RESUMO
We determined the structure of a complete, dimeric F1Fo-ATP synthase from yeast Yarrowia lipolytica mitochondria by a combination of cryo-EM and X-ray crystallography. The final structure resolves 58 of the 60 dimer subunits. Horizontal helices of subunit a in Fo wrap around the c-ring rotor, and a total of six vertical helices assigned to subunits a, b, f, i, and 8 span the membrane. Subunit 8 (A6L in human) is an evolutionary derivative of the bacterial b subunit. On the lumenal membrane surface, subunit f establishes direct contact between the two monomers. Comparison with a cryo-EM map of the F1Fo monomer identifies subunits e and g at the lateral dimer interface. They do not form dimer contacts but enable dimer formation by inducing a strong membrane curvature of â¼100°. Our structure explains the structural basis of cristae formation in mitochondria, