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1.
Ecotoxicol Environ Saf ; 270: 115925, 2024 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-38183752

RESUMO

Disinfection by-products (DBPs), including trihalomethanes (THMs) and haloacetic acids (HAAs), have attracted attention due to their carcinogenic properties, leading to varying conclusions. This meta-analysis aimed to evaluate the dose-response relationship and the dose-dependent effect of DBPs on cancer risk. We performed a selective search in PubMed, Web of Science, and Embase databases for articles published up to September 15th, 2023. Our meta-analysis eventually included 25 articles, encompassing 8 cohort studies with 6038,525 participants and 10,668 cases, and 17 case-control studies with 10,847 cases and 20,702 controls. We observed a positive correlation between increased cancer risk and higher concentrations of total trihalomethanes (TTHM) in water, longer exposure durations, and higher cumulative TTHM intake. These associations showed a linear trend, with relative risks (RRs) and 95 % confidence intervals (CIs) being 1.02 (1.01-1.03), 1.04 (1.02-1.06), and 1.02 (1.00-1.03), respectively. Gender-specific analyses revealed slightly U-shaped relationships in both males and females, with males exhibiting higher risks. The threshold dose for TTHM in relation to cancer risk was determined to be 55 µg/L for females and 40 µg/L for males. A linear association was also identified between bladder cancer risk and TTHM exposure, with an RR and 95 % CI of 1.08 (1.05-1.11). Positive linear associations were observed between cancer risk and exposure to chloroform, bromodichloromethane (BDCM), and HAA5, with RRs and 95 % CIs of 1.02 (1.01-1.03), 1.33 (1.18-1.50), and 1.07 (1.03-1.12), respectively. Positive dose-dependent effects were noted for brominated THMs above 35 µg/L and chloroform above 75 µg/L. While heterogeneity was observed in the studies for quantitative synthesis, no publication bias was detected. Exposure to TTHM, chloroform, BDCM, or HAA5 may contribute to carcinogenesis, and the risk of cancer appears to be dose-dependent on DBP exposure levels. A cumulative effect is suggested by the positive correlation between TTHM exposure and cancer risk. Bladder cancer and endocrine-related cancers show dose-dependent and positive associations with TTHM exposure. Males may be more susceptible to TTHM compared to females.


Assuntos
Desinfetantes , Neoplasias da Bexiga Urinária , Poluentes Químicos da Água , Masculino , Feminino , Humanos , Desinfecção , Clorofórmio/análise , Trialometanos/toxicidade , Trialometanos/análise , Poluentes Químicos da Água/toxicidade , Poluentes Químicos da Água/análise , Desinfetantes/toxicidade
2.
Nat Chem Biol ; 16(5): 529-537, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32152540

RESUMO

Combination antiretroviral therapy has transformed HIV-1 infection, once a fatal illness, into a manageable chronic condition. Drug resistance, severe side effects and treatment noncompliance bring challenges to combination antiretroviral therapy implementation in clinical settings and indicate the need for additional molecular targets. Here, we have identified several small-molecule fusion inhibitors, guided by a neutralizing antibody, against an extensively studied vaccine target-the membrane proximal external region (MPER) of the HIV-1 envelope spike. These compounds specifically inhibit the HIV-1 envelope-mediated membrane fusion by blocking CD4-induced conformational changes. An NMR structure of one compound complexed with a trimeric MPER construct reveals that the compound partially inserts into a hydrophobic pocket formed exclusively by the MPER residues, thereby stabilizing its prefusion conformation. These results suggest that the MPER is a potential therapeutic target for developing fusion inhibitors and that strategies employing an antibody-guided search for novel therapeutics may be applied to other human diseases.


