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1.
Nat Commun ; 11(1): 4916, 2020 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-33004803

RESUMO

Self-incompatibility (SI) is a breeding system that promotes cross-fertilization. In Brassica, pollen rejection is induced by a haplotype-specific interaction between pistil determinant SRK (S receptor kinase) and pollen determinant SP11 (S-locus Protein 11, also named SCR) from the S-locus. Although the structure of the B. rapa S9-SRK ectodomain (eSRK) and S9-SP11 complex has been determined, it remains unclear how SRK discriminates self- and nonself-SP11. Here, we uncover the detailed mechanism of self/nonself-discrimination in Brassica SI by determining the S8-eSRK-S8-SP11 crystal structure and performing molecular dynamics (MD) simulations. Comprehensive binding analysis of eSRK and SP11 structures reveals that the binding free energies are most stable for cognate eSRK-SP11 combinations. Residue-based contribution analysis suggests that the modes of eSRK-SP11 interactions differ between intra- and inter-subgroup (a group of phylogenetically neighboring haplotypes) combinations. Our data establish a model of self/nonself-discrimination in Brassica SI.


Assuntos
Brassica rapa/fisiologia , Melhoramento Vegetal , Proteínas de Plantas/metabolismo , Proteínas Quinases/metabolismo , Animais , Cristalografia , Flores/metabolismo , Haplótipos , Simulação de Dinâmica Molecular , Proteínas de Plantas/genética , Proteínas de Plantas/ultraestrutura , Pólen/metabolismo , Ligação Proteica/fisiologia , Domínios Proteicos/fisiologia , Proteínas Quinases/genética , Proteínas Quinases/ultraestrutura , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/ultraestrutura , Células Sf9 , Spodoptera
2.
Opt Lett ; 45(19): 5428-5431, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-33001920

RESUMO

We show that waveguide sensors can enable a quantitative characterization of coronavirus spike glycoprotein-host-receptor binding-the process whereby coronaviruses enter human cells, causing disease. We demonstrate that such sensors can help quantify and eventually understand kinetic and thermodynamic properties of viruses that control their affinity to targeted cells, which is known to significantly vary in the course of virus evolution, e.g., from SARS-CoV to SARS-CoV-2, making the development of virus-specific drugs and vaccine difficult. With the binding rate constants and thermodynamic parameters as suggested by the latest SARS-CoV-2 research, optical sensors of SARS-CoV-2 spike protein-receptor binding may be within sight.


Assuntos
Betacoronavirus , Técnicas Biossensoriais , Infecções por Coronavirus , Óptica e Fotônica/instrumentação , Pandemias , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral , Receptores Virais/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo , Sítios de Ligação , Humanos , Ligação Proteica/fisiologia
3.
Haematologica ; Online ahead of print2020 09 10.
Artigo em Inglês | MEDLINE | ID: mdl-33054129

RESUMO

SARS-CoV-2 disease (COVID-19) has affected over 22 million patients worldwide as of August 2020. As the medical community seeks better understanding of the underlying pathophysiology of COVID-19, several theories have been proposed. One widely shared theory suggests that SARS-CoV-2 proteins directly interact with human hemoglobin (Hb) and facilitate removal of iron from the heme prosthetic group, leading to the loss of functional hemoglobin and accumulation of iron. Herein, we refute this theory. We compared clinical data from 21 critically ill COVID-19 patients to 21 non-COVID-19 ARDS patient controls, generating hemoglobin-oxygen dissociation curves from venous blood gases. This curve generated from the COVID-19 cohort matched the idealized oxygen-hemoglobin dissociation curve well (Pearson correlation, R2 = 0.97, P.


Assuntos
Betacoronavirus , Infecções por Coronavirus/sangue , Infecções por Coronavirus/diagnóstico , Hemoglobinas/metabolismo , Pneumonia Viral/sangue , Pneumonia Viral/diagnóstico , Adulto , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Pandemias , Ligação Proteica/fisiologia
4.
PLoS Comput Biol ; 16(9): e1008103, 2020 09.
Artigo em Inglês | MEDLINE | ID: mdl-32956350

RESUMO

Highly coordinated water molecules are frequently an integral part of protein-protein and protein-ligand interfaces. We introduce an updated energy model that efficiently captures the energetic effects of these ordered water molecules on the surfaces of proteins. A two-stage method is developed in which polar groups arranged in geometries suitable for water placement are first identified, then a modified Monte Carlo simulation allows highly coordinated waters to be placed on the surface of a protein while simultaneously sampling amino acid side chain orientations. This "semi-explicit" water model is implemented in Rosetta and is suitable for both structure prediction and protein design. We show that our new approach and energy model yield significant improvements in native structure recovery of protein-protein and protein-ligand docking discrimination tests.


