochondrial Proteins/genetics , Mixed Function Oxygenases , Protein Structure, Tertiary , Ubiquinone/genetics
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