RESUMO
Epstein-Barr virus (EBV) is an oncogenic human herpesvirus that persists as a multicopy episome in proliferating host cells. Episome maintenance is strictly dependent on EBNA1, a sequence-specific DNA-binding protein with no known enzymatic activities. Here, we show that EBNA1 forms a cell cycle-dependent DNA crosslink with the EBV origin of plasmid replication oriP. EBNA1 tyrosine 518 (Y518) is essential for crosslinking to oriP and functionally required for episome maintenance and generation of EBV-transformed lymphoblastoid cell lines (LCLs). Mechanistically, Y518 is required for replication fork termination at oriP in vivo and for formation of SDS-resistant complexes in vitro. EBNA1-DNA crosslinking corresponds to single-strand endonuclease activity specific to DNA structures enriched at replication-termination sites, such as 4-way junctions. These findings reveal that EBNA1 forms tyrosine-dependent DNA-protein crosslinks and single-strand cleavage at oriP required for replication termination and viral episome maintenance.
Assuntos
Ciclo Celular , Reagentes de Ligações Cruzadas/química , DNA Viral/metabolismo , Antígenos Nucleares do Vírus Epstein-Barr/metabolismo , Plasmídeos/metabolismo , Origem de Replicação , Replicação Viral/fisiologia , Sequência de Aminoácidos , Linfócitos B/metabolismo , Linhagem Celular , Adutos de DNA/metabolismo , Replicação do DNA , Endonucleases/metabolismo , Antígenos Nucleares do Vírus Epstein-Barr/química , Antígenos Nucleares do Vírus Epstein-Barr/genética , Humanos , Mutação/genética , Ligação Proteica , Recombinação Genética/genética , Tirosina/metabolismoRESUMO
Strategies for installing authentic ADP-ribosylation (ADPr) at desired positions are fundamental for creating the tools needed to explore this elusive post-translational modification (PTM) in essential cellular processes. Here, we describe a phospho-guided chemoenzymatic approach based on the Ser-ADPr writer complex for rapid, scalable preparation of a panel of pure, precisely modified peptides. Integrating this methodology with phage display technology, we have developed site-specific as well as broad-specificity antibodies to mono-ADPr. These recombinant antibodies have been selected and characterized using multiple ADP-ribosylated peptides and tested by immunoblotting and immunofluorescence for their ability to detect physiological ADPr events. Mono-ADPr proteomics and poly-to-mono comparisons at the modification site level have revealed the prevalence of mono-ADPr upon DNA damage and illustrated its dependence on PARG and ARH3. These and future tools created on our versatile chemical biology-recombinant antibody platform have broad potential to elucidate ADPr signaling pathways in health and disease.
Assuntos
ADP-Ribosilação , Proteínas de Transporte/metabolismo , Proteínas Nucleares/metabolismo , Poli(ADP-Ribose) Polimerase-1/metabolismo , ADP-Ribosilação/efeitos dos fármacos , Sequência de Aminoácidos , Anticorpos/metabolismo , Benzimidazóis/farmacologia , Linhagem Celular Tumoral , Técnicas de Visualização da Superfície Celular , Dano ao DNA , Glicosídeo Hidrolases/metabolismo , Histonas/metabolismo , Humanos , Fosfatos/metabolismo , Monoéster Fosfórico Hidrolases/metabolismo , Ftalazinas/farmacologia , Piperazinas/farmacologia , Poli(ADP-Ribose) Polimerase-1/química , Proteínas Recombinantes/metabolismo , Serina/metabolismo , Tirosina/metabolismoRESUMO
The constituents of the gut microbiome are determined by the local habitat, which itself is shaped by immunological pressures, such as mucosal IgA. Using a mouse model of restricted antibody repertoire, we identified a role for antibody-microbe interactions in shaping a community of bacteria with an enhanced capacity to metabolize L-tyrosine. This model led to increased concentrations of p-cresol sulfate (PCS), which protected the host against allergic airway inflammation. PCS selectively reduced CCL20 production by airway epithelial cells due to an uncoupling of epidermal growth factor receptor (EGFR) and Toll-like receptor 4 (TLR4) signaling. Together, these data reveal a gut microbe-derived metabolite pathway that acts distally on the airway epithelium to reduce allergic airway responses, such as those underpinning asthma.