Assuntos
Sítios de Ligação/fisiologia , Simulação de Acoplamento Molecular , Ligação Proteica/fisiologia , Proteínas , Água , Algoritmos , Aminoácidos/química , Aminoácidos/metabolismo , Ligação de Hidrogênio , Ligantes , Método de Monte Carlo , Proteínas/química , Proteínas/metabolismo , Água/química , Água/metabolismo
5.
PLoS One ; 15(9): e0225293, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32991576

RESUMO

Grain hardness is an important quality trait of cereal crops. In wheat, it is mainly determined by the Hardness locus that harbors genes encoding puroindoline A (PINA) and puroindoline B (PINB). Any deletion or mutation of these genes leading to the absence of PINA or to single amino acid changes in PINB leads to hard endosperms. Although it is generally acknowledged that hardness is controlled by adhesion strength between the protein matrix and starch granules, the physicochemical mechanisms connecting puroindolines and the starch-protein interactions are unknown as of this time. To explore these mechanisms, we focused on PINA. The overexpression in a hard wheat cultivar (cv. Courtot with the Pina-D1a and Pinb-D1d alleles) decreased grain hardness in a dose-related effect, suggesting an interactive process. When PINA was added to gliadins in solution, large aggregates of up to 13 µm in diameter were formed. Turbidimetry measurements showed that the PINA-gliadin interaction displayed a high cooperativity that increased with a decrease in pH from neutral to acid (pH 4) media, mimicking the pH change during endosperm development. No turbidity was observed in the presence of isolated α- and γ-gliadins, but non-cooperative interactions of PINA with these proteins could be confirmed by surface plasmon resonance. A significant higher interaction of PINA with γ-gliadins than with α-gliadins was observed. Similar binding behavior was observed with a recombinant repeated polypeptide that mimics the repeat domain of gliadins, i.e., (Pro-Gln-Gln-Pro-Tyr)8. Taken together, these results suggest that the interaction of PINA with a monomeric gliadin creates a nucleation point leading to the aggregation of other gliadins, a phenomenon that could prevent further interaction of the storage prolamins with starch granules. Consequently, the role of puroindoline-prolamin interactions on grain hardness should be addressed on the basis of previous observations that highlight the similar subcellular routing of storage prolamins and puroindolines.


Assuntos
Grão Comestível/metabolismo , Gliadina/metabolismo , Dureza/fisiologia , Proteínas de Plantas/metabolismo , Triticum/metabolismo , Produção Agrícola , Difusão Dinâmica da Luz , Grão Comestível/química , Gliadina/química , Concentração de Íons de Hidrogênio , Nefelometria e Turbidimetria , Tamanho da Partícula , Proteínas de Plantas/química , Agregados Proteicos/fisiologia , Ligação Proteica/fisiologia , Domínios Proteicos/fisiologia , Sequências Repetitivas de Aminoácidos/fisiologia , Amido/química , Amido/metabolismo , Ressonância de Plasmônio de Superfície , Triticum/química
6.
Proc Natl Acad Sci U S A ; 117(37): 22815-22822, 2020 09 15.
Artigo em Inglês | MEDLINE | ID: mdl-32868420

RESUMO

The sensitive and accurate quantification of protein biomarkers plays important roles in clinical diagnostics and biomedical research. Sandwich ELISA and its variants accomplish the capture and detection of a target protein via two antibodies that tightly bind at least two distinct epitopes of the same antigen and have been the gold standard for sensitive protein quantitation for decades. However, existing antibody-based assays cannot distinguish between signal arising from specific binding to the protein of interest and nonspecific binding to assay surfaces or matrix components, resulting in significant background signal even in the absence of the analyte. As a result, they generally do not achieve single-molecule sensitivity, and they require two high-affinity antibodies as well as stringent washing to maximize sensitivity and reproducibility. Here, we show that surface capture with a high-affinity antibody combined with kinetic fingerprinting using a dynamically binding, low-affinity fluorescent antibody fragment differentiates between specific and nonspecific binding at the single-molecule level, permitting the direct, digital counting of single protein molecules with femtomolar-to-attomolar limits of detection (LODs). We apply this approach to four exemplary antigens spiked into serum, demonstrating LODs 55- to 383-fold lower than commercially available ELISA. As a real-world application, we establish that endogenous interleukin-6 (IL-6) can be quantified in 2-µL serum samples from chimeric antigen receptor T cell (CAR-T cell) therapy patients without washing away excess serum or detection probes, as is required in ELISA-based approaches. This kinetic fingerprinting thus exhibits great potential for the ultrasensitive, rapid, and streamlined detection of many clinically relevant proteins.


