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1.
Nat Commun ; 11(1): 4837, 2020 09 24.
Artigo em Inglês | MEDLINE | ID: mdl-32973183

RESUMO

ATP synthesis and thermogenesis are two critical outputs of mitochondrial respiration. How these outputs are regulated to balance the cellular requirement for energy and heat is largely unknown. Here we show that major facilitator superfamily domain containing 7C (MFSD7C) uncouples mitochondrial respiration to switch ATP synthesis to thermogenesis in response to heme. When heme levels are low, MSFD7C promotes ATP synthesis by interacting with components of the electron transport chain (ETC) complexes III, IV, and V, and destabilizing sarcoendoplasmic reticulum Ca2+-ATPase 2b (SERCA2b). Upon heme binding to the N-terminal domain, MFSD7C dissociates from ETC components and SERCA2b, resulting in SERCA2b stabilization and thermogenesis. The heme-regulated switch between ATP synthesis and thermogenesis enables cells to match outputs of mitochondrial respiration to their metabolic state and nutrient supply, and represents a cell intrinsic mechanism to regulate mitochondrial energy metabolism.


Assuntos
Trifosfato de Adenosina/metabolismo , Heme/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Mitocôndrias/metabolismo , Receptores Virais/metabolismo , Termogênese/fisiologia , Animais , Deficiência de Citocromo-c Oxidase , Complexo III da Cadeia de Transporte de Elétrons , Complexo IV da Cadeia de Transporte de Elétrons , Metabolismo Energético/fisiologia , Técnicas de Inativação de Genes , Células HEK293 , Humanos , Proteínas de Membrana Transportadoras/genética , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Membranas Mitocondriais/metabolismo , Domínios Proteicos , Receptores Virais/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Transdução de Sinais , Células THP-1
2.
Nat Commun ; 11(1): 4192, 2020 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-32826886

RESUMO

Bioluminescence imaging has been widely used in life sciences and biomedical applications. However, conventional bioluminescence imaging usually operates in the visible region, which hampers the high-performance in vivo optical imaging due to the strong tissue absorption and scattering. To address this challenge, here we present bioluminescence probes (BPs) with emission in the second near infrared (NIR-II) region at 1029 nm by employing bioluminescence resonance energy transfer (BRET) and two-step fluorescence resonance energy transfer (FRET) with a specially designed cyanine dye FD-1029. The biocompatible NIR-II-BPs are successfully applied to vessels and lymphatics imaging in mice, which gives ~5 times higher signal-to-noise ratios and ~1.5 times higher spatial resolution than those obtained by NIR-II fluorescence imaging and conventional bioluminescence imaging. Their capability of multiplexed imaging is also well displayed. Taking advantage of the ATP-responding character, the NIR-II-BPs are able to recognize tumor metastasis with a high tumor-to-normal tissue ratio at 83.4.


Assuntos
Trifosfato de Adenosina/metabolismo , Medições Luminescentes/métodos , Metástase Neoplásica/diagnóstico por imagem , Imagem Óptica/métodos , Animais , Técnicas Biossensoriais , Linhagem Celular Tumoral , Feminino , Transferência Ressonante de Energia de Fluorescência/instrumentação , Transferência Ressonante de Energia de Fluorescência/métodos , Xenoenxertos , Humanos , Medições Luminescentes/instrumentação , Camundongos , Imagem Óptica/instrumentação , Neoplasias Ovarianas/diagnóstico por imagem
3.
PLoS One ; 15(8): e0237569, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32817667

RESUMO

Several 'super-complexes' of individual hetero-oligomeric membrane protein complexes, whose function is to facilitate intra-membrane electron and proton transfer and harvesting of light energy, have been previously characterized in the mitochondrial cristae and chloroplast thylakoid membranes. We report the presence of an intra-membrane super-complex dominated by the ATP-synthase, photosystem I (PSI) reaction-center complex and the ferredoxin-NADP+ Reductase (FNR) in the thylakoid membrane. The presence of the super-complex has been documented by mass spectrometry, clear-native PAGE and Western Blot analyses. This is the first documented presence of ATP synthase in a super-complex with the PSI reaction-center located in the non-appressed stromal domain of the thylakoid membrane.