Assuntos
Fármacos Anti-HIV/química , Fármacos Anti-HIV/farmacologia , Proteína gp41 do Envelope de HIV/química , Proteína gp41 do Envelope de HIV/metabolismo , Internalização do Vírus/efeitos dos fármacos , Sítios de Ligação , Antígenos CD4/metabolismo , Membrana Celular/metabolismo , Dequalínio/química , Dequalínio/farmacologia , Avaliação Pré-Clínica de Medicamentos/métodos , Polarização de Fluorescência , Células HEK293 , Proteína gp41 do Envelope de HIV/genética , HIV-1/patogenicidade , Humanos , Interações Hidrofóbicas e Hidrofílicas , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Mutação , Bibliotecas de Moléculas Pequenas/química , Bibliotecas de Moléculas Pequenas/farmacologia , Relação Estrutura-Atividade , Ressonância de Plasmônio de Superfície
3.
Biophys J ; 118(2): 396-402, 2020 01 21.
Artigo em Inglês | MEDLINE | ID: mdl-31870540

RESUMO

Fatty acid binding proteins play an important role in the transportation of fatty acids. Despite intensive studies, how fatty acids enter the protein cavity for binding is still controversial. Here, a gap-closed variant of human intestinal fatty acid binding protein was generated by mutagenesis, in which the gap is locked by a disulfide bridge. According to its structure determined here by NMR, this variant has no obvious openings as the ligand entrance and the gap cannot be widened by internal dynamics. Nevertheless, it still takes up fatty acids and other ligands. NMR relaxation dispersion, chemical exchange saturation transfer, and hydrogen-deuterium exchange experiments show that the variant exists in a major native state, two minor native-like states, and two locally unfolded states in aqueous solution. Local unfolding of either ßB-ßD or helix 2 can generate an opening large enough for ligands to enter the protein cavity, but only the fast local unfolding of helix 2 is relevant to the ligand entry process.


Assuntos
Proteínas de Ligação a Ácido Graxo/química , Proteínas de Ligação a Ácido Graxo/metabolismo , Desdobramento de Proteína , Humanos , Ligantes , Modelos Moleculares , Ligação Proteica , Estrutura Secundária de Proteína
4.
BMC Plant Biol ; 17(1): 68, 2017 03 31.
Artigo em Inglês | MEDLINE | ID: mdl-28359256

RESUMO

BACKGROUND: Hevein-like peptides are a family of cysteine-rich and chitin-binding peptides consisting of 29-45 amino acids. Their chitin-binding property is essential for plant defense against fungi. Based on the number of cysteine residues in their sequences, they are divided into three sub-families: 6C-, 8C- and 10C-hevein-like peptides. All three subfamilies contain a three-domain precursor comprising a signal peptide, a mature hevein-like peptide and a C-terminal domain comprising a hinge region with protein cargo in 8C- and 10C-hevein-like peptides. RESULTS: Here we report the isolation and characterization of two novel 8C-hevein-like peptides, designated morintides (mO1 and mO2), from the drumstick tree Moringa oleifera, a drought-resistant tree belonging to the Moringaceae family. Proteomic analysis revealed that morintides comprise 44 amino acid residues and are rich in cysteine, glycine and hydrophilic amino acid residues such as asparagine and glutamine. Morintides are resistant to thermal and enzymatic degradation, able to bind to chitin and inhibit the growth of phyto-pathogenic fungi. Transcriptomic analysis showed that they contain a three-domain precursor comprising an endoplasmic reticulum (ER) signal sequence, a mature peptide domain and a C-terminal domain. A striking feature distinguishing morintides from other 8C-hevein-like peptides is a short and protein-cargo-free C-terminal domain. Previously, a similar protein-cargo-free C-terminal domain has been observed only in ginkgotides, the 8C-hevein-like peptides from a gymnosperm Ginkgo biloba. Thus, morintides, with a cargo-free C-terminal domain, are a stand-alone class of 8C-hevein-like peptides from angiosperms. CONCLUSIONS: Our results expand the existing library of hevein-like peptides and shed light on molecular diversity within the hevein-like peptide family. Our work also sheds light on the anti-fungal activity and stability of 8C-hevein-like peptides.