Assuntos
Ligação Proteica/fisiologia , Imagem Individual de Molécula/métodos , Anticorpos/imunologia , Especificidade de Anticorpos/imunologia , Especificidade de Anticorpos/fisiologia , Biomarcadores/sangue , Ensaio de Imunoadsorção Enzimática/métodos , Humanos , Cinética , Limite de Detecção , Nanotecnologia , Proteínas , Reprodutibilidade dos Testes
7.
Proc Natl Acad Sci U S A ; 117(35): 21740-21746, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817533

RESUMO

The Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) anion channel is essential for epithelial salt-water balance. CFTR mutations cause cystic fibrosis, a lethal incurable disease. In cells CFTR is activated through the cAMP signaling pathway, overstimulation of which during cholera leads to CFTR-mediated intestinal salt-water loss. Channel activation is achieved by phosphorylation of its regulatory (R) domain by cAMP-dependent protein kinase catalytic subunit (PKA). Here we show using two independent approaches--an ATP analog that can drive CFTR channel gating but is unsuitable for phosphotransfer by PKA, and CFTR mutants lacking phosphorylatable serines--that PKA efficiently opens CFTR channels through simple binding, under conditions that preclude phosphorylation. Unlike when phosphorylation happens, CFTR activation by PKA binding is completely reversible. Thus, PKA binding promotes release of the unphosphorylated R domain from its inhibitory position, causing full channel activation, whereas phosphorylation serves only to maintain channel activity beyond termination of the PKA signal. The results suggest two levels of CFTR regulation in cells: irreversible through phosphorylation, and reversible through R-domain binding to PKA--and possibly also to other members of a large network of proteins known to interact with the channel.


Assuntos
Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Regulador de Condutância Transmembrana em Fibrose Cística/metabolismo , Canais de Ânion Dependentes de Voltagem/metabolismo , Trifosfato de Adenosina/metabolismo , Animais , Ânions/metabolismo , Fenômenos Biofísicos , Proteínas Quinases Dependentes de AMP Cíclico/fisiologia , Regulador de Condutância Transmembrana em Fibrose Cística/genética , Regulador de Condutância Transmembrana em Fibrose Cística/fisiologia , Ativação do Canal Iônico/fisiologia , Mutagênese Sítio-Dirigida , Nucleotídeos/metabolismo , Oócitos/metabolismo , Técnicas de Patch-Clamp/métodos , Fosforilação , Ligação Proteica/fisiologia , Serina/metabolismo , Canais de Ânion Dependentes de Voltagem/fisiologia , Proteínas de Xenopus/metabolismo , Xenopus laevis/metabolismo
8.
Proc Natl Acad Sci U S A ; 117(35): 21723-21730, 2020 09 01.
Artigo em Inglês | MEDLINE | ID: mdl-32817560

RESUMO

G proteins are activated when they associate with G protein-coupled receptors (GPCRs), often in response to agonist-mediated receptor activation. It is generally thought that agonist-induced receptor-G protein association necessarily promotes G protein activation and, conversely, that activated GPCRs do not interact with G proteins that they do not activate. Here we show that GPCRs can form agonist-dependent complexes with G proteins that they do not activate. Using cell-based bioluminescence resonance energy transfer (BRET) and luminescence assays we find that vasopressin V2 receptors (V2R) associate with both Gs and G12 heterotrimers when stimulated with the agonist arginine vasopressin (AVP). However, unlike V2R-Gs complexes, V2R-G12 complexes are not destabilized by guanine nucleotides and do not promote G12 activation. Activating V2R does not lead to signaling responses downstream of G12 activation, but instead inhibits basal G12-mediated signaling, presumably by sequestering G12 heterotrimers. Overexpressing G12 inhibits G protein receptor kinase (GRK) and arrestin recruitment to V2R and receptor internalization. Formyl peptide (FPR1 and FPR2) and Smoothened (Smo) receptors also form complexes with G12 that are insensitive to nucleotides, suggesting that unproductive GPCR-G12 complexes are not unique to V2R. These results indicate that agonist-dependent receptor-G protein association does not always lead to G protein activation and may in fact inhibit G protein activation.


