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1.
Genome Biol Evol ; 2024 Jun 24.
Article in English | MEDLINE | ID: mdl-38913570

ABSTRACT

Vertebrate evolution has been punctuated by three whole genome duplication (WGD) events that have been implicated causally in phenotypic evolution, from the origin of phenotypic novelties to explosive diversification. Arguably the most dramatic of these is the 3R WGD event associated with the origin of teleost fishes which comprise more than half of all living vertebrate species. However, tests of a causal relationship between WGD and teleost diversification have proven difficult due to the challenge of establishing the timing of these phenomena. Here we show, based on molecular clock dating of concatenated gene alignments, that the 3R WGD event occurred in the early-middle Permian (286.18-267.20 Million years ago; Ma), 52.02-12.84 million years (Myr) before the divergence of crown-teleosts in the latest-Permian-earliest Late Triassic (254.36-234.16 Ma) and long before the major pulses of teleost diversification in Ostariophysi and Percomorpha (56.37-100.17 Myr and at least 139.24-183.29 Myr later, respectively). The extent of this temporal gap between putative cause and effect precludes 3R as a deterministic driver of teleost diversification. However, these age constraints remain compatible with the expectations of a prolonged rediploidization process following WGD which, through the effects of chromosome rearrangement and gene loss, remains a viable mechanism to explain the evolution of teleost novelties and diversification.

2.
Elife ; 132024 May 23.
Article in English | MEDLINE | ID: mdl-38780415

ABSTRACT

Stramenopiles form a clade of diverse eukaryotic organisms, including multicellular algae, the fish and plant pathogenic oomycetes, such as the potato blight Phytophthora, and the human intestinal protozoan Blastocystis. In most eukaryotes, glycolysis is a strictly cytosolic metabolic pathway that converts glucose to pyruvate, resulting in the production of NADH and ATP (Adenosine triphosphate). In contrast, stramenopiles have a branched glycolysis in which the enzymes of the pay-off phase are located in both the cytosol and the mitochondrial matrix. Here, we identify a mitochondrial carrier in Blastocystis that can transport glycolytic intermediates, such as dihydroxyacetone phosphate and glyceraldehyde-3-phosphate, across the mitochondrial inner membrane, linking the cytosolic and mitochondrial branches of glycolysis. Comparative analyses with the phylogenetically related human mitochondrial oxoglutarate carrier (SLC25A11) and dicarboxylate carrier (SLC25A10) show that the glycolytic intermediate carrier has lost its ability to transport the canonical substrates malate and oxoglutarate. Blastocystis lacks several key components of oxidative phosphorylation required for the generation of mitochondrial ATP, such as complexes III and IV, ATP synthase, and ADP/ATP carriers. The presence of the glycolytic pay-off phase in the mitochondrial matrix generates ATP, which powers energy-requiring processes, such as macromolecular synthesis, as well as NADH, used by mitochondrial complex I to generate a proton motive force to drive the import of proteins and molecules. Given its unique substrate specificity and central role in carbon and energy metabolism, the carrier for glycolytic intermediates identified here represents a specific drug and pesticide target against stramenopile pathogens, which are of great economic importance.