Assuntos
Quitina/metabolismo , Moringa oleifera/química , Peptídeos/metabolismo , Peptídeos/farmacologia , Proteínas de Plantas/metabolismo , Animais , Antifúngicos/química , Antifúngicos/farmacologia , Peptídeos Catiônicos Antimicrobianos/química , Chlorocebus aethiops , Avaliação Pré-Clínica de Medicamentos/métodos , Testes de Sensibilidade Microbiana , Ressonância Magnética Nuclear Biomolecular , Peptídeos/química , Peptídeos/genética , Filogenia , Lectinas de Plantas/química , Proteínas de Plantas/química , Proteínas de Plantas/genética , Estabilidade Proteica , Células Vero
5.
Angew Chem Int Ed Engl ; 55(24): 6869-72, 2016 06 06.
Artigo em Inglês | MEDLINE | ID: mdl-27105780

RESUMO

Fatty acid binding proteins are responsible for the transportation of fatty acids in biology. Despite intensive studies, the molecular mechanism of fatty acid entry to and exit from the protein cavity is still unclear. Here a cap-closed variant of human intestinal fatty acid binding protein was generated by mutagenesis, in which the helical cap is locked to the ß-barrel by a disulfide linkage. Structure determination shows that this variant adopts a closed conformation, but still uptakes fatty acids. Stopped-flow experiments indicate that a rate-limiting step exists before the ligand association and this step corresponds to the conversion of the closed form to the open one. NMR relaxation dispersion and H-D exchange data demonstrate the presence of two excited states: one is native-like, but the other adopts a locally unfolded structure. Local unfolding of helix 2 generates an opening for ligands to enter the protein cavity, and thus controls the ligand association rate.

6.
Angew Chem Int Ed Engl ; 53(9): 2358-61, 2014 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-24470381

RESUMO

A protein can exist in multiple states under native conditions and those states with low populations are often critical to biological function and self-assembly. To investigate the role of the minor states of an acyl carrier protein, NMR techniques were applied to determine the number of minor states and characterize their structures and kinetics. The acyl carrier protein from Micromonospora echinospora was found to exist in one major folded state (95.2%), one unfolded state (4.1%), and one intermediate state (0.7%) under native conditions. The three states are in dynamic equilibrium and the intermediate state very likely adopts a native-like structure and is an off-pathway folding product. The intermediate state may mediate the formation of oligomers in vitro and play an important role in the recognition of partner enzymes in vivo.


Assuntos
Proteína de Transporte de Acila/química , Proteínas de Bactérias/química , Micromonospora/química , Dobramento de Proteína , Cinética , Modelos Moleculares , Ressonância Magnética Nuclear Biomolecular , Conformação Proteica
7.
Antiviral Res ; 224: 105834, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38369246

RESUMO

Neutralizing antibodies (NAbs) are naturally produced by our immune system to combat viral infections. Clinically, neutralizing antibodies with potent efficacy and high specificity have been extensively used to prevent and treat a wide variety of viral infections, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), Human Immunodeficiency Virus (HIV), Dengue Virus (DENV) and Hepatitis B Virus (HBV). An overwhelmingly large subset of clinically effective NAbs operates by targeting viral envelope proteins to inhibit viral entry into the host cell. Binding of viral envelope protein to the host receptor is a critical rate limiting step triggering a cascade of downstream events, including endocytosis, membrane fusion and pore formation to allow viral entry. In recent years, improved structural knowledge on these processes have allowed researchers to also leverage NAbs as an indispensable tool in guiding discovery of novel antiviral entry inhibitors, providing drug candidates with high efficacy and pan-genus specificity. This review will summarize the latest progresses on the applications of NAbs as effective entry inhibitors and as important tools to develop antiviral therapeutics by high-throughput drug screenings, rational design of peptidic entry inhibitor mimicking NAbs and in silico computational modeling approaches.