Assuntos
Subunidades alfa G12-G13 de Proteínas de Ligação ao GTP/metabolismo , Receptores Acoplados a Proteínas-G/agonistas , Receptores Acoplados a Proteínas-G/metabolismo , Técnicas de Transferência de Energia por Ressonância de Bioluminescência/métodos , AMP Cíclico/metabolismo , Subunidades alfa G12-G13 de Proteínas de Ligação ao GTP/fisiologia , Subunidades alfa Gs de Proteínas de Ligação ao GTP/metabolismo , Subunidades alfa Gs de Proteínas de Ligação ao GTP/fisiologia , Proteínas de Ligação ao GTP/metabolismo , Células HEK293 , Humanos , Ligantes , Ligação Proteica/fisiologia , Receptores de Vasopressinas/metabolismo , Transdução de Sinais/fisiologia , Vasopressinas/metabolismo , beta-Arrestinas/metabolismo
9.
ACS Nano ; 14(8): 10616-10623, 2020 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-32806067

RESUMO

The receptor-binding domain (RBD) of the SARS-CoV-2 spike protein plays a crucial role in binding the human cell receptor ACE2 that is required for viral entry. Many studies have been conducted to target the structures of RBD-ACE2 binding and to design RBD-targeting vaccines and drugs. Nevertheless, mutations distal from the SARS-CoV-2 RBD also impact its transmissibility and antibody can target non-RBD regions, suggesting the incomplete role of the RBD region in the spike protein-ACE2 binding. Here, in order to elucidate distant binding mechanisms, we analyze complexes of ACE2 with the wild-type spike protein and with key mutants via large-scale all-atom explicit solvent molecular dynamics simulations. We find that though distributed approximately 10 nm away from the RBD, the SARS-CoV-2 polybasic cleavage sites enhance, via electrostatic interactions and hydration, the RBD-ACE2 binding affinity. A negatively charged tetrapeptide (GluGluLeuGlu) is then designed to neutralize the positively charged arginine on the polybasic cleavage sites. We find that the tetrapeptide GluGluLeuGlu binds to one of the three polybasic cleavage sites of the SARS-CoV-2 spike protein lessening by 34% the RBD-ACE2 binding strength. This significant binding energy reduction demonstrates the feasibility to neutralize RBD-ACE2 binding by targeting this specific polybasic cleavage site. Our work enhances understanding of the binding mechanism of SARS-CoV-2 to ACE2, which may aid the design of therapeutics for COVID-19 infection.


Assuntos
Betacoronavirus/metabolismo , Infecções por Coronavirus/virologia , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/virologia , Receptores Virais/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo , Substituição de Aminoácidos , Antivirais/química , Antivirais/farmacologia , Betacoronavirus/química , Betacoronavirus/genética , Sítios de Ligação/genética , Desenho de Fármacos , Interações entre Hospedeiro e Microrganismos/efeitos dos fármacos , Humanos , Simulação de Dinâmica Molecular , Mutação , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Pandemias , Peptidil Dipeptidase A/química , Peptidil Dipeptidase A/genética , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/genética , Ligação Proteica/fisiologia , Domínios Proteicos , Receptores Virais/química , Receptores Virais/genética , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Internalização do Vírus
10.
Eur J Pharmacol ; 884: 173455, 2020 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-32745604

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a beta coronavirus that uses the human angiotensin-converting enzyme 2 (ACE2) receptor as a point of entry. The present review discusses the origin and structure of the virus and its mechanism of cell entry followed by the therapeutic potentials of strategies directed towards SARS-CoV2-ACE2 binding, the renin-angiotensin system, and the kinin-kallikrein system. SARS-CoV2-ACE2 binding-directed approaches mainly consist of targeting receptor binding domain, ACE2 blockers, soluble ACE2, and host protease inhibitors. In conclusion, blocking or manipulating the SARS-CoV2-ACE2 binding interface perhaps offers the best tactic against the virus that should be treated as a fundamental subject of future research.