All living organisms breakdown food molecules to generate energy for processes, such as growing, reproducing and movement. The series of chemical reactions that breakdown sugars into smaller molecules ­ known as glycolysis ­ is so important that it occurs in all life forms, from bacteria to humans. In higher organisms, such as fungi and animals, these reactions take place in the cytosol, the space surrounding the cell's various compartments. A transport protein then shuttles the end-product of glycolysis ­ pyruvate ­ into specialised compartments, known as the mitochondria, where most energy is produced. However, recently it was discovered that a group of living organisms, called the stramenopiles, have a branched glycolysis in which the enzymes involved in the second half of this process are located in both the cytosol and mitochondrial matrix. But it was not known how the intermediate molecules produced after the first half of glycolysis enter the mitochondria. To answer this question, Pyrihová et al. searched for transport protein(s) that could link the two halves of the glycolysis pathway. Computational analyses, comparing the genetic sequences of many transport proteins from several different species, revealed a new group found only in stramenopiles. Pyrihová et al. then used microscopy to visualise these new transport proteins ­ called GIC-1 and GIC-2 ­ in the parasite Blastocystis, which infects the human gut, and observed that they localise to mitochondria. Further biochemical experiments showed that GIC-1 and GIC-2 can physically bind these intermediate molecules, but only GIC-2 can transport them across membranes. Taken together, these observations suggest that GIC-2 links the two halves of glycolysis in Blastocystis. Further analyses could reveal corresponding transport proteins in other stramenopiles, many of which have devastating effects on agriculture, such as Phytophthora, which causes potato blight, or Saprolegnia, which causes skin infections in farmed salmon. Since human cells do not have equivalent transporters, they could be new drug targets not only for Blastocystis, but for these harmful pathogens as well.


Subject(s)
Blastocystis , Cytosol , Glycolysis , Mitochondria , Blastocystis/metabolism , Blastocystis/genetics , Humans , Mitochondria/metabolism , Cytosol/metabolism , Biological Transport , Protozoan Proteins/metabolism , Protozoan Proteins/genetics
3.
Trends Biochem Sci ; 49(6): 506-519, 2024 Jun.
Article in English | MEDLINE | ID: mdl-38565497

ABSTRACT

In mitochondria, the oxidation of nutrients is coupled to ATP synthesis by the generation of a protonmotive force across the mitochondrial inner membrane. In mammalian brown adipose tissue (BAT), uncoupling protein 1 (UCP1, SLC25A7), a member of the SLC25 mitochondrial carrier family, dissipates the protonmotive force by facilitating the return of protons to the mitochondrial matrix. This process short-circuits the mitochondrion, generating heat for non-shivering thermogenesis. Recent cryo-electron microscopy (cryo-EM) structures of human UCP1 have provided new molecular insights into the inhibition and activation of thermogenesis. Here, we discuss these structures, describing how purine nucleotides lock UCP1 in a proton-impermeable conformation and rationalizing potential conformational changes of this carrier in response to fatty acid activators that enable proton leak for thermogenesis.


Subject(s)
Thermogenesis , Uncoupling Protein 1 , Humans , Uncoupling Protein 1/metabolism , Animals , Mitochondria/metabolism , Adipose Tissue, Brown/metabolism
4.
Br J Pharmacol ; 180 Suppl 2: S374-S469, 2023 10.
Article in English | MEDLINE | ID: mdl-38123156

ABSTRACT

The Concise Guide to PHARMACOLOGY 2023/24 is the sixth in this series of biennial publications. The Concise Guide provides concise overviews, mostly in tabular format, of the key properties of approximately 1800 drug targets, and over 6000 interactions with about 3900 ligands. There is an emphasis on selective pharmacology (where available), plus links to the open access knowledgebase source of drug targets and their ligands (https://www.guidetopharmacology.org/), which provides more detailed views of target and ligand properties. Although the Concise Guide constitutes almost 500 pages, the material presented is substantially reduced compared to information and links presented on the website. It provides a permanent, citable, point-in-time record that will survive database updates. The full contents of this section can be found at http://onlinelibrary.wiley.com/doi/10.1111/bph.16182. Transporters are one of the six major pharmacological targets into which the Guide is divided, with the others being: G protein-coupled receptors, ion channels, nuclear hormone receptors, catalytic receptors and enzymes. These are presented with nomenclature guidance and summary information on the best available pharmacological tools, alongside key references and suggestions for further reading. The landscape format of the Concise Guide is designed to facilitate comparison of related targets from material contemporary to mid-2023, and supersedes data presented in the 2021/22, 2019/20, 2017/18, 2015/16 and 2013/14 Concise Guides and previous Guides to Receptors and Channels. It is produced in close conjunction with the Nomenclature and Standards Committee of the International Union of Basic and Clinical Pharmacology (NC-IUPHAR), therefore, providing official IUPHAR classification and nomenclature for human drug targets, where appropriate.