Assuntos
Cloroplastos/metabolismo , Ferredoxina-NADP Redutase/metabolismo , Óxido Nítrico Sintase/metabolismo , Complexo de Proteína do Fotossistema I/metabolismo , Complexo de Proteína do Fotossistema II/metabolismo , ATPases Translocadoras de Prótons/metabolismo , Tilacoides/metabolismo , Trifosfato de Adenosina/metabolismo , Transporte de Elétrons , Fotossíntese , Folhas de Planta/metabolismo , Proteínas de Plantas/metabolismo , Spinacia oleracea/crescimento & desenvolvimento , Spinacia oleracea/metabolismo
4.
Nat Commun ; 11(1): 3906, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764563

RESUMO

Enzymatic hydroxylation of unactivated primary carbons is generally associated with the use of molecular oxygen as co-substrate for monooxygenases. However, in anaerobic cholesterol-degrading bacteria such as Sterolibacterium denitrificans the primary carbon of the isoprenoid side chain is oxidised to a carboxylate in the absence of oxygen. Here, we identify an enzymatic reaction sequence comprising two molybdenum-dependent hydroxylases and one ATP-dependent dehydratase that accomplish the hydroxylation of unactivated primary C26 methyl group of cholesterol with water: (i) hydroxylation of C25 to a tertiary alcohol, (ii) ATP-dependent dehydration to an alkene via a phosphorylated intermediate, (iii) hydroxylation of C26 to an allylic alcohol that is subsequently oxidised to the carboxylate. The three-step enzymatic reaction cascade divides the high activation energy barrier of primary C-H bond cleavage into three biologically feasible steps. This finding expands our knowledge of biological C-H activations beyond canonical oxygenase-dependent reactions.


Assuntos
Trifosfato de Adenosina/metabolismo , Betaproteobacteria/metabolismo , Anaerobiose , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Betaproteobacteria/genética , Carbono/química , Colestadienóis/química , Colestadienóis/metabolismo , Colesterol/química , Colesterol/metabolismo , Genes Bacterianos , Hidroliases/genética , Hidroliases/metabolismo , Hidroxilação , Oxigenases de Função Mista/genética , Oxigenases de Função Mista/metabolismo , Modelos Biológicos , Oxirredução , Filogenia , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Água/metabolismo
5.
Nat Commun ; 11(1): 4263, 2020 08 26.
Artigo em Inglês | MEDLINE | ID: mdl-32848132

RESUMO

Eukaryotic DNA replication initiation relies on the origin recognition complex (ORC), a DNA-binding ATPase that loads the Mcm2-7 replicative helicase onto replication origins. Here, we report cryo-electron microscopy (cryo-EM) structures of DNA-bound Drosophila ORC with and without the co-loader Cdc6. These structures reveal that Orc1 and Orc4 constitute the primary DNA binding site in the ORC ring and cooperate with the winged-helix domains to stabilize DNA bending. A loop region near the catalytic Walker B motif of Orc1 directly contacts DNA, allosterically coupling DNA binding to ORC's ATPase site. Correlating structural and biochemical data show that DNA sequence modulates DNA binding and remodeling by ORC, and that DNA bending promotes Mcm2-7 loading in vitro. Together, these findings explain the distinct DNA sequence-dependencies of metazoan and S. cerevisiae initiators in origin recognition and support a model in which DNA geometry and bendability contribute to Mcm2-7 loading site selection in metazoans.


Assuntos
Proteínas de Ciclo Celular/química , Proteínas de Ciclo Celular/metabolismo , Proteínas de Drosophila/química , Proteínas de Drosophila/metabolismo , Complexo de Reconhecimento de Origem/química , Complexo de Reconhecimento de Origem/metabolismo , Origem de Replicação , Domínio AAA , Trifosfato de Adenosina/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Microscopia Crioeletrônica , DNA/química , DNA/metabolismo , Proteínas de Drosophila/genética , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Hidrólise , Proteínas de Manutenção de Minicromossomo/química , Proteínas de Manutenção de Minicromossomo/genética , Proteínas de Manutenção de Minicromossomo/metabolismo , Modelos Moleculares , Complexo de Reconhecimento de Origem/genética , Ligação Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Origem de Replicação/genética , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
6.
PLoS One ; 15(8): e0232917, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32810161