Assuntos
Betacoronavirus/fisiologia , Infecções por Coronavirus , Descoberta de Drogas/métodos , Pandemias , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral , Ligação Proteica , Glicoproteína da Espícula de Coronavírus/metabolismo , Internalização do Vírus/efeitos dos fármacos , Infecções por Coronavirus/tratamento farmacológico , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/virologia , Humanos , Pneumonia Viral/tratamento farmacológico , Pneumonia Viral/metabolismo , Pneumonia Viral/virologia , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Receptores Virais/metabolismo
11.
Life Sci ; 258: 118228, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32781071

RESUMO

AIMS: Cyclin-dependent kinase 9 (CDK9) is a member of the CDK subfamily and plays a major role in the regulation of transcriptional elongation. It has attracted widespread attention as a therapeutic target for cancer. Here, we aimed to explore novel CDK 9 inhibitors by using a hybrid virtual screening strategy. MAIN METHODS: A hybrid virtual screening strategy was constructed with computer-aided drug design (CADD). First, compounds were filtered in accordance with Lipinski's rule of five and adsorption, distribution, metabolism, excretion, and toxicity (ADMET) properties. Second, a 3D-QSAR pharmacophore model was built and used as a 3D query to screen the obtained hit compounds. Third, the hit compounds were subjected to molecular docking studies. Fourth, molecular dynamics (MD) simulations were performed on CDK9 in complex with the final hits to examine the structural stability. Finally, CDK9 kinase biochemical assay was performed to identify the biological activity of the hit compounds. KEY FINDINGS: Seven hit compounds were screened out. These hit compounds showed drug-like properties in accordance with Lipinski's rule of five and ADMET. Complexes involving the six hit compounds bound to CDK9 exhibited good structural stability in the MD simulation. Furthermore, these six hit compounds had strong inhibitory activity against CDK9 kinase. In particular, hit 3 showed the most promising activity with the percentage of 71%. SIGNIFICANCE: The six hit compounds may be promising novel CDK9 inhibitors, and the hybrid virtual screening strategy designed in this study provides an important reference for the design and synthesis of novel CDK9 inhibitors.


Assuntos
Quinase 9 Dependente de Ciclina/antagonistas & inibidores , Quinase 9 Dependente de Ciclina/metabolismo , Simulação de Acoplamento Molecular/métodos , Simulação de Dinâmica Molecular , Inibidores de Proteínas Quinases/metabolismo , Quinase 9 Dependente de Ciclina/química , Avaliação Pré-Clínica de Medicamentos/métodos , Humanos , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Inibidores de Proteínas Quinases/química , Inibidores de Proteínas Quinases/farmacologia , Estrutura Secundária de Proteína
12.
PLoS Comput Biol ; 16(7): e1007789, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32614861

RESUMO

Membrane transport is generally thought to occur via an alternating access mechanism in which the transporter adopts at least two states, accessible from two different sides of the membrane to exchange substrates from the extracellular environment and the cytoplasm or from the cytoplasm and the intracellular matrix of the organelles (only in eukaryotes). In recent years, a number of high resolution structures have supported this general framework for a wide class of transport molecules, although additional states along the transport pathway are emerging as critically important. Given that substrate binding is often weak in order to enhance overall transport rates, there exists the distinct possibility that transporters may transport the incorrect substrate. This is certainly the case for many pharmaceutical compounds that are absorbed in the gut or cross the blood brain barrier through endogenous transporters. Docking studies on the bacterial sugar transporter vSGLT reveal that many highly toxic compounds are compatible with binding to the orthosteric site, further motivating the selective pressure for additional modes of selectivity. Motivated by recent work in which we observed failed substrate delivery in a molecular dynamics simulation where the energized ion still goes down its concentration gradient, we hypothesize that some transporters evolved to harness this 'slip' mechanism to increase substrate selectivity and reduce the uptake of toxic molecules. Here, we test this idea by constructing and exploring a kinetic transport model that includes a slip pathway. While slip reduces the overall productive flux, when coupled with a second toxic molecule that is more prone to slippage, the overall substrate selectivity dramatically increases, suppressing the accumulation of the incorrect compound. We show that the mathematical framework for increased substrate selectivity in our model is analogous to the classic proofreading mechanism originally proposed for tRNA synthase; however, because the transport cycle is reversible we identified conditions in which the selectivity is essentially infinite and incorrect substrates are exported from the cell in a 'detoxification' mode. The cellular consequences of proofreading and membrane slippage are discussed as well as the impact on future drug development.