Subject(s)
Databases, Pharmaceutical , Pharmacology , Humans , Ligands , Ion Channels/chemistry , Receptors, G-Protein-Coupled , Receptors, Cytoplasmic and Nuclear
5.
Nat Commun ; 14(1): 7456, 2023 11 17.
Article in English | MEDLINE | ID: mdl-37978174

ABSTRACT

The timing of early cellular evolution, from the divergence of Archaea and Bacteria to the origin of eukaryotes, is poorly constrained. The ATP synthase complex is thought to have originated prior to the Last Universal Common Ancestor (LUCA) and analyses of ATP synthase genes, together with ribosomes, have played a key role in inferring and rooting the tree of life. We reconstruct the evolutionary history of ATP synthases using an expanded taxon sampling set and develop a phylogenetic cross-bracing approach, constraining equivalent speciation nodes to be contemporaneous, based on the phylogenetic imprint of endosymbioses and ancient gene duplications. This approach results in a highly resolved, dated species tree and establishes an absolute timeline for ATP synthase evolution. Our analyses show that the divergence of ATP synthase into F- and A/V-type lineages was a very early event in cellular evolution dating back to more than 4 Ga, potentially predating the diversification of Archaea and Bacteria. Our cross-braced, dated tree of life also provides insight into more recent evolutionary transitions including eukaryogenesis, showing that the eukaryotic nuclear and mitochondrial lineages diverged from their closest archaeal (2.67-2.19 Ga) and bacterial (2.58-2.12 Ga) relatives at approximately the same time, with a slightly longer nuclear stem-lineage.


Subject(s)
Archaea , Bacteria , Phylogeny , Bacteria/genetics , Archaea/genetics , Mitochondria/genetics , Adenosine Triphosphate , Evolution, Molecular , Eukaryota/genetics , Biological Evolution
6.
mBio ; : e0227223, 2023 Nov 15.
Article in English | MEDLINE | ID: mdl-37966230

ABSTRACT

IMPORTANCE: Protein filaments play important roles in many biological processes. We discovered an actin homolog in halophilic archaea, which we call Salactin. Just like the filaments that segregate DNA in eukaryotes, Salactin grows out of the cell poles towards the middle, and then quickly depolymerizes, a behavior known as dynamic instability. Furthermore, we see that Salactin affects the distribution of DNA in daughter cells when cells are grown in low-phosphate media, suggesting Salactin filaments might be involved in segregating DNA when the cell has only a few copies of the chromosome.

7.
Curr Biol ; 33(17): R919-R929, 2023 09 11.
Article in English | MEDLINE | ID: mdl-37699353

ABSTRACT

The origin of eukaryotes is among the most contentious debates in evolutionary biology, attracting multiple seemingly incompatible theories seeking to explain the sequence in which eukaryotic characteristics were acquired. Much of the controversy arises from differing views on the defining characteristics of eukaryotes. We argue that eukaryotes should be defined phylogenetically, and that doing so clarifies where competing hypotheses of eukaryogenesis agree and how we may test among aspects of disagreement. Some hypotheses make predictions about the phylogenetic origins of eukaryotic genes and are distinguishable on that basis. However, other hypotheses differ only in the order of key evolutionary steps, like mitochondrial endosymbiosis and nuclear assembly, which cannot currently be distinguished phylogenetically. Stages within eukaryogenesis may be made identifiable through the absolute dating of gene duplicates that map to eukaryotic traits, such as in genes of host or mitochondrial origin that duplicated and diverged functionally prior to emergence of the last eukaryotic common ancestor. In this way, it may finally be possible to distinguish heat from light in the debate over eukaryogenesis.


Subject(s)
Eukaryota , Eukaryotic Cells , Eukaryota/genetics , Phylogeny , Biological Evolution , Dissent and Disputes
8.
Acta Physiol (Oxf) ; 238(4): e14016, 2023 08.
Article in English | MEDLINE | ID: mdl-37366179

ABSTRACT

The mitochondrial pyruvate carrier (MPC) resides in the mitochondrial inner membrane, where it links cytosolic and mitochondrial metabolism by transporting pyruvate produced in glycolysis into the mitochondrial matrix. Due to its central metabolic role, it has been proposed as a potential drug target for diabetes, non-alcoholic fatty liver disease, neurodegeneration, and cancers relying on mitochondrial metabolism. Little is known about the structure and mechanism of MPC, as the proteins involved were only identified a decade ago and technical difficulties concerning their purification and stability have hindered progress in functional and structural analyses. The functional unit of MPC is a hetero-dimer comprising two small homologous membrane proteins, MPC1/MPC2 in humans, with the alternative complex MPC1L/MPC2 forming in the testis, but MPC proteins are found throughout the tree of life. The predicted topology of each protomer consists of an amphipathic helix followed by three transmembrane helices. An increasing number of inhibitors are being identified, expanding MPC pharmacology and providing insights into the inhibitory mechanism. Here, we provide critical insights on the composition, structure, and function of the complex and we summarize the different classes of small molecule inhibitors and their potential in therapeutics.


Subject(s)
Mitochondrial Membrane Transport Proteins , Monocarboxylic Acid Transporters , Male , Humans , Monocarboxylic Acid Transporters/metabolism , Mitochondrial Membrane Transport Proteins/chemistry , Mitochondrial Membrane Transport Proteins/metabolism , Mitochondria/metabolism , Mitochondrial Membranes/metabolism , Mitochondrial Proteins/metabolism , Pyruvic Acid/metabolism
9.
Med Care ; 61(6): 360-365, 2023 06 01.
Article in English | MEDLINE | ID: mdl-37167557

ABSTRACT

BACKGROUND: Clostridioides difficile is the leading cause of hospital-onset diarrhea and is associated with increased lengths of stay and mortality. While some hospitals have successfully reduced the burden of C. difficile infection (CDI), many still struggle to reduce hospital-onset CDI. Nurses-because of their close proximity to patients-are an important resource in the prevention of hospital-onset CDI. OBJECTIVE: Determine whether there is an association between the nurse work environment and hospital-onset CDI. METHODS: Survey data of 2016 were available from 15,982 nurses employed in 353 acute care hospitals. These data, aggregated to the hospital level, provided measures of the nurse work environments. They were merged with 2016 hospital-onset CDI data from Hospital Compare, which provided our outcome measure-whether a hospital had a standardized infection ratio (SIR) above or below the national average SIR. Hospitals above the average SIR had more infections than predicted when compared to the national average. RESULTS: In all, 188 hospitals (53%) had SIRs higher than the national average. The odds of hospitals having higher than average SIRs were significantly lower, with odds ratios ranging from 0.35 to 0.45, in hospitals in the highest quartile for all four nurse work environment subscales (managerial support, nurse participation in hospital governance, physician-nurse relations, and adequate staffing) than in hospitals in the lowest quartile. CONCLUSIONS: Findings show an association between the work environment of nurses and hospital-onset CDI. A promising strategy to lower hospital-onset CDI and other infections is a serious and sustained commitment by hospital leaders to significantly improve nurse work environments.


Subject(s)
Clostridioides difficile , Clostridium Infections , Cross Infection , Humans , Working Conditions , Hospitals , Clostridium Infections/epidemiology , Clostridium Infections/prevention & control , Cross Infection/epidemiology , Cross Infection/prevention & control
10.
Arch Biochem Biophys ; 742: 109638, 2023 07 01.
Article in English | MEDLINE | ID: mdl-37192692

ABSTRACT

Paratrimastix pyriformis is a free-living flagellate thriving in low-oxygen freshwater sediments. It belongs to the group Metamonada along with human parasites, such as Giardia and Trichomonas. Like other metamonads, P. pyriformis has a mitochondrion-related organelle (MRO) which in this protist is primarily involved in one-carbon folate metabolism. The MRO contains four members of the solute carrier family 25 (SLC25) responsible for the exchange of metabolites across the mitochondrial inner membrane. Here, we characterise the function of the adenine nucleotide carrier PpMC1 by thermostability shift and transport assays. We show that it transports ATP, ADP and, to a lesser extent, AMP, but not phosphate. The carrier is distinct in function and origin from both ADP/ATP carriers and ATP-Mg/phosphate carriers, and it most likely represents a distinct class of adenine nucleotide carriers.