Assuntos
Anticorpos/metabolismo , Bactérias/metabolismo , Cresóis/metabolismo , Microbioma Gastrointestinal , Intestinos/microbiologia , Pulmão/metabolismo , Pneumonia/prevenção & controle , Hipersensibilidade Respiratória/prevenção & controle , Ésteres do Ácido Sulfúrico/metabolismo , Tirosina/metabolismo , Administração Oral , Alérgenos , Animais , Anticorpos/imunologia , Diversidade de Anticorpos , Bactérias/imunologia , Células Cultivadas , Quimiocina CCL20/metabolismo , Técnicas de Cocultura , Cresóis/administração & dosagem , Modelos Animais de Doenças , Receptores ErbB/metabolismo , Feminino , Interações Hospedeiro-Patógeno , Injeções Intravenosas , Pulmão/imunologia , Pulmão/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pneumonia/imunologia , Pneumonia/metabolismo , Pneumonia/microbiologia , Hipersensibilidade Respiratória/imunologia , Hipersensibilidade Respiratória/metabolismo , Hipersensibilidade Respiratória/microbiologia , Transdução de Sinais , Ésteres do Ácido Sulfúrico/administração & dosagem , Receptor 4 Toll-Like/metabolismo , Tirosina/administração & dosagemRESUMO
Proteins such as FUS phase separate to form liquid-like condensates that can harden into less dynamic structures. However, how these properties emerge from the collective interactions of many amino acids remains largely unknown. Here, we use extensive mutagenesis to identify a sequence-encoded molecular grammar underlying the driving forces of phase separation of proteins in the FUS family and test aspects of this grammar in cells. Phase separation is primarily governed by multivalent interactions among tyrosine residues from prion-like domains and arginine residues from RNA-binding domains, which are modulated by negatively charged residues. Glycine residues enhance the fluidity, whereas glutamine and serine residues promote hardening. We develop a model to show that the measured saturation concentrations of phase separation are inversely proportional to the product of the numbers of arginine and tyrosine residues. These results suggest it is possible to predict phase-separation properties based on amino acid sequences.
Assuntos
Proteína FUS de Ligação a RNA/genética , Proteínas de Ligação a RNA/fisiologia , Sequência de Aminoácidos , Aminoácidos/química , Animais , Arginina/química , Simulação por Computador , Células HeLa , Humanos , Proteínas Intrinsicamente Desordenadas/genética , Proteínas Intrinsicamente Desordenadas/fisiologia , Transição de Fase , Proteínas Priônicas/química , Proteínas Priônicas/genética , Príons/genética , Príons/fisiologia , Domínios Proteicos , Proteína FUS de Ligação a RNA/fisiologia , Proteínas de Ligação a RNA/isolamento & purificação , Células Sf9 , Tirosina/químicaRESUMO
Reversible phase separation underpins the role of FUS in ribonucleoprotein granules and other membrane-free organelles and is, in part, driven by the intrinsically disordered low-complexity (LC) domain of FUS. Here, we report that cooperative cation-π interactions between tyrosines in the LC domain and arginines in structured C-terminal domains also contribute to phase separation. These interactions are modulated by post-translational arginine methylation, wherein arginine hypomethylation strongly promotes phase separation and gelation. Indeed, significant hypomethylation, which occurs in FUS-associated frontotemporal lobar degeneration (FTLD), induces FUS condensation into stable intermolecular ß-sheet-rich hydrogels that disrupt RNP granule function and impair new protein synthesis in neuron terminals. We show that transportin acts as a physiological molecular chaperone of FUS in neuron terminals, reducing phase separation and gelation of methylated and hypomethylated FUS and rescuing protein synthesis. These results demonstrate how FUS condensation is physiologically regulated and how perturbations in these mechanisms can lead to disease.