Assuntos
Sítios de Ligação , Transporte Biológico/fisiologia , Proteínas de Membrana Transportadoras , Modelos Biológicos , Ligação Proteica/fisiologia , Biologia Computacional , Humanos , Cinética , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/metabolismo , Simulação de Dinâmica Molecular , Transportador 1 de Glucose-Sódio , Especificidade por Substrato
13.
Artigo em Inglês | MEDLINE | ID: mdl-32687406

RESUMO

Severe acute respiratory syndrome coronavirus (SARS-CoV), an enveloped virus with a positive-sense single-stranded RNA genome, facilitates the host cell entry through intricate interactions with proteins and lipids of the cell membrane. The detailed molecular mechanism involves binding to the host cell receptor and fusion at the plasma membrane or after being trafficked to late endosomes under favorable environmental conditions. A crucial event in the process is the proteolytic cleavage of the viral spike protein by the host's endogenous proteases that releases the fusion peptide enabling fusion with the host cellular membrane system. The present review details the mechanism of viral fusion with the host and highlights the therapeutic options that prevent SARS-CoV-2 entry in humans.


Assuntos
Betacoronavirus/metabolismo , Membrana Celular/metabolismo , Infecções por Coronavirus/metabolismo , Infecções por Coronavirus/prevenção & controle , Pandemias/prevenção & controle , Pneumonia Viral/metabolismo , Pneumonia Viral/prevenção & controle , Proteínas Virais de Fusão/metabolismo , Sequência de Aminoácidos , Animais , Betacoronavirus/efeitos dos fármacos , Membrana Celular/efeitos dos fármacos , Membrana Celular/virologia , Humanos , Peptidil Dipeptidase A/metabolismo , Inibidores de Proteases/farmacologia , Inibidores de Proteases/uso terapêutico , Ligação Proteica/efeitos dos fármacos , Ligação Proteica/fisiologia , Glicoproteína da Espícula de Coronavírus/antagonistas & inibidores , Glicoproteína da Espícula de Coronavírus/metabolismo , Proteínas Virais de Fusão/efeitos dos fármacos
14.
Hum Genomics ; 14(1): 20, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: covidwho-526827

RESUMO

Coronavirus disease 2019 (COVID-19) is a declared pandemic that is spreading all over the world at a dreadfully fast rate. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the pathogen of COVID-19, infects the human body using angiotensin-converting enzyme 2 (ACE2) as a receptor identical to the severe acute respiratory syndrome (SARS) pandemic that occurred in 2002-2003. SARS-CoV-2 has a higher binding affinity to human ACE2 than to that of other species. Animal models that mimic the human disease are highly essential to develop therapeutics and vaccines against COVID-19. Here, we review transgenic mice that express human ACE2 in the airway and other epithelia and have shown to develop a rapidly lethal infection after intranasal inoculation with SARS-CoV, the pathogen of SARS. This literature review aims to present the importance of utilizing the human ACE2 transgenic mouse model to better understand the pathogenesis of COVID-19 and develop both therapeutics and vaccines.


Assuntos
Betacoronavirus/metabolismo , Infecções por Coronavirus/patologia , Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/patologia , Animais , Betacoronavirus/patogenicidade , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pandemias , Regiões Promotoras Genéticas/genética , Ligação Proteica/fisiologia , Receptores Virais/genética , Receptores Virais/metabolismo
15.
Hum Genomics ; 14(1): 20, 2020 06 04.
Artigo em Inglês | MEDLINE | ID: mdl-32498696

RESUMO

Coronavirus disease 2019 (COVID-19) is a declared pandemic that is spreading all over the world at a dreadfully fast rate. Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the pathogen of COVID-19, infects the human body using angiotensin-converting enzyme 2 (ACE2) as a receptor identical to the severe acute respiratory syndrome (SARS) pandemic that occurred in 2002-2003. SARS-CoV-2 has a higher binding affinity to human ACE2 than to that of other species. Animal models that mimic the human disease are highly essential to develop therapeutics and vaccines against COVID-19. Here, we review transgenic mice that express human ACE2 in the airway and other epithelia and have shown to develop a rapidly lethal infection after intranasal inoculation with SARS-CoV, the pathogen of SARS. This literature review aims to present the importance of utilizing the human ACE2 transgenic mouse model to better understand the pathogenesis of COVID-19 and develop both therapeutics and vaccines.