Subject(s)
Parasites , Animals , Humans , Parasites/metabolism , Mitochondria/metabolism , Adenosine Monophosphate/metabolism , Mitochondrial Membranes/metabolism , Adenosine Triphosphate/metabolism
11.
Cell ; 186(10): 2219-2237.e29, 2023 05 11.
Article in English | MEDLINE | ID: mdl-37172566

ABSTRACT

The Commander complex is required for endosomal recycling of diverse transmembrane cargos and is mutated in Ritscher-Schinzel syndrome. It comprises two sub-assemblies: Retriever composed of VPS35L, VPS26C, and VPS29; and the CCC complex which contains twelve subunits: COMMD1-COMMD10 and the coiled-coil domain-containing (CCDC) proteins CCDC22 and CCDC93. Combining X-ray crystallography, electron cryomicroscopy, and in silico predictions, we have assembled a complete structural model of Commander. Retriever is distantly related to the endosomal Retromer complex but has unique features preventing the shared VPS29 subunit from interacting with Retromer-associated factors. The COMMD proteins form a distinctive hetero-decameric ring stabilized by extensive interactions with CCDC22 and CCDC93. These adopt a coiled-coil structure that connects the CCC and Retriever assemblies and recruits a 16th subunit, DENND10, to form the complete Commander complex. The structure allows mapping of disease-causing mutations and reveals the molecular features required for the function of this evolutionarily conserved trafficking machinery.


Subject(s)
Abnormalities, Multiple , Craniofacial Abnormalities , Multiprotein Complexes , Humans , Endosomes/metabolism , Protein Transport , Proteins/metabolism , Multiprotein Complexes/metabolism
12.
Sci Adv ; 9(22): eadh4251, 2023 06 02.
Article in English | MEDLINE | ID: mdl-37256948

ABSTRACT

Mitochondrial uncoupling protein 1 (UCP1) gives brown adipose tissue of mammals its specialized ability to burn calories as heat for thermoregulation. When activated by fatty acids, UCP1 catalyzes the leak of protons across the mitochondrial inner membrane, short-circuiting the mitochondrion to generate heat, bypassing ATP synthesis. In contrast, purine nucleotides bind and inhibit UCP1, regulating proton leak by a molecular mechanism that is unclear. We present the cryo-electron microscopy structure of the GTP-inhibited state of UCP1, which is consistent with its nonconducting state. The purine nucleotide cross-links the transmembrane helices of UCP1 with an extensive interaction network. Our results provide a structural basis for understanding the specificity and pH dependency of the regulatory mechanism. UCP1 has retained all of the key functional and structural features required for a mitochondrial carrier-like transport mechanism. The analysis shows that inhibitor binding prevents the conformational changes that UCP1 uses to facilitate proton leak.


Subject(s)
Ion Channels , Protons , Humans , Cryoelectron Microscopy , Ion Channels/chemistry , Mitochondrial Proteins/metabolism , Purine Nucleotides , Uncoupling Protein 1/genetics , Uncoupling Protein 1/metabolism
13.
Genome Biol Evol ; 15(4)2023 04 06.
Article in English | MEDLINE | ID: mdl-36951100

ABSTRACT

The origin of microbial mercury methylation has long been a mystery. Here, we employed genome-resolved phylogenetic analyses to decipher the evolution of the mercury-methylating gene, hgcAB, constrain the ancestral origin of the hgc operon, and explain the distribution of hgc in Bacteria and Archaea. We infer the extent to which vertical inheritance and horizontal gene transfer have influenced the evolution of mercury methylators and hypothesize that evolution of this trait bestowed the ability to produce an antimicrobial compound (MeHg+) on a potentially resource-limited early Earth. We speculate that, in response, the evolution of MeHg+-detoxifying alkylmercury lyase (encoded by merB) reduced a selective advantage for mercury methylators and resulted in widespread loss of hgc in Bacteria and Archaea.