Assuntos
Arginina/química , Chaperonas Moleculares/química , Proteína FUS de Ligação a RNA/química , Esclerose Lateral Amiotrófica/metabolismo , Animais , Cátions , Metilação de DNA , Demência Frontotemporal/metabolismo , Degeneração Lobar Frontotemporal/metabolismo , Humanos , Microscopia de Força Atômica , Microscopia de Fluorescência , Ligação Proteica , Domínios Proteicos , Processamento de Proteína Pós-Traducional , Estrutura Secundária de Proteína , Proteína FUS de Ligação a RNA/metabolismo , Tirosina/química , Xenopus laevisRESUMO
Self-non-self discrimination is central to T cell-mediated immunity. The kinetic proofreading model can explain T cell antigen receptor (TCR) ligand discrimination; however, the rate-limiting steps have not been identified. Here, we show that tyrosine phosphorylation of the T cell adapter protein LAT at position Y132 is a critical kinetic bottleneck for ligand discrimination. LAT phosphorylation at Y132, mediated by the kinase ZAP-70, leads to the recruitment and activation of phospholipase C-γ1 (PLC-γ1), an important effector molecule for T cell activation. The slow phosphorylation of Y132, relative to other phosphosites on LAT, is governed by a preceding glycine residue (G131) but can be accelerated by substituting this glycine with aspartate or glutamate. Acceleration of Y132 phosphorylation increases the speed and magnitude of PLC-γ1 activation and enhances T cell sensitivity to weaker stimuli, including weak agonists and self-peptides. These observations suggest that the slow phosphorylation of Y132 acts as a proofreading step to facilitate T cell ligand discrimination.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Ativação Linfocitária , Proteínas de Membrana/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Linfócitos T/imunologia , Proteínas Adaptadoras de Transdução de Sinal/imunologia , Animais , Feminino , Ligantes , Masculino , Proteínas de Membrana/imunologia , Camundongos , Fosfolipase C gama/metabolismo , Fosforilação/imunologia , Receptores de Antígenos de Linfócitos T/imunologia , Linfócitos T/metabolismo , Tirosina/metabolismo , Proteína-Tirosina Quinase ZAP-70/metabolismoRESUMO
The VEGF-A isoforms play a crucial role in vascular development, and the VEGF signaling pathway is a clinically validated therapeutic target for several pathological conditions. Alternative mRNA splicing leads to the generation of multiple VEGF-A isoforms, including VEGF165. A recent study reported the presence of another isoform, VEGF-Ax, arising from programmed readthrough translation. Compared to VEGF165, VEGF-Ax has a 22-amino-acid extension in the COOH terminus and has been reported to function as a negative regulator of VEGF signaling in endothelial cells, with potent anti-angiogenic effects. Here, we show that, contrary to the earlier report, VEGF-Ax stimulates endothelial cell mitogenesis, angiogenesis, as well as vascular permeability. Accordingly, VEGF-Ax induces phosphorylation of key tyrosine residues in VEGFR-2. Notably, VEGF-Ax was less potent than VEGF165, consistent with its impaired binding to the VEGF co-receptor neuropilin-1.