Assuntos
Betacoronavirus/metabolismo , Infecções por Coronavirus/patologia , Peptidil Dipeptidase A/genética , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/patologia , Animais , Betacoronavirus/patogenicidade , Modelos Animais de Doenças , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pandemias , Regiões Promotoras Genéticas/genética , Ligação Proteica/fisiologia , Receptores Virais/genética , Receptores Virais/metabolismo
16.
Nat Chem Biol ; 16(8): 866-875, 2020 08.
Artigo em Inglês | MEDLINE | ID: mdl-32483380

RESUMO

Changes in the cellular environment modulate protein energy landscapes to drive important biology, with consequences for signaling, allostery and other vital processes. The effects of ubiquitination are particularly important because of their potential influence on degradation by the 26S proteasome. Moreover, proteasomal engagement requires unstructured initiation regions that many known proteasome substrates lack. To assess the energetic effects of ubiquitination and how these manifest at the proteasome, we developed a generalizable strategy to produce isopeptide-linked ubiquitin within structured regions of a protein. The effects on the energy landscape vary from negligible to dramatic, depending on the protein and site of ubiquitination. Ubiquitination at sensitive sites destabilizes the native structure and increases the rate of proteasomal degradation. In well-folded proteins, ubiquitination can even induce the requisite unstructured regions needed for proteasomal engagement. Our results indicate a biophysical role of site-specific ubiquitination as a potential regulatory mechanism for energy-dependent substrate degradation.


Assuntos
Complexo de Endopeptidases do Proteassoma/metabolismo , Ubiquitina/química , Ubiquitinação/genética , Animais , Proteínas de Bactérias/metabolismo , Humanos , Camundongos , Poliubiquitina/metabolismo , Complexo de Endopeptidases do Proteassoma/química , Complexo de Endopeptidases do Proteassoma/genética , Ligação Proteica/fisiologia , Proteólise , Ribonucleases/metabolismo , Ubiquitina/metabolismo , Ubiquitinação/fisiologia
17.
Nat Commun ; 11(1): 2663, 2020 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-32471988

RESUMO

Endosomal sorting complexes for transport-III (ESCRT-III) assemble in vivo onto membranes with negative Gaussian curvature. How membrane shape influences ESCRT-III polymerization and how ESCRT-III shapes membranes is yet unclear. Human core ESCRT-III proteins, CHMP4B, CHMP2A, CHMP2B and CHMP3 are used to address this issue in vitro by combining membrane nanotube pulling experiments, cryo-electron tomography and AFM. We show that CHMP4B filaments preferentially bind to flat membranes or to tubes with positive mean curvature. Both CHMP2B and CHMP2A/CHMP3 assemble on positively curved membrane tubes. Combinations of CHMP4B/CHMP2B and CHMP4B/CHMP2A/CHMP3 are recruited to the neck of pulled membrane tubes and reshape vesicles into helical "corkscrew-like" membrane tubes. Sub-tomogram averaging reveals that the ESCRT-III filaments assemble parallel and locally perpendicular to the tube axis, highlighting the mechanical stresses imposed by ESCRT-III. Our results underline the versatile membrane remodeling activity of ESCRT-III that may be a general feature required for cellular membrane remodeling processes.


Assuntos
Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Membranas Artificiais , Estresse Mecânico , ATPases Associadas a Diversas Atividades Celulares/metabolismo , Fenômenos Bioquímicos , Microscopia Crioeletrônica , Humanos , Nanotubos , Polimerização , Ligação Proteica/fisiologia , Multimerização Proteica , ATPases Vacuolares Próton-Translocadoras/metabolismo
18.
Nat Commun ; 11(1): 2242, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32382052

RESUMO

Proteins KaiA, KaiB and KaiC constitute a biochemical circadian oscillator in the cyanobacterium Synechococcus elongatus. It has been reported kaiA inactivation completely abolishes circadian oscillations. However, we show here that kaiBC promoter activity exhibits a damped, low-amplitude oscillation with a period of approximately 24 h in kaiA-inactivated strains. The damped rhythm resonates with external cycles with a period of 24-26 h, indicating that its natural frequency is similar to that of the circadian clock. Double-mutation experiments reveal that kaiC, kaiB, and sasA (encoding a KaiC-binding histidine kinase) are all required for the damped oscillation. Further analysis suggests that the kaiA-less damped transcriptional rhythm requires KaiB-KaiC complex formation and the transcription-translation feedback loop, but not the KaiC phosphorylation cycle. Our results provide insights into mechanisms that could potentially underlie the diurnal/circadian behaviors observed in other bacterial species that possess kaiB and kaiC homologues but lack a kaiA homologue.