Subject(s)
Mercury , Methylmercury Compounds , Methylation , Phylogeny , Bacteria/genetics , Archaea/genetics
14.
Neural Regen Res ; 18(2): 364-367, 2023 Feb.
Article in English | MEDLINE | ID: mdl-35900431

ABSTRACT

Therapeutic intervention for spinal cord injury is limited, with many approaches relying on strengthening the remaining substrate and driving recovery through rehabilitative training. As compared with learning novel compensatory strategies, rehabilitation focuses on restoring movements lost to injury. Whether rehabilitation of previously learned movements after spinal cord injury requires the molecular mechanisms of motor learning, or if it engages previously trained motor circuits without requiring novel learning remains an open question. In this study, mice were randomly assigned to receive intraperitoneal injection with the pan-nicotinic, non-competitive antagonist mecamylamine and the nicotinic α7 subunit selective antagonist methyllycaconitine citrate salt or vehicle (normal saline) prior to motor learning assays, then randomly reassigned after motor learning for rehabilitation study post-injury. Cervical spinal cord dorsal column lesion was used as a model of incomplete injury. Results of this study showed that nicotinic acetylcholine signaling was required for motor learning of the single pellet-reaching task but it was dispensable for the rehabilitation of the same task after injury. Our findings indicate that critical differences exist between the molecular mechanisms supporting compensatory motor learning strategies and the restoration of behavior lost to spinal cord injury.

15.
JAMA Health Forum ; 3(5): e221173, 2022 05.
Article in English | MEDLINE | ID: mdl-35977257

ABSTRACT

Importance: Sepsis is a major physiologic response to infection that if not managed properly can lead to multiorgan failure and death. The US Centers for Medicare & Medicaid Services (CMS) requires that hospitals collect data on core sepsis measure Severe Sepsis and Septic Shock Management Bundle (SEP-1) in an effort to promote the early recognition and treatment of sepsis. Despite implementation of the SEP-1 measure, sepsis-related mortality continues to challenge acute care hospitals nationwide. Objective: To determine if registered nurse workload was associated with mortality in Medicare beneficiaries admitted to an acute care hospital with sepsis. Design Setting and Participants: This cross-sectional study used 2018 data from the American Hospital Association Annual Survey, CMS Hospital Compare, and Medicare claims on Medicare beneficiaries age 65 to 99 years with a primary diagnosis of sepsis that was present on admission to 1 of 1958 nonfederal, general acute care hospitals that had data on CMS SEP-1 scores and registered nurse workload (indicated by registered nurse hours per patient day [HPPD]). Patients with sepsis were identified based on 29 International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM) codes. Data were analyzed throughout 2021. Exposures: SEP-1 score and registered nurse staffing. Main Outcomes and Measures: The patient outcome of interest was mortality within 60 days of admission. Hospital characteristics included number of beds, ownership, teaching status, technology status, rurality, and region. Patient characteristics included age, sex, transfer status, intensive care unit admission, palliative care, do-not-resuscitate order, and a series of 29 comorbid diseases based on the Elixhauser Comorbidity Index. Results: In total, 702 140 Medicare beneficiaries (mean [SD] age, 78.2 [8.7] years; 360 804 women [51%]) had a diagnosis of sepsis. The mean SEP-1 score was 56.1, and registered nurse HPPD was 6.2. In a multivariable regression model, each additional registered nurse HPPD was associated with a 3% decrease in the odds of 60-day mortality (odds ratio, 0.97; 95% CI 0.96-0.99) controlling for SEP-1 score and hospital and patient characteristics. Conclusions and Relevance: The results of this cross-sectional study suggest that hospitals that provide more registered nurse hours of care could likely improve SEP-1 bundle compliance and decrease the likelihood of mortality in Medicare beneficiaries with sepsis.


Subject(s)
Nurses , Sepsis , Aged , Aged, 80 and over , Cross-Sectional Studies , Female , Humans , Medicare , Sepsis/diagnosis , United States/epidemiology , Workforce
16.
Mol Metab ; 62: 101526, 2022 08.
Article in English | MEDLINE | ID: mdl-35691529

ABSTRACT

OBJECTIVE: Uncoupling protein 1 (UCP1) catalyses mitochondrial proton leak in brown adipose tissue to facilitate nutrient oxidation for heat production, and may combat metabolic disease if activated in humans. During the adrenergic stimulation of brown adipocytes, free fatty acids generated from lipolysis activate UCP1 via an unclear interaction. Here, we set out to characterise activator binding to purified UCP1 to clarify the activation process, discern novel activators and the potential to target UCP1. METHODS: We assessed ligand binding to purified UCP1 by protein thermostability shift analysis, which unlike many conventional approaches can inform on the binding of hydrophobic ligands to membrane proteins. A detailed activator interaction analysis and screening approach was carried out, supported by investigations of UCP1 activity in liposomes, isolated brown fat mitochondria and UCP1 expression-controlled cell lines. RESULTS: We reveal that fatty acids and other activators influence UCP1 through a specific destabilising interaction, behaving as transport substrates that shift the protein to a less stable conformation of a transport cycle. Through the detection of specific stability shifts in screens, we identify novel activators, including the over-the-counter drug ibuprofen, where ligand analysis indicates that UCP1 has a relatively wide structural specificity for interacting molecules. Ibuprofen successfully induced UCP1 activity in liposomes, isolated brown fat mitochondria and UCP1-expressing HEK293 cells but not in cultured brown adipocytes, suggesting drug delivery differs in each cell type. CONCLUSIONS: These findings clarify the nature of the activator-UCP1 interaction and demonstrate that the targeting of UCP1 in cells by approved drugs is in principle achievable as a therapeutic avenue, but requires variants with more effective delivery in brown adipocytes.


Subject(s)
Liposomes , Membrane Proteins , Uncoupling Protein 1 , HEK293 Cells , Humans , Ibuprofen , Ion Channels/metabolism , Ligands , Liposomes/metabolism , Membrane Proteins/metabolism , Mitochondrial Proteins/metabolism , Uncoupling Protein 1/metabolism
17.
Trends Endocrinol Metab ; 33(8): 539-553, 2022 08.
Article in English | MEDLINE | ID: mdl-35725541

ABSTRACT

Citrin deficiency is a pan-ethnic and highly prevalent mitochondrial disease with three different stages: neonatal intrahepatic cholestasis (NICCD), a relatively mild adaptation stage, and type II citrullinemia in adulthood (CTLN2). The cause is the absence or dysfunction of the calcium-regulated mitochondrial aspartate/glutamate carrier 2 (AGC2/SLC25A13), also called citrin, which imports glutamate into the mitochondrial matrix and exports aspartate to the cytosol. In citrin deficiency, these missing transport steps lead to impairment of the malate-aspartate shuttle, gluconeogenesis, amino acid homeostasis, and the urea cycle. In this review, we describe the geological spread and occurrence of citrin deficiency, the metabolic consequences and use our current knowledge of the structure to predict the impact of the known pathogenic mutations on the calcium-regulatory and transport mechanism of citrin.


Subject(s)
Citrullinemia , Adult , Aspartic Acid/genetics , Calcium , Citrullinemia/genetics , Citrullinemia/metabolism , Glutamates/genetics , Humans , Infant, Newborn , Mitochondrial Membrane Transport Proteins/genetics , Mutation
18.
Nat Commun ; 13(1): 3585, 2022 06 23.
Article in English | MEDLINE | ID: mdl-35739110