Assuntos
Neovascularização Fisiológica/fisiologia , Fator A de Crescimento do Endotélio Vascular , Processamento Alternativo , Sequência de Aminoácidos , Indutores da Angiogênese/farmacologia , Inibidores da Angiogênese/farmacologia , Animais , Permeabilidade Capilar/genética , Permeabilidade Capilar/fisiologia , Quimiotaxia/efeitos dos fármacos , Clonagem Molecular , Células Endoteliais/citologia , Células Endoteliais/efeitos dos fármacos , Células Endoteliais/fisiologia , Cobaias , Células HEK293 , Humanos , Camundongos , Mitógenos/farmacologia , Mitose/efeitos dos fármacos , Mitose/fisiologia , Neovascularização Fisiológica/efeitos dos fármacos , Neovascularização Fisiológica/genética , Neuropilina-1/metabolismo , Biossíntese de Proteínas , Isoformas de Proteínas/genética , Isoformas de Proteínas/metabolismo , Isoformas de Proteínas/farmacologia , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/farmacologia , Tirosina/metabolismo , Fator A de Crescimento do Endotélio Vascular/genética , Fator A de Crescimento do Endotélio Vascular/metabolismo , Fator A de Crescimento do Endotélio Vascular/farmacologia , Receptor 1 de Fatores de Crescimento do Endotélio Vascular/metabolismo , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismoRESUMO
To spread, transposons must integrate into target sites without disruption of essential genes while avoiding host defense systems. Tn7-like transposons employ multiple mechanisms for target-site selection, including protein-guided targeting and, in CRISPR-associated transposons (CASTs), RNA-guided targeting. Combining phylogenomic and structural analyses, we conducted a broad survey of target selectors, revealing diverse mechanisms used by Tn7 to recognize target sites, including previously uncharacterized target-selector proteins found in newly discovered transposable elements (TEs). We experimentally characterized a CAST I-D system and a Tn6022-like transposon that uses TnsF, which contains an inactivated tyrosine recombinase domain, to target the comM gene. Additionally, we identified a non-Tn7 transposon, Tsy, encoding a homolog of TnsF with an active tyrosine recombinase domain, which we show also inserts into comM. Our findings show that Tn7 transposons employ modular architecture and co-opt target selectors from various sources to optimize target selection and drive transposon spread.
Assuntos
Repetições Palindrômicas Curtas Agrupadas e Regularmente Espaçadas , Elementos de DNA Transponíveis , Plasmídeos , Elementos de DNA Transponíveis/genética , Recombinases/genética , Tirosina/genéticaRESUMO
Receptor protein tyrosine phosphatases (RPTPs) are involved in a broad list of cellular, developmental, and physiological functions. Altering their expression leads to significant changes in protein phosphorylation linked to a growing list of human diseases, including cancers and neurological disorders. In this issue of Genes & Development, Qian and colleagues (pp. 743-759) present the identification of a monoclonal antibody targeting PTPRD extracellular domain-inducing dimerization and inhibition of the phosphatase activities, causing the proteolysis of dimeric PTPRD by a mechanism involving intracellular degradation pathways. Their study supports the potential of modulating PTPRD via its extracellular domains. This opens a new framework in the clinical manipulation of PTPRD and its closely related family members.
Assuntos
Imunoglobulinas , Proteínas Tirosina Fosfatases , Humanos , Dimerização , Diferenciação Celular , Proteínas Tirosina Fosfatases/genética , TirosinaRESUMO
Many DNA and RNA regulatory proteins contain polypeptide domains that are unstructured when analyzed in cell lysates. These domains are typified by an over-representation of a limited number of amino acids and have been termed prion-like, intrinsically disordered or low-complexity (LC) domains. When incubated at high concentration, certain of these LC domains polymerize into labile, amyloid-like fibers. Here, we report methods allowing the generation of a molecular footprint of the polymeric state of the LC domain of hnRNPA2. By deploying this footprinting technique to probe the structure of the native hnRNPA2 protein present in isolated nuclei, we offer evidence that its LC domain exists in a similar conformation as that described for recombinant polymers of the protein. These observations favor biologic utility to the polymerization of LC domains in the pathway of information transfer from gene to message to protein.
Assuntos
Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/química , Sequência de Aminoácidos , Animais , Núcleo Celular/metabolismo , Ribonucleoproteínas Nucleares Heterogêneas Grupo A-B/metabolismo , Humanos , Dados de Sequência Molecular , Estrutura Terciária de Proteína , Proteínas Recombinantes/química , Schistosoma japonicum/enzimologia , Tirosina/análiseRESUMO
Spindle assembly required during mitosis depends on microtubule polymerization. We demonstrate that the evolutionarily conserved low-complexity protein, BuGZ, undergoes phase transition or coacervation to promote assembly of both spindles and their associated components. BuGZ forms temperature-dependent liquid droplets alone or on microtubules in physiological buffers. Coacervation in vitro or in spindle and spindle matrix depends on hydrophobic residues in BuGZ. BuGZ coacervation and its binding to microtubules and tubulin are required to promote assembly of spindle and spindle matrix in Xenopus egg extract and in mammalian cells. Since several previously identified spindle-associated components also contain low-complexity regions, we propose that coacervating proteins may be a hallmark of proteins that comprise a spindle matrix that functions to promote assembly of spindles by concentrating its building blocks.