Assuntos
Anticorpos Neutralizantes , Viroses , Humanos , Internalização do Vírus , Proteínas do Envelope Viral , Antivirais/farmacologia , Anticorpos Antivirais
8.
Nat Struct Mol Biol ; 30(7): 980-990, 2023 07.
Artigo em Inglês | MEDLINE | ID: mdl-37430064

RESUMO

The Omicron subvariant BA.2 has become the dominant circulating strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in many countries. Here, we have characterized structural, functional and antigenic properties of the full-length BA.2 spike (S) protein and compared replication of the authentic virus in cell culture and an animal model with previously prevalent variants. BA.2 S can fuse membranes slightly more efficiently than Omicron BA.1, but still less efficiently than other previous variants. Both BA.1 and BA.2 viruses replicated substantially faster in animal lungs than the early G614 (B.1) strain in the absence of pre-existing immunity, possibly explaining the increased transmissibility despite their functionally compromised spikes. As in BA.1, mutations in the BA.2 S remodel its antigenic surfaces, leading to strong resistance to neutralizing antibodies. These results suggest that both immune evasion and replicative advantage may contribute to the heightened transmissibility of the Omicron subvariants.


Assuntos
COVID-19 , Animais , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética
9.
Sci Immunol ; 7(78): eabp8328, 2022 12 23.
Artigo em Inglês | MEDLINE | ID: mdl-35549298

RESUMO

Key features of immune memory are greater and faster antigen-specific antibody responses to repeat infection. In the setting of immune-evading viral evolution, it is important to understand how far antibody memory recognition stretches across viral variants when memory cells are recalled to action by repeat invasions. It is also important to understand how immune recall influences longevity of secreted antibody responses. We analyzed SARS-CoV-2 variant recognition; dynamics of memory B cells; and secreted antibody over time after infection, vaccination, and boosting. We find that a two-dose SARS-CoV-2 vaccination regimen given after natural infection generated greater longitudinal antibody stability and induced maximal antibody magnitudes with enhanced breadth across Beta, Gamma, Delta and Omicron variants. A homologous third messenger RNA vaccine dose in COVID-naïve individuals conferred greater cross-variant evenness of neutralization potency with stability that was equal to the hybrid immunity conferred by infection plus vaccination. Within unvaccinated individuals who recovered from COVID, enhanced antibody stability over time was observed within a subgroup of individuals who recovered more quickly from COVID and harbored significantly more memory B cells cross-reactive to endemic coronaviruses early after infection. These cross-reactive clones map to the conserved S2 region of SARS-CoV-2 spike with higher somatic hypermutation levels and greater target affinity. We conclude that SARS-CoV-2 antigen challenge histories in humans influence not only the speed and magnitude of antibody responses but also functional cross-variant antibody repertoire composition and longevity.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos , Vacinas contra COVID-19 , Anticorpos
10.
Cell Rep ; 39(4): 110729, 2022 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-35452593

RESUMO

The Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), bearing an unusually high number of mutations, has become a dominant strain in many countries within several weeks. We report here structural, functional, and antigenic properties of its full-length spike (S) protein with a native sequence in comparison with those of previously prevalent variants. Omicron S requires a substantially higher level of host receptor ACE2 for efficient membrane fusion than other variants, possibly explaining its unexpected cellular tropism. Mutations not only remodel the antigenic structure of the N-terminal domain of the S protein but also alter the surface of the receptor-binding domain in a way not seen in other variants, consistent with its remarkable resistance to neutralizing antibodies. These results suggest that Omicron S has acquired an extraordinary ability to evade host immunity by excessive mutations, which also compromise its fusogenic capability.