ABSTRACT

Mitochondrial ADP/ATP carriers import ADP into the mitochondrial matrix and export ATP to the cytosol to fuel cellular processes. Structures of the inhibited cytoplasmic- and matrix-open states have confirmed an alternating access transport mechanism, but the molecular details of substrate binding remain unresolved. Here, we evaluate the role of the solvent-exposed residues of the translocation pathway in the process of substrate binding. We identify the main binding site, comprising three positively charged and a set of aliphatic and aromatic residues, which bind ADP and ATP in both states. Additionally, there are two pairs of asparagine/arginine residues on opposite sides of this site that are involved in substrate binding in a state-dependent manner. Thus, the substrates are directed through a series of binding poses, inducing the conformational changes of the carrier that lead to their translocation. The properties of this site explain the electrogenic and reversible nature of adenine nucleotide transport.


Subject(s)
Mitochondria , Mitochondrial ADP, ATP Translocases , Adenosine Diphosphate/metabolism , Adenosine Triphosphate/metabolism , Binding Sites , Cytoplasm/metabolism , Mitochondria/metabolism , Mitochondrial ADP, ATP Translocases/chemistry , Mitochondrial ADP, ATP Translocases/metabolism
19.
Brain ; 145(9): 3095-3107, 2022 09 14.
Article in English | MEDLINE | ID: mdl-35718349

ABSTRACT

The hereditary spastic paraplegias (HSP) are among the most genetically diverse of all Mendelian disorders. They comprise a large group of neurodegenerative diseases that may be divided into 'pure HSP' in forms of the disease primarily entailing progressive lower-limb weakness and spasticity, and 'complex HSP' when these features are accompanied by other neurological (or non-neurological) clinical signs. Here, we identified biallelic variants in the transmembrane protein 63C (TMEM63C) gene, encoding a predicted osmosensitive calcium-permeable cation channel, in individuals with hereditary spastic paraplegias associated with mild intellectual disability in some, but not all cases. Biochemical and microscopy analyses revealed that TMEM63C is an endoplasmic reticulum-localized protein, which is particularly enriched at mitochondria-endoplasmic reticulum contact sites. Functional in cellula studies indicate a role for TMEM63C in regulating both endoplasmic reticulum and mitochondrial morphologies. Together, these findings identify autosomal recessive TMEM63C variants as a cause of pure and complex HSP and add to the growing evidence of a fundamental pathomolecular role of perturbed mitochondrial-endoplasmic reticulum dynamics in motor neurone degenerative diseases.


Subject(s)
Calcium Channels , Mitochondria , Spastic Paraplegia, Hereditary , Calcium Channels/genetics , Endoplasmic Reticulum/genetics , Humans , Mitochondria/pathology , Mutation , Spastic Paraplegia, Hereditary/genetics
20.
PLoS Biol ; 20(4): e3001601, 2022 04.
Article in English | MEDLINE | ID: mdl-35417450

ABSTRACT

Coat complexes coordinate cargo recognition through cargo adaptors with biogenesis of transport carriers during integral membrane protein trafficking. Here, we combine biochemical, structural, and cellular analyses to establish the mechanistic basis through which SNX27-Retromer, a major endosomal cargo adaptor, couples to the membrane remodeling endosomal SNX-BAR sorting complex for promoting exit 1 (ESCPE-1). In showing that the SNX27 FERM (4.1/ezrin/radixin/moesin) domain directly binds acidic-Asp-Leu-Phe (aDLF) motifs in the SNX1/SNX2 subunits of ESCPE-1, we propose a handover model where SNX27-Retromer captured cargo proteins are transferred into ESCPE-1 transport carriers to promote endosome-to-plasma membrane recycling. By revealing that assembly of the SNX27:Retromer:ESCPE-1 coat evolved in a stepwise manner during early metazoan evolution, likely reflecting the increasing complexity of endosome-to-plasma membrane recycling from the ancestral opisthokont to modern animals, we provide further evidence of the functional diversification of yeast pentameric Retromer in the recycling of hundreds of integral membrane proteins in metazoans.


Subject(s)
Endosomes , Sorting Nexins , Animals , Cell Membrane/metabolism , Endosomes/metabolism , Protein Transport , Sorting Nexins/metabolism
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