Assuntos
Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Fuso Acromático/metabolismo , Animais , Células HeLa , Humanos , Mitose , Fenilalanina/metabolismo , Temperatura , Tubulina (Proteína)/metabolismo , Tirosina/metabolismo , XenopusRESUMO
Phosphorylation of proteins on tyrosine (Tyr) residues evolved in metazoan organisms as a mechanism of coordinating tissue growth1. Multicellular eukaryotes typically have more than 50 distinct protein Tyr kinases that catalyse the phosphorylation of thousands of Tyr residues throughout the proteome1-3. How a given Tyr kinase can phosphorylate a specific subset of proteins at unique Tyr sites is only partially understood4-7. Here we used combinatorial peptide arrays to profile the substrate sequence specificity of all human Tyr kinases. Globally, the Tyr kinases demonstrate considerable diversity in optimal patterns of residues surrounding the site of phosphorylation, revealing the functional organization of the human Tyr kinome by substrate motif preference. Using this information, Tyr kinases that are most compatible with phosphorylating any Tyr site can be identified. Analysis of mass spectrometry phosphoproteomic datasets using this compendium of kinase specificities accurately identifies specific Tyr kinases that are dysregulated in cells after stimulation with growth factors, treatment with anti-cancer drugs or expression of oncogenic variants. Furthermore, the topology of known Tyr signalling networks naturally emerged from a comparison of the sequence specificities of the Tyr kinases and the SH2 phosphotyrosine (pTyr)-binding domains. Finally we show that the intrinsic substrate specificity of Tyr kinases has remained fundamentally unchanged from worms to humans, suggesting that the fidelity between Tyr kinases and their protein substrate sequences has been maintained across hundreds of millions of years of evolution.
Assuntos
Fosfotirosina , Proteínas Tirosina Quinases , Especificidade por Substrato , Tirosina , Animais , Humanos , Motivos de Aminoácidos , Evolução Molecular , Espectrometria de Massas , Fosfoproteínas/química , Fosfoproteínas/metabolismo , Fosforilação , Fosfotirosina/metabolismo , Proteínas Tirosina Quinases/efeitos dos fármacos , Proteínas Tirosina Quinases/metabolismo , Proteoma/química , Proteoma/metabolismo , Proteômica , Transdução de Sinais , Domínios de Homologia de src , Tirosina/metabolismo , Tirosina/químicaRESUMO
Despite its disordered liquid-like structure, glass exhibits solid-like mechanical properties1. The formation of glassy material occurs by vitrification, preventing crystallization and promoting an amorphous structure2. Glass is fundamental in diverse fields of materials science, owing to its unique optical, chemical and mechanical properties as well as durability, versatility and environmental sustainability3. However, engineering a glassy material without compromising its properties is challenging4-6. Here we report the discovery of a supramolecular amorphous glass formed by the spontaneous self-organization of the short aromatic tripeptide YYY initiated by non-covalent cross-linking with structural water7,8. This system uniquely combines often contradictory sets of properties; it is highly rigid yet can undergo complete self-healing at room temperature. Moreover, the supramolecular glass is an extremely strong adhesive yet it is transparent in a wide spectral range from visible to mid-infrared. This exceptional set of characteristics is observed in a simple bioorganic peptide glass composed of natural amino acids, presenting a multi-functional material that could be highly advantageous for various applications in science and engineering.