RESUMO

In human lung cancer progression, the EMT process is characterized by the transformation of cancer cells into invasive forms that migrate to other organs. Targeting to EMT-related molecules is emerging as a novel therapeutic approach for the prevention of lung cancer cell migration and invasion. Traf2- and Nck-interacting kinase (TNIK) has recently been considered as an anti-proliferative target molecule to regulate the Wnt signaling pathway in several types of cancer cells. In the present study, we evaluated the inhibitory effect of a tyrosine kinase inhibitor sunitinib and the integrin-αⅤß3 targeted cyclic peptide (cRGDfK) on EMT in human lung cancer cells. Sunitinib strongly inhibited the TGF-ß1-activated EMT through suppression of Wnt signaling, Smad and non-Smad signaling pathways. In addition, the cRGDfK also inhibited the expression of TGFß1-induced mesenchymal marker genes and proteins. The anti-EMT effect of sunitinib was enhanced when cRGDfK was treated together. When sunitinib was treated with cRGDfK, the mRNA and protein expression levels of mesenchymal markers were decreased compared to the treatment with sunitinib alone. Co-treatment of cRGDfK has shown the potential to improve the efficacy of anticancer agents in combination with therapeutic agents that may be toxic at high concentrations. These results provide new and improved therapies for treating and preventing EMT-related disorders, such as lung fibrosis and cancer metastasis, and relapse.


Assuntos
Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Transição Epitelial-Mesenquimal/efeitos dos fármacos , Neoplasias Pulmonares/tratamento farmacológico , Peptídeos Cíclicos/administração & dosagem , Sunitinibe/administração & dosagem , Fator de Crescimento Transformador beta1/antagonistas & inibidores , Células A549 , Trifosfato de Adenosina/metabolismo , Protocolos de Quimioterapia Combinada Antineoplásica/administração & dosagem , Biomarcadores Tumorais/genética , Biomarcadores Tumorais/metabolismo , Carcinoma Pulmonar de Células não Pequenas/metabolismo , Carcinoma Pulmonar de Células não Pequenas/patologia , Domínio Catalítico , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Sinergismo Farmacológico , Transição Epitelial-Mesenquimal/genética , Transição Epitelial-Mesenquimal/fisiologia , Humanos , Integrina alfaVbeta3/antagonistas & inibidores , Neoplasias Pulmonares/metabolismo , Neoplasias Pulmonares/patologia , Simulação de Acoplamento Molecular , Invasividade Neoplásica/patologia , Invasividade Neoplásica/prevenção & controle , Proteínas Serina-Treonina Quinases/antagonistas & inibidores , Proteínas Serina-Treonina Quinases/química , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Smad/metabolismo , Via de Sinalização Wnt/efeitos dos fármacos
7.
Nat Commun ; 11(1): 3921, 2020 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-32764564

RESUMO

The vacuolar-type H+-ATPases (V-ATPase) hydrolyze ATP to pump protons across the plasma or intracellular membrane, secreting acids to the lumen or acidifying intracellular compartments. It has been implicated in tumor metastasis, renal tubular acidosis, and osteoporosis. Here, we report two cryo-EM structures of the intact V-ATPase from bovine brain with all the subunits including the subunit H, which is essential for ATPase activity. Two type-I transmembrane proteins, Ac45 and (pro)renin receptor, along with subunit c", constitute the core of the c-ring. Three different conformations of A/B heterodimers suggest a mechanism for ATP hydrolysis that triggers a rotation of subunits DF, inducing spinning of subunit d with respect to the entire c-ring. Moreover, many lipid molecules have been observed in the Vo domain to mediate the interactions between subunit c, c", (pro)renin receptor, and Ac45. These two structures reveal unique features of mammalian V-ATPase and suggest a mechanism of V1-Vo torque transmission.


Assuntos
Encéfalo/enzimologia , ATPases Vacuolares Próton-Translocadoras/química , Trifosfato de Adenosina/metabolismo , Animais , Bovinos , Microscopia Crioeletrônica , Hidrólise , Modelos Moleculares , Domínios e Motivos de Interação entre Proteínas , Multimerização Proteica , Estrutura Quaternária de Proteína , Subunidades Proteicas , Prótons , ATPases Vacuolares Próton-Translocadoras/metabolismo , ATPases Vacuolares Próton-Translocadoras/ultraestrutura
8.
Nat Commun ; 11(1): 4319, 2020 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-32859923

RESUMO

Disrupted energy metabolism drives cell dysfunction and disease, but approaches to increase or preserve ATP are lacking. To generate a comprehensive metabolic map of genes and pathways that regulate cellular ATP-the ATPome-we conducted a genome-wide CRISPR interference/activation screen integrated with an ATP biosensor. We show that ATP level is modulated by distinct mechanisms that promote energy production or inhibit consumption. In our system HK2 is the greatest ATP consumer, indicating energy failure may not be a general deficiency in producing ATP, but rather failure to recoup the ATP cost of glycolysis and diversion of glucose metabolites to the pentose phosphate pathway. We identify systems-level reciprocal inhibition between the HIF1 pathway and mitochondria; glycolysis-promoting enzymes inhibit respiration even when there is no glycolytic ATP production, and vice versa. Consequently, suppressing alternative metabolism modes paradoxically increases energy levels under substrate restriction. This work reveals mechanisms of metabolic control, and identifies therapeutic targets to correct energy failure.