Assuntos
Ritmo Circadiano/fisiologia , Synechococcus/metabolismo , Synechococcus/fisiologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Western Blotting , Ritmo Circadiano/genética , Medições Luminescentes , Modelos Teóricos , Ligação Proteica/genética , Ligação Proteica/fisiologia , Synechococcus/genética
19.
Nat Commun ; 11(1): 2246, 2020 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-32382059

RESUMO

Graft versus host disease (GvHD) is the main complication of allogeneic hematopoietic stem cell transplantation (HSCT). Here we report studies of a patient with chronic GvHD (cGvHD) carrying persistent CD4+ T cell clonal expansion harboring somatic mTOR, NFKB2, and TLR2 mutations. In the screening cohort (n = 134), we detect the mTOR P2229R kinase domain mutation in two additional cGvHD patients, but not in healthy or HSCT patients without cGvHD. Functional analyses of the mTOR mutation indicate a gain-of-function alteration and activation of both mTORC1 and mTORC2 signaling pathways, leading to increased cell proliferation and decreased apoptosis. Single-cell RNA sequencing and real-time impedance measurements support increased cytotoxicity of mutated CD4+ T cells. High throughput drug-sensitivity testing suggests that mutations induce resistance to mTOR inhibitors, but increase sensitivity for HSP90 inhibitors. Our findings imply that somatic mutations may contribute to aberrant T cell proliferations and persistent immune activation in cGvHD, thereby paving the way for targeted therapies.


Assuntos
Doença Enxerto-Hospedeiro/genética , Linfócitos T/metabolismo , Serina-Treonina Quinases TOR/genética , Western Blotting , Proliferação de Células/genética , Proliferação de Células/fisiologia , Células HEK293 , Humanos , Imunidade Celular/genética , Imunidade Celular/fisiologia , Imunoprecipitação , Mutação/genética , Ligação Proteica/genética , Ligação Proteica/fisiologia
20.
PLoS Pathog ; 16(4): e1008541, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-32353058

RESUMO

Ehrlichia chaffeensis (E. chaffeensis) exploits evolutionarily conserved Notch and Wnt host cell signaling pathways to downregulate innate immune host defenses and promote infection. The multifunctional E. chaffeensis TRP120 effector which has HECT E3 ubiquitin ligase activity, interacts with the host nuclear tumor suppressor F-BOX and WD domain repeating-containing 7 (FBW7). FBW7 is the substrate recognition subunit of the Skp1-cullin-1-FBOX E3 ubiquitin (Ub) ligase complex (SCF) known to negatively regulate a network of oncoproteins (Notch, cyclin E, c-Jun, MCL1 and cMYC). In this study, we demonstrate that TRP120 and FBW7 colocalize strongly in the nucleus by confocal immunofluorescent microscopy and interactions between TRP120 and FBW7 FBOX and WD40 domains were demonstrated by ectopic expression and co-immunoprecipitation. Although FBW7 gene expression increased during E. chaffeensis infection, FBW7 levels significantly decreased (>70%) by 72 h post infection. Moreover, an iRNA knockdown of FBW7 coincided with increased E. chaffeensis infection and levels of Notch intracellular domain (NICD), phosphorylated c-Jun, MCL-1 and cMYC, which are negatively regulated by FBW7. An increase in FBW7 K48 ubiquitination was detected during infection by co-IP, and FBW7 degradation was inhibited in infected cells treated with the proteasomal inhibitor bortezomib. Direct TRP120 ubiquitination of native and recombinant FBW7 was demonstrated in vitro and confirmed by ectopic expression of TRP120 HECT Ub ligase catalytic site mutant. This study identifies the tumor suppressor, FBW7, as a TRP120 HECT E3 Ub ligase substrate, and demonstrates that TRP120 ligase activity promotes ehrlichial infection by degrading FBW7 to maintain stability of Notch and other oncoproteins involved in cell survival and apoptosis.


Assuntos
Ehrlichia chaffeensis/metabolismo , Ehrlichiose/genética , Proteína 7 com Repetições F-Box-WD/metabolismo , Apoptose/fisiologia , Proteínas de Bactérias/metabolismo , Proteínas de Ciclo Celular/metabolismo , Ehrlichia chaffeensis/genética , Ehrlichia chaffeensis/fisiologia , Ehrlichiose/metabolismo , Proteínas F-Box/metabolismo , Proteína 7 com Repetições F-Box-WD/genética , Interações Hospedeiro-Patógeno , Humanos , Proteínas Oncogênicas/genética , Ligação Proteica/fisiologia , Células THP-1 , Ubiquitina-Proteína Ligases/metabolismo , Ubiquitinação
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