Assuntos
Adesivos , Vidro , Oligopeptídeos , Adesivos/química , Vidro/química , Temperatura , Vitrificação , Água/química , Oligopeptídeos/química , Tirosina/química , Luz , Raios InfravermelhosRESUMO
AMPylation is a post-translational modification in which AMP is added to the amino acid side chains of proteins1,2. Here we show that, with ATP as the ligand and actin as the host activator, the effector protein LnaB of Legionella pneumophila exhibits AMPylase activity towards the phosphoryl group of phosphoribose on PRR42-Ub that is generated by the SidE family of effectors, and deubiquitinases DupA and DupB in an E1- and E2-independent ubiquitination process3-7. The product of LnaB is further hydrolysed by an ADP-ribosylhydrolase, MavL, to Ub, thereby preventing the accumulation of PRR42-Ub and ADPRR42-Ub and protecting canonical ubiquitination in host cells. LnaB represents a large family of AMPylases that adopt a common structural fold, distinct from those of the previously known AMPylases, and LnaB homologues are found in more than 20 species of bacterial pathogens. Moreover, LnaB also exhibits robust phosphoryl AMPylase activity towards phosphorylated residues and produces unique ADPylation modifications in proteins. During infection, LnaB AMPylates the conserved phosphorylated tyrosine residues in the activation loop of the Src family of kinases8,9, which dampens downstream phosphorylation signalling in the host. Structural studies reveal the actin-dependent activation and catalytic mechanisms of the LnaB family of AMPylases. This study identifies, to our knowledge, an unprecedented molecular regulation mechanism in bacterial pathogenesis and protein phosphorylation.
Assuntos
Monofosfato de Adenosina , Proteínas de Bactérias , Legionella pneumophila , Fosfotirosina , Transdução de Sinais , Humanos , Actinas/metabolismo , Monofosfato de Adenosina/metabolismo , Trifosfato de Adenosina/metabolismo , ADP-Ribosilação , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Hidrólise , Legionella pneumophila/enzimologia , Legionella pneumophila/metabolismo , Legionella pneumophila/patogenicidade , Ligantes , Modelos Moleculares , N-Glicosil Hidrolases/metabolismo , Fosforilação , Processamento de Proteína Pós-Traducional , Tirosina/metabolismo , Tirosina/química , Ubiquitina/metabolismo , Ubiquitinação , Enzimas Desubiquitinantes/metabolismo , Dobramento de Proteína , Fosfotirosina/química , Fosfotirosina/metabolismoRESUMO
Human feline leukaemia virus subgroup C receptor-related proteins 1 and 2 (FLVCR1 and FLVCR2) are members of the major facilitator superfamily1. Their dysfunction is linked to several clinical disorders, including PCARP, HSAN and Fowler syndrome2-7. Earlier studies concluded that FLVCR1 may function as a haem exporter8-12, whereas FLVCR2 was suggested to act as a haem importer13, yet conclusive biochemical and detailed molecular evidence remained elusive for the function of both transporters14-16. Here, we show that FLVCR1 and FLVCR2 facilitate the transport of choline and ethanolamine across the plasma membrane, using a concentration-driven substrate translocation process. Through structural and computational analyses, we have identified distinct conformational states of FLVCRs and unravelled the coordination chemistry underlying their substrate interactions. Fully conserved tryptophan and tyrosine residues form the binding pocket of both transporters and confer selectivity for choline and ethanolamine through cation-π interactions. Our findings clarify the mechanisms of choline and ethanolamine transport by FLVCR1 and FLVCR2, enhance our comprehension of disease-associated mutations that interfere with these vital processes and shed light on the conformational dynamics of these major facilitator superfamily proteins during the transport cycle.