Assuntos
Trifosfato de Adenosina/metabolismo , Redes e Vias Metabólicas/genética , Redes e Vias Metabólicas/fisiologia , Trifosfato de Adenosina/genética , Sistemas CRISPR-Cas , Linhagem Celular , Metabolismo Energético , Feminino , Fibroblastos , Regulação da Expressão Gênica , Técnicas de Silenciamento de Genes , Glucose/metabolismo , Glicólise/fisiologia , Hexoquinase/genética , Hexoquinase/metabolismo , Humanos , Células K562 , Metabolômica , Mitocôndrias/metabolismo , Via de Pentose Fosfato , Mutação Puntual
9.
Nucleic Acids Res ; 48(14): 7991-8005, 2020 08 20.
Artigo em Inglês | MEDLINE | ID: mdl-32621607

RESUMO

DNA2 is an essential enzyme involved in DNA replication and repair in eukaryotes. In a search for homologues of this protein, we identified and characterised Geobacillus stearothermophilus Bad, a bacterial DNA helicase-nuclease with similarity to human DNA2. We show that Bad contains an Fe-S cluster and identify four cysteine residues that are likely to co-ordinate the cluster by analogy to DNA2. The purified enzyme specifically recognises ss-dsDNA junctions and possesses ssDNA-dependent ATPase, ssDNA binding, ssDNA endonuclease, 5' to 3' ssDNA translocase and 5' to 3' helicase activity. Single molecule analysis reveals that Bad is a processive DNA motor capable of moving along DNA for distances of >4 kb at a rate of ∼200 bp per second at room temperature. Interestingly, as reported for the homologous human and yeast DNA2 proteins, the DNA unwinding activity of Bad is cryptic and can be unmasked by inactivating the intrinsic nuclease activity. Strikingly, our experiments show that the enzyme loops DNA while translocating, which is an emerging feature of processive DNA unwinding enzymes. The bacterial Bad enzymes will provide an excellent model system for understanding the biochemical properties of DNA2-like helicase-nucleases and DNA looping motor proteins in general.


Assuntos
Proteínas de Bactérias/metabolismo , DNA Helicases/metabolismo , DNA de Cadeia Simples/metabolismo , Desoxirribonuclease I/metabolismo , Geobacillus stearothermophilus/enzimologia , Adenosina Trifosfatases/química , Adenosina Trifosfatases/isolamento & purificação , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/isolamento & purificação , DNA , DNA Helicases/química , DNA Helicases/isolamento & purificação , Desoxirribonuclease I/química , Desoxirribonuclease I/isolamento & purificação
10.
Proc Natl Acad Sci U S A ; 117(31): 18459-18469, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32694211

RESUMO

Mdn1 is an essential mechanoenzyme that uses the energy from ATP hydrolysis to physically reshape and remodel, and thus mature, the 60S subunit of the ribosome. This massive (>500 kDa) protein has an N-terminal AAA (ATPase associated with diverse cellular activities) ring, which, like dynein, has six ATPase sites. The AAA ring is followed by large (>2,000 aa) linking domains that include an ∼500-aa disordered (D/E-rich) region, and a C-terminal substrate-binding MIDAS domain. Recent models suggest that intramolecular docking of the MIDAS domain onto the AAA ring is required for Mdn1 to transmit force to its ribosomal substrates, but it is not currently understood what role the linking domains play, or why tethering the MIDAS domain to the AAA ring is required for protein function. Here, we use chemical probes, single-particle electron microscopy, and native mass spectrometry to study the AAA and MIDAS domains separately or in combination. We find that Mdn1 lacking the D/E-rich and MIDAS domains retains ATP and chemical probe binding activities. Free MIDAS domain can bind to the AAA ring of this construct in a stereo-specific bimolecular interaction, and, interestingly, this binding reduces ATPase activity. Whereas intramolecular MIDAS docking appears to require a treatment with a chemical inhibitor or preribosome binding, bimolecular MIDAS docking does not. Hence, tethering the MIDAS domain to the AAA ring serves to prevent, rather than promote, MIDAS docking in the absence of inducing signals.


Assuntos
ATPases Associadas a Diversas Atividades Celulares/química , ATPases Associadas a Diversas Atividades Celulares/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/enzimologia , ATPases Associadas a Diversas Atividades Celulares/genética , Trifosfato de Adenosina/metabolismo , Regulação Alostérica , Sítios de Ligação , Domínios Proteicos , Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética
11.
Transplantation ; 104(9): 1825-1831, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32675744

RESUMO

BACKGROUND: The lack of organs for kidney transplantation is a growing concern. Expansion in organ supply has been proposed through the use of organs after circulatory death (donation after circulatory death [DCD]). However, many DCD grafts are discarded because of long warm ischemia times, and the absence of reliable measure of kidney viability. P magnetic resonance imaging (pMRI) spectroscopy is a noninvasive method to detect high-energy phosphate metabolites, such as ATP. Thus, pMRI could predict kidney energy state, and its viability before transplantation. METHODS: To mimic DCD, pig kidneys underwent 0, 30, or 60 min of warm ischemia, before hypothermic machine perfusion. During the ex vivo perfusion, we assessed energy metabolites using pMRI. In addition, we performed Gadolinium perfusion sequences. Each sample underwent histopathological analyzing and scoring. Energy status and kidney perfusion were correlated with kidney injury. RESULTS: Using pMRI, we found that in pig kidney, ATP was rapidly generated in presence of oxygen (100 kPa), which remained stable up to 22 h. Warm ischemia (30 and 60 min) induced significant histological damages, delayed cortical and medullary Gadolinium elimination (perfusion), and reduced ATP levels, but not its precursors (AMP). Finally, ATP levels and kidney perfusion both inversely correlated with the severity of kidney histological injury. CONCLUSIONS: ATP levels, and kidney perfusion measurements using pMRI, are biomarkers of kidney injury after warm ischemia. Future work will define the role of pMRI in predicting kidney graft and patient's survival.


Assuntos
Trifosfato de Adenosina/metabolismo , Transplante de Rim , Rim/metabolismo , Espectroscopia de Ressonância Magnética/métodos , Animais , Feminino , Perfusão , Suínos
12.
Am J Physiol Renal Physiol ; 319(2): F292-F303, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32686520

RESUMO

In proteinuric renal diseases, excessive plasma nonesterified free fatty acids bound to albumin can leak across damaged glomeruli to be reabsorbed by renal proximal tubular cells and cause inflammatory tubular cells damage by as yet unknown mechanisms. The present study was designed to investigate these mechanisms induced by palmitic acid (PA; one of the nonesterified free fatty acids) overload. Our results show that excess PA stimulates ATP release through the pannexin 1 channel in human renal tubule epithelial cells (HK-2), increasing extracellular ATP concentration approximately threefold compared with control. The ATP release is dependent on caspase-3/7 activation induced by mitochondrial reactive oxygen species. Furthermore, extracellular ATP aggravates PA-induced monocyte chemoattractant protein-1 secretion and monocyte infiltration of tubular cells, enlarging the inflammatory response in both macrophages and HK-2 cells via the purinergic P2X7 receptor-mammalian target of rapamycin-forkhead box O1-thioredoxin-interacting protein/NOD-like receptor protein 3 inflammasome pathway. Hence, PA increases mitochondrial reactive oxygen species-induced ATP release and inflammatory stress, which cause a "first hit," while ATP itself is a "second hit" in amplifying the renal tubular inflammatory response. Thus, inhibition of ATP release or the purinergic P2X7 receptor may be an approach to reduce renal inflammation and improve renal function.


Assuntos
Trifosfato de Adenosina/metabolismo , Ácidos Graxos não Esterificados/metabolismo , Inflamassomos/metabolismo , Túbulos Renais/metabolismo , Células Epiteliais/metabolismo , Humanos , Macrófagos/metabolismo , Monócitos/metabolismo , Espécies Reativas de Oxigênio/metabolismo
13.
Nat Commun ; 11(1): 3653, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32694534

RESUMO

The vasculature represents a highly plastic compartment, capable of switching from a quiescent to an active proliferative state during angiogenesis. Metabolic reprogramming in endothelial cells (ECs) thereby is crucial to cover the increasing cellular energy demand under growth conditions. Here we assess the impact of mitochondrial bioenergetics on neovascularisation, by deleting cox10 gene encoding an assembly factor of cytochrome c oxidase (COX) specifically in mouse ECs, providing a model for vasculature-restricted respiratory deficiency. We show that EC-specific cox10 ablation results in deficient vascular development causing embryonic lethality. In adult mice induction of EC-specific cox10 gene deletion produces no overt phenotype. However, the angiogenic capacity of COX-deficient ECs is severely compromised under energetically demanding conditions, as revealed by significantly delayed wound-healing and impaired tumour growth. We provide genetic evidence for a requirement of mitochondrial respiration in vascular endothelial cells for neoangiogenesis during development, tissue repair and cancer.


Assuntos
Mitocôndrias/metabolismo , Neoplasias/patologia , Neovascularização Patológica/patologia , Neovascularização Fisiológica , Cicatrização/fisiologia , Trifosfato de Adenosina/metabolismo , Alquil e Aril Transferases/genética , Alquil e Aril Transferases/metabolismo , Animais , Linhagem Celular Tumoral/transplante , Respiração Celular , Modelos Animais de Doenças , Embrião de Mamíferos , Desenvolvimento Embrionário/fisiologia , Células Endoteliais/fisiologia , Endotélio Vascular/citologia , Endotélio Vascular/fisiologia , Feminino , Técnicas de Inativação de Genes , Humanos , Masculino , Proteínas de Membrana/genética , Proteínas de Membrana/metabolismo , Camundongos , Camundongos Transgênicos , Mitocôndrias/genética , Neoplasias/irrigação sanguínea , Fosforilação Oxidativa
14.
Nat Commun ; 11(1): 3740, 2020 07 27.
Artigo em Inglês | MEDLINE | ID: mdl-32719356

RESUMO

Mfd couples transcription to nucleotide excision repair, and acts on RNA polymerases when elongation is impeded. Depending on impediment severity, this action results in either transcription termination or elongation rescue, which rely on ATP-dependent Mfd translocation on DNA. Due to its role in antibiotic resistance, Mfd is also emerging as a prime target for developing anti-evolution drugs. Here we report the structure of DNA-bound Mfd, which reveals large DNA-induced structural changes that are linked to the active site via ATPase motif VI. These changes relieve autoinhibitory contacts between the N- and C-termini and unmask UvrA recognition determinants. We also demonstrate that translocation relies on a threonine in motif Ic, widely conserved in translocases, and a family-specific histidine near motif IVa, reminiscent of the "arginine clamp" of RNA helicases. Thus, Mfd employs a mode of DNA recognition that at its core is common to ss/ds translocases that act on DNA or RNA.


Assuntos
Proteínas de Bactérias/metabolismo , Reparo do DNA , DNA/metabolismo , Fatores de Transcrição/metabolismo , Transcrição Genética , Trifosfato de Adenosina/metabolismo , Sequência de Aminoácidos , Proteínas de Bactérias/química , Sítios de Ligação , DNA/química , DNA/ultraestrutura , Escherichia coli/metabolismo , Modelos Moleculares , Ligação Proteica , Domínios Proteicos , RNA Helicases/metabolismo , Fatores de Transcrição/química
15.
Toxicol Lett ; 332: 118-129, 2020 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-32659471

RESUMO

Silver-based antimicrobials are widely used topically to treat infections associated with multi-drug resistant (MDR) pathogens. Expanding this topical use to aerosols to treat lung infections requires understanding and preventing silver toxicity in the respiratory tract. A key mechanism resulting in silver-induced toxicity is the production of reactive oxygen species (ROS). In this study, we have verified ROS generation in silver-treated bronchial epithelial cells prompting evaluation of three antioxidants, N-acetyl cysteine (NAC), ascorbic acid, and melatonin, to identify potential prophylactic agents. Among them, NAC was the only candidate that abrogated the ROS generation in response to silver acetate exposure resulting in the rescue of these cells from silver-associated toxicity. Further, this protective effect directly translated to preservation of metabolic activity, as demonstrated by the normal levels of citric acid cycle metabolites in NAC-pretreated silver acetate-exposed cells. Because the citric acid cycle remained functional, silver-exposed cells pre-incubated with NAC demonstrated significantly higher levels of adenosine triphosphate levels compared with NAC-free controls. Moreover, we found that this prodigious capacity of NAC to rescue silver acetate-exposed cells was due not only to its antioxidant activity, but also to its ability to directly bind silver. Despite binding to silver, NAC did not alter the antimicrobial activity of silver acetate.


Assuntos
Acetilcisteína/farmacologia , Antibacterianos/farmacologia , Depuradores de Radicais Livres/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Prata/farmacologia , Prata/toxicidade , Acetatos/farmacologia , Trifosfato de Adenosina/metabolismo , Ácido Ascórbico/farmacologia , Linhagem Celular , Cromatografia Gasosa-Espectrometria de Massas , Glutationa/metabolismo , Humanos , Melatonina/farmacologia , Testes de Sensibilidade Microbiana , Compostos de Prata/farmacologia , Superóxidos/metabolismo
16.
PLoS One ; 15(7): e0235515, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32692781

RESUMO

BACKGROUND: The skin provides a predominant barrier against chemical, physical and microbial incursion. The intemperate exposure to ultraviolet A (UVA) radiation can cause excessive cellular oxidative stress, leading to skin damage, proteins damage and mitochondrial dysfunction. There is sufficient evidences supporting the proposal that mitochondria is highly implicated in skin photo-damage. METHODS: In the present study, a polysaccharide isolated from Astragalus membranaceus was further purified to be an α-glucan, which was further investigated its beneficial influence on UVA-induced photo-damage in HaCaT cells. RESULTS: Our results showed that the purified Astragalus membranaceus polysaccharide (AP) can protect HaCaT cells from UVA-induced photo-damage through reducing UVA-induced intracellular ROS production and mitochondrial membrane potential, thereby altering ATP content. It was found that the UVA induced damage in HaCaT cells could be effectively restored by co-treatment with AP. CONCLUSIONS: AP exhibited promising potential for advanced application as multifunctional skin care products and drugs.


Assuntos
Astragalus propinquus/química , Queratinócitos/efeitos dos fármacos , Queratinócitos/efeitos da radiação , Polissacarídeos/farmacologia , Protetores contra Radiação/farmacologia , Raios Ultravioleta/efeitos adversos , Trifosfato de Adenosina/metabolismo , Apoptose/efeitos dos fármacos , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Humanos , Queratinócitos/citologia , Queratinócitos/metabolismo , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Polissacarídeos/química , Protetores contra Radiação/química , Espécies Reativas de Oxigênio/metabolismo
17.
Proc Natl Acad Sci U S A ; 117(32): 19599-19603, 2020 08 11.
Artigo em Inglês | MEDLINE | ID: mdl-32719136

RESUMO

We have used recent measurements of mammalian cone light responses and voltage-gated currents to calculate cone ATP utilization and compare it to that of rods. The largest expenditure of ATP results from ion transport, particularly from removal of Na+ entering outer segment light-dependent channels and inner segment hyperpolarization-activated cyclic nucleotide-gated channels, and from ATP-dependent pumping of Ca2+ entering voltage-gated channels at the synaptic terminal. Single cones expend nearly twice as much energy as single rods in darkness, largely because they make more synapses with second-order retinal cells and thus must extrude more Ca2+ In daylight, cone ATP utilization per cell remains high because cones never remain saturated and must continue to export Na+ and synaptic Ca2+ even in bright illumination. In mouse and human retina, rods greatly outnumber cones and consume more energy overall even in background light. In primates, however, the high density of cones in the fovea produces a pronounced peak of ATP utilization, which becomes particularly prominent in daylight and may make this part of the retina especially sensitive to changes in energy availability.


Assuntos
Retina/metabolismo , Células Fotorreceptoras Retinianas Cones/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Cálcio/metabolismo , GMP Cíclico/metabolismo , Canais de Cátion Regulados por Nucleotídeos Cíclicos/metabolismo , Fóvea Central/citologia , Fóvea Central/metabolismo , Humanos , Canais Disparados por Nucleotídeos Cíclicos Ativados por Hiperpolarização/metabolismo , Ativação do Canal Iônico , Luz , Camundongos , Terminações Pré-Sinápticas/metabolismo , Retina/citologia , Células Fotorreceptoras Retinianas Bastonetes/metabolismo , Sódio/metabolismo
18.
Proc Natl Acad Sci U S A ; 117(30): 17775-17784, 2020 07 28.
Artigo em Inglês | MEDLINE | ID: mdl-32669440