Assuntos
COVID-19 , SARS-CoV-2 , COVID-19/genética , Humanos , Mutação/genética , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus
11.
Sci Adv ; 8(49): eabq6527, 2022 12 09.
Artigo em Inglês | MEDLINE | ID: mdl-36475798

RESUMO

As severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) evolves to escape natural antibodies, it also loses sensitivity to therapeutic antibody drugs. By contrast, evolution selects for binding to ACE2, the cell-surface receptor required for SARS-CoV-2 infection. Consistent with this, we find that an ACE2 decoy neutralizes antibody-resistant variants, including Omicron, with no loss in potency. To identify design features necessary for in vivo activity, we compare several enzymatically inactive, Fc effector-silenced ACE2-Fc decoys. Inclusion of the ACE2 collectrin-like domain not only improves affinity for the S protein but also unexpectedly extends serum half-life and is necessary to reduce disease severity and viral titer in Syrian hamsters. Fc effector function is not required. The activity of ACE2 decoy receptors is due, in part, to their ability to trigger an irreversible structural change in the viral S protein. Our studies provide a new understanding of how ACE2 decoys function and support their development as therapeutics to treat ACE2-dependent coronaviruses.


Assuntos
COVID-19 , SARS-CoV-2 , Humanos
12.
bioRxiv ; 2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35547850

RESUMO

The Omicron subvariant BA.2 has become the dominant circulating strain of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in many countries. We have characterized structural, functional and antigenic properties of the full-length BA.2 spike (S) protein and compared replication of the authentic virus in cell culture and animal model with previously prevalent variants. BA.2 S can fuse membranes more efficiently than Omicron BA.1, mainly due to lack of a BA.1-specific mutation that may retard the receptor engagement, but still less efficiently than other variants. Both BA.1 and BA.2 viruses replicated substantially faster in animal lungs than the early G614 (B.1) strain in the absence of pre-existing immunity, possibly explaining the increased transmissibility despite their functionally compromised spikes. As in BA.1, mutations in the BA.2 S remodel its antigenic surfaces leading to strong resistance to neutralizing antibodies. These results suggest that both immune evasion and replicative advantage may contribute to the heightened transmissibility for the Omicron subvariants.

13.
Viruses ; 13(5)2021 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-33922579

RESUMO

HIV-1 (human immunodeficiency virus type 1) infection begins with the attachment of the virion to a host cell by its envelope glycoprotein (Env), which subsequently induces fusion of viral and cell membranes to allow viral entry. Upon binding to primary receptor CD4 and coreceptor (e.g., chemokine receptor CCR5 or CXCR4), Env undergoes large conformational changes and unleashes its fusogenic potential to drive the membrane fusion. The structural biology of HIV-1 Env and its complexes with the cellular receptors not only has advanced our knowledge of the molecular mechanism of how HIV-1 enters the host cells but also provided a structural basis for the rational design of fusion inhibitors as potential antiviral therapeutics. In this review, we summarize our latest understanding of the HIV-1 membrane fusion process and discuss related therapeutic strategies to block viral entry.


Assuntos
Inibidores da Fusão de HIV/farmacologia , HIV-1/efeitos dos fármacos , HIV-1/fisiologia , Fusão de Membrana/efeitos dos fármacos , Internalização do Vírus/efeitos dos fármacos , Antirretrovirais/farmacologia , Inibidores da Fusão de HIV/classificação , Infecções por HIV/virologia , Humanos
14.
Curr Opin Virol ; 50: 173-182, 2021 10.
Artigo em Inglês | MEDLINE | ID: mdl-34534731

RESUMO

The COVID-19 (coronavirus disease 2019) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has led to loss of human life in millions and devastating socio-economic consequences worldwide. The disease has created urgent needs for intervention strategies to control the crisis and meeting these needs requires a deep understanding of the structure-function relationships of viral proteins and relevant host factors. The trimeric spike (S) protein of the virus decorates the viral surface and is an important target for development of diagnostics, therapeutics and vaccines. Rapid progress in the structural biology of SARS-CoV-2 S protein has been made since the early stage of the pandemic, advancing our knowledge on the viral entry process considerably. In this review, we summarize our latest understanding of the structure of the SARS-CoV-2 S protein and discuss the implications for vaccines and therapeutics.


Assuntos
Glicoproteína da Espícula de Coronavírus/química , Enzima de Conversão de Angiotensina 2/química , Sítios de Ligação , Vacinas contra COVID-19/imunologia , Domínios Proteicos , Glicoproteína da Espícula de Coronavírus/fisiologia
15.
Science ; 372(6541): 525-530, 2021 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-33727252

RESUMO

Substitution for aspartic acid (D) by glycine (G) at position 614 in the spike (S) protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appears to facilitate rapid viral spread. The G614 strain and its recent variants are now the dominant circulating forms. Here, we report cryo-electron microscopy structures of a full-length G614 S trimer, which adopts three distinct prefusion conformations that differ primarily by the position of one receptor-binding domain. A loop disordered in the D614 S trimer wedges between domains within a protomer in the G614 spike. This added interaction appears to prevent premature dissociation of the G614 trimer-effectively increasing the number of functional spikes and enhancing infectivity-and to modulate structural rearrangements for membrane fusion. These findings extend our understanding of viral entry and suggest an improved immunogen for vaccine development.


Assuntos
SARS-CoV-2/química , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Substituição de Aminoácidos , Enzima de Conversão de Angiotensina 2/química , Enzima de Conversão de Angiotensina 2/metabolismo , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/metabolismo , COVID-19/virologia , Microscopia Crioeletrônica , Humanos , Interações Hidrofóbicas e Hidrofílicas , Modelos Moleculares , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Ligação Proteica , Conformação Proteica , Domínios Proteicos , Subunidades Proteicas/química , Subunidades Proteicas/metabolismo , Receptores de Coronavírus/química , Receptores de Coronavírus/metabolismo , SARS-CoV-2/fisiologia , Glicoproteína da Espícula de Coronavírus/imunologia , Glicoproteína da Espícula de Coronavírus/metabolismo , Internalização do Vírus
16.
bioRxiv ; 2021 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-33880477

RESUMO

Several fast-spreading variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have become the dominant circulating strains that continue to fuel the COVID-19 pandemic despite intensive vaccination efforts throughout the world. We report here cryo-EM structures of the full-length spike (S) trimers of the B.1.1.7 and B.1.351 variants, as well as their biochemical and antigenic properties. Mutations in the B.1.1.7 protein increase the accessibility of its receptor binding domain and also the binding affinity for receptor angiotensin-converting enzyme 2 (ACE2). The enhanced receptor engagement can account for the increased transmissibility and risk of mortality as the variant may begin to infect efficiently infect additional cell types expressing low levels of ACE2. The B.1.351 variant has evolved to reshape antigenic surfaces of the major neutralizing sites on the S protein, rendering complete resistance to some potent neutralizing antibodies. These findings provide structural details on how the wide spread of SARS-CoV-2 enables rapid evolution to enhance viral fitness and immune evasion. They may guide intervention strategies to control the pandemic.

17.
Science ; 373(6555): 642-648, 2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34168070

RESUMO

Several fast-spreading variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have become the dominant circulating strains in the COVID-19 pandemic. We report here cryo-electron microscopy structures of the full-length spike (S) trimers of the B.1.1.7 and B.1.351 variants, as well as their biochemical and antigenic properties. Amino acid substitutions in the B.1.1.7 protein increase both the accessibility of its receptor binding domain and the binding affinity for receptor angiotensin-converting enzyme 2 (ACE2). The enhanced receptor engagement may account for the increased transmissibility. The B.1.351 variant has evolved to reshape antigenic surfaces of the major neutralizing sites on the S protein, making it resistant to some potent neutralizing antibodies. These findings provide structural details on how SARS-CoV-2 has evolved to enhance viral fitness and immune evasion.


Assuntos
COVID-19/virologia , Evasão da Resposta Imune , SARS-CoV-2/química , SARS-CoV-2/patogenicidade , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologia , Substituição de Aminoácidos , Enzima de Conversão de Angiotensina 2/metabolismo , Anticorpos Antivirais/imunologia , Antígenos Virais/imunologia , Microscopia Crioeletrônica , Células HEK293 , Humanos , Modelos Moleculares , Mutação , Ligação Proteica , Conformação Proteica , Domínios Proteicos , Domínios e Motivos de Interação entre Proteínas , Subunidades Proteicas/química , Receptores de Coronavírus/metabolismo , SARS-CoV-2/genética , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo
18.
bioRxiv ; 2021 Aug 17.
Artigo em Inglês | MEDLINE | ID: mdl-34426810

RESUMO

The Delta variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has outcompeted previously prevalent variants and become a dominant strain worldwide. We report here structure, function and antigenicity of its full-length spike (S) trimer in comparison with those of other variants, including Gamma, Kappa, and previously characterized Alpha and Beta. Delta S can fuse membranes more efficiently at low levels of cellular receptor ACE2 and its pseudotyped viruses infect target cells substantially faster than all other variants tested, possibly accounting for its heightened transmissibility. Mutations of each variant rearrange the antigenic surface of the N-terminal domain of the S protein in a unique way, but only cause local changes in the receptor-binding domain, consistent with greater resistance particular to neutralizing antibodies. These results advance our molecular understanding of distinct properties of these viruses and may guide intervention strategies.

19.
Science ; 374(6573): 1353-1360, 2021 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-34698504

RESUMO

The Delta variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has outcompeted previously prevalent variants and become a dominant strain worldwide. We report the structure, function, and antigenicity of its full-length spike (S) trimer as well as those of the Gamma and Kappa variants, and compare their characteristics with the G614, Alpha, and Beta variants. Delta S can fuse membranes more efficiently at low levels of cellular receptor angiotensin converting enzyme 2 (ACE2), and its pseudotyped viruses infect target cells substantially faster than the other five variants, possibly accounting for its heightened transmissibility. Each variant shows different rearrangement of the antigenic surface of the amino-terminal domain of the S protein but only makes produces changes in the receptor binding domain (RBD), making the RBD a better target for therapeutic antibodies.


Assuntos
Evasão da Resposta Imune , Fusão de Membrana , SARS-CoV-2/imunologia , SARS-CoV-2/patogenicidade , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologia , Enzima de Conversão de Angiotensina 2/metabolismo , Anticorpos Antivirais/imunologia , Afinidade de Anticorpos , Antígenos Virais/imunologia , Linhagem Celular , Epitopos/imunologia , Humanos , Modelos Moleculares , Mutação , Conformação Proteica , Domínios Proteicos , Multimerização Proteica , Receptores de Coronavírus/metabolismo , SARS-CoV-2/química , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/fisiologia
20.
Nat Struct Mol Biol ; 28(2): 202-209, 2021 02.
Artigo em Inglês | MEDLINE | ID: mdl-33432247

RESUMO

Effective intervention strategies are urgently needed to control the COVID-19 pandemic. Human angiotensin-converting enzyme 2 (ACE2) is a membrane-bound carboxypeptidase that forms a dimer and serves as the cellular receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). ACE2 is also a key negative regulator of the renin-angiotensin system that modulates vascular functions. We report here the properties of a trimeric ACE2 ectodomain variant, engineered using a structure-based approach. The trimeric ACE2 variant has a binding affinity of ~60 pM for the spike protein of SARS­CoV­2 (compared with 77 nM for monomeric ACE2 and 12-22 nM for dimeric ACE2 constructs), and its peptidase activity and the ability to block activation of angiotensin II receptor type 1 in the renin-angiotensin system are preserved. Moreover, the engineered ACE2 potently inhibits SARS­CoV­2 infection in cell culture. These results suggest that engineered, trimeric ACE2 may be a promising anti-SARS-CoV-2 agent for treating COVID-19.


Assuntos
Enzima de Conversão de Angiotensina 2/química , Antivirais/química , Tratamento Farmacológico da COVID-19 , Enzima de Conversão de Angiotensina 2/genética , Enzima de Conversão de Angiotensina 2/uso terapêutico , Antivirais/uso terapêutico , Microscopia Crioeletrônica , Humanos , Modelos Moleculares , Engenharia de Proteínas , Multimerização Proteica , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/uso terapêutico , SARS-CoV-2/fisiologia
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