Assuntos
Colina , Etanolamina , Proteínas de Membrana Transportadoras , Humanos , Sítios de Ligação , Transporte Biológico , Cátions/química , Cátions/metabolismo , Membrana Celular/metabolismo , Membrana Celular/química , Colina/metabolismo , Colina/química , Etanolamina/metabolismo , Etanolamina/química , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Membrana Transportadoras/química , Proteínas de Membrana Transportadoras/genética , Modelos Moleculares , Conformação Proteica , Receptores Virais/metabolismo , Receptores Virais/química , Especificidade por Substrato , Triptofano/metabolismo , Triptofano/química , Tirosina/metabolismo , Tirosina/química , MutaçãoRESUMO
Targeted radionuclide therapy, in which radiopharmaceuticals deliver potent radionuclides to tumours for localized irradiation, has addressed unmet clinical needs and improved outcomes for patients with cancer1-4. A therapeutic radiopharmaceutical must achieve both sustainable tumour targeting and fast clearance from healthy tissue, which remains a major challenge5,6. A targeted ligation strategy that selectively fixes the radiopharmaceutical to the target protein in the tumour would be an ideal solution. Here we installed a sulfur (VI) fluoride exchange (SuFEx) chemistry-based linker on radiopharmaceuticals to prevent excessively fast tumour clearance. When the engineered radiopharmaceutical binds to the tumour-specific protein, the system undergoes a binding-to-ligation transition and readily conjugates to the tyrosine residues through the 'click' SuFEx reaction. The application of this strategy to a fibroblast activation protein (FAP) inhibitor (FAPI) triggered more than 80% covalent binding to the protein and almost no dissociation for six days. In mice, SuFEx-engineered FAPI showed 257% greater tumour uptake than did the original FAPI, and increased tumour retention by 13-fold. The uptake in healthy tissues was rapidly cleared. In a pilot imaging study, this strategy identified more tumour lesions in patients with cancer than did other methods. SuFEx-engineered FAPI also successfully achieved targeted ß- and α-radionuclide therapy, causing nearly complete tumour regression in mice. Another SuFEx-engineered radioligand that targets prostate-specific membrane antigen (PSMA) also showed enhanced therapeutic efficacy. Considering the broad scope of proteins that can potentially be ligated to SuFEx warheads, it might be possible to adapt this strategy to other cancer targets.
Assuntos
Terapia de Alvo Molecular , Neoplasias da Próstata , Radioisótopos , Compostos Radiofarmacêuticos , Animais , Humanos , Masculino , Camundongos , Antígenos de Superfície/química , Antígenos de Superfície/metabolismo , Linhagem Celular Tumoral , Fluoretos/química , Fluoretos/metabolismo , Glutamato Carboxipeptidase II/química , Glutamato Carboxipeptidase II/metabolismo , Ligantes , Proteínas de Membrana/metabolismo , Proteínas de Membrana/química , Terapia de Alvo Molecular/métodos , Projetos Piloto , Neoplasias da Próstata/metabolismo , Neoplasias da Próstata/radioterapia , Radioisótopos/uso terapêutico , Compostos Radiofarmacêuticos/química , Compostos Radiofarmacêuticos/uso terapêutico , Compostos Radiofarmacêuticos/metabolismo , Compostos Radiofarmacêuticos/farmacocinética , Compostos de Enxofre/química , Compostos de Enxofre/metabolismo , Tirosina/metabolismo , Tirosina/química , Ensaios Antitumorais Modelo de XenoenxertoRESUMO
Photosystem II (PSII) catalyses the oxidation of water through a four-step cycle of Si states (i = 0-4) at the Mn4CaO5 cluster1-3, during which an extra oxygen (O6) is incorporated at the S3 state to form a possible dioxygen4-7. Structural changes of the metal cluster and its environment during the S-state transitions have been studied on the microsecond timescale. Here we use pump-probe serial femtosecond crystallography to reveal the structural dynamics of PSII from nanoseconds to milliseconds after illumination with one flash (1F) or two flashes (2F). YZ, a tyrosine residue that connects the reaction centre P680 and the Mn4CaO5 cluster, showed structural changes on a nanosecond timescale, as did its surrounding amino acid residues and water molecules, reflecting the fast transfer of electrons and protons after flash illumination. Notably, one water molecule emerged in the vicinity of Glu189 of the D1 subunit of PSII (D1-E189), and was bound to the Ca2+ ion on a sub-microsecond timescale after 2F illumination. This water molecule disappeared later with the concomitant increase of O6, suggesting that it is the origin of O6. We also observed concerted movements of water molecules in the O1, O4 and Cl-1 channels and their surrounding amino acid residues to complete the sequence of electron transfer, proton release and substrate water delivery. These results provide crucial insights into the structural dynamics of PSII during S-state transitions as well as O-O bond formation.
Assuntos
Oxigênio , Complexo de Proteína do Fotossistema II , Biocatálise/efeitos da radiação , Cálcio/metabolismo , Cristalografia , Transporte de Elétrons/efeitos da radiação , Elétrons , Manganês/metabolismo , Oxirredução/efeitos da radiação , Oxigênio/química , Oxigênio/metabolismo , Complexo de Proteína do Fotossistema II/química , Complexo de Proteína do Fotossistema II/metabolismo , Complexo de Proteína do Fotossistema II/efeitos da radiação , Prótons , Fatores de Tempo , Tirosina/metabolismo , Água/química , Água/metabolismoRESUMO
The recruitment of signaling proteins into activated receptor tyrosine kinases (RTKs) to produce rapid, high-fidelity downstream response is exposed to the ambiguity of random diffusion to the target site. Liquid-liquid phase separation (LLPS) overcomes this by providing elevated, localized concentrations of the required proteins while impeding competitor ligands. Here, we show a subset of phosphorylation-dependent RTK-mediated LLPS states. We then investigate the formation of phase-separated droplets comprising a ternary complex including the RTK, (FGFR2); the phosphatase, SHP2; and the phospholipase, PLCγ1, which assembles in response to receptor phosphorylation. SHP2 and activated PLCγ1 interact through their tandem SH2 domains via a previously undescribed interface. The complex of FGFR2 and SHP2 combines kinase and phosphatase activities to control the phosphorylation state of the assembly while providing a scaffold for active PLCγ1 to facilitate access to its plasma membrane substrate. Thus, LLPS modulates RTK signaling, with potential consequences for therapeutic intervention.
Assuntos
Proteína Tirosina Fosfatase não Receptora Tipo 11 , Transdução de Sinais , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 11/metabolismo , Tirosina/metabolismo , Domínios de Homologia de srcRESUMO
Human mixed-lineage leukemia (MLL) family methyltransferases methylate histone H3 lysine 4 to different methylation states (me1/me2/me3) with distinct functional outputs, but the mechanism underlying the different product specificities of MLL proteins remains unclear. Here, we develop methodologies to quantitatively measure the methylation rate difference between mono-, di-, and tri-methylation steps and demonstrate that MLL proteins possess distinct product specificities in the context of the minimum MLL-RBBP5-ASH2L complex. Comparative structural analyses of MLL complexes by X-ray crystal structures, fluorine-19 nuclear magnetic resonance, and molecular dynamics simulations reveal that the dynamics of two conserved tyrosine residues at the "F/Y (phenylalanine/tyrosine) switch" positions fine-tune the product specificity. The variation in the intramolecular interaction between SET-N and SET-C affects the F/Y switch dynamics, thus determining the product specificities of MLL proteins. These results indicate a modified F/Y switch rule applicable for most SET domain methyltransferases and implicate the functional divergence of MLL proteins.
Assuntos
Histona-Lisina N-Metiltransferase , Leucemia , Humanos , Histona-Lisina N-Metiltransferase/metabolismo , Histonas/metabolismo , Metiltransferases/genética , Metiltransferases/metabolismo , Lisina/metabolismo , Flúor/metabolismo , Proteína de Leucina Linfoide-Mieloide/metabolismo , Tirosina , FenilalaninaRESUMO
T cells reorganize their metabolic profiles after being activated, but the systemic metabolic effect of sustained activation of the immune system has remained unexplored. Here we report that augmented T cell responses in Pdcd1-/- mice, which lack the inhibitory receptor PD-1, induced a metabolic serum signature characterized by depletion of amino acids. We found that the depletion of amino acids in serum was due to the accumulation of amino acids in activated Pdcd1-/- T cells in the lymph nodes. A systemic decrease in tryptophan and tyrosine led to substantial deficiency in the neurotransmitters serotonin and dopamine in the brain, which resulted in behavioral changes dominated by anxiety-like behavior and exacerbated fear responses. Together these data indicate that excessive activation of T cells causes a systemic metabolomic shift with consequences that extend beyond the immune system.