RESUMO

DNA mismatch repair (MMR), the guardian of the genome, commences when MutS identifies a mismatch and recruits MutL to nick the error-containing strand, allowing excision and DNA resynthesis. Dominant MMR models posit that after mismatch recognition, ATP converts MutS to a hydrolysis-independent, diffusive mobile clamp that no longer recognizes the mismatch. Little is known about the postrecognition MutS mobile clamp and its interactions with MutL. Two disparate frameworks have been proposed: One in which MutS-MutL complexes remain mobile on the DNA, and one in which MutL stops MutS movement. Here we use single-molecule FRET to follow the postrecognition states of MutS and the impact of MutL on its properties. In contrast to current thinking, we find that after the initial mobile clamp formation event, MutS undergoes frequent cycles of mismatch rebinding and mobile clamp reformation without releasing DNA. Notably, ATP hydrolysis is required to alter the conformation of MutS such that it can recognize the mismatch again instead of bypassing it; thus, ATP hydrolysis licenses the MutS mobile clamp to rebind the mismatch. Moreover, interaction with MutL can both trap MutS at the mismatch en route to mobile clamp formation and stop movement of the mobile clamp on DNA. MutS's frequent rebinding of the mismatch, which increases its residence time in the vicinity of the mismatch, coupled with MutL's ability to trap MutS, should increase the probability that MutS-MutL MMR initiation complexes localize near the mismatch.


Assuntos
Reparo de Erro de Pareamento de DNA , DNA/metabolismo , Proteína MutS de Ligação de DNA com Erro de Pareamento/metabolismo , Adenosina Trifosfatases/metabolismo , Trifosfato de Adenosina/metabolismo , Pareamento Incorreto de Bases , DNA/química , DNA/genética , Hidrólise , Modelos Moleculares , Complexos Multiproteicos/metabolismo , Proteínas MutL/química , Proteínas MutL/metabolismo , Proteína MutS de Ligação de DNA com Erro de Pareamento/química , Relação Estrutura-Atividade
19.
Proc Natl Acad Sci U S A ; 117(31): 18448-18458, 2020 08 04.
Artigo em Inglês | MEDLINE | ID: mdl-32675243

RESUMO

Under physiological conditions, most Ca2+-ATPase (SERCA) molecules bind ATP before binding the Ca2+ transported. SERCA has a high affinity for ATP even in the absence of Ca2+, and ATP accelerates Ca2+ binding at pH values lower than 7, where SERCA is in the E2 state with low-affinity Ca2+-binding sites. Here we describe the crystal structure of SERCA2a, the isoform predominant in cardiac muscle, in the E2·ATP state at 3.0-Å resolution. In the crystal structure, the arrangement of the cytoplasmic domains is distinctly different from that in canonical E2. The A-domain now takes an E1 position, and the N-domain occupies exactly the same position as that in the E1·ATP·2Ca2+ state relative to the P-domain. As a result, ATP is properly delivered to the phosphorylation site. Yet phosphoryl transfer never takes place without the filling of the two transmembrane Ca2+-binding sites. The present crystal structure explains what ATP binding itself does to SERCA and how nonproductive phosphorylation is prevented in E2.


Assuntos
Trifosfato de Adenosina/metabolismo , Cálcio/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Cristalografia por Raios X , Humanos , Miocárdio/metabolismo , Fosforilação , Conformação Proteica , Domínios Proteicos , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética
20.
Nat Commun ; 11(1): 3479, 2020 07 13.
Artigo em Inglês | MEDLINE | ID: mdl-32661250

RESUMO

Genetic factors contribute to the risk of thrombotic diseases. Recent genome wide association studies have identified genetic loci including SLC44A2 which may regulate thrombosis. Here we show that Slc44a2 controls platelet activation and thrombosis by regulating mitochondrial energetics. We find that Slc44a2 null mice (Slc44a2(KO)) have increased bleeding times and delayed thrombosis compared to wild-type (Slc44a2(WT)) controls. Platelets from Slc44a2(KO) mice have impaired activation in response to thrombin. We discover that Slc44a2 mediates choline transport into mitochondria, where choline metabolism leads to an increase in mitochondrial oxygen consumption and ATP production. Platelets lacking Slc44a2 contain less ATP at rest, release less ATP when activated, and have an activation defect that can be rescued by exogenous ADP. Taken together, our data suggest that mitochondria require choline for maximum function, demonstrate the importance of mitochondrial metabolism to platelet activation, and reveal a mechanism by which Slc44a2 influences thrombosis.


Assuntos
Proteínas de Membrana Transportadoras/metabolismo , Mitocôndrias/metabolismo , Ativação Plaquetária/fisiologia , Trombose/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Western Blotting , Modelos Animais de Doenças , Estudo de Associação Genômica Ampla , Masculino , Espectrometria de Massas , Proteínas de Membrana Transportadoras/genética , Camundongos , Camundongos Knockout , Mitocôndrias/genética , Ativação Plaquetária/genética , Agregação Plaquetária/genética , Agregação Plaquetária/fisiologia , Reação em Cadeia da Polimerase em Tempo Real , Trombose/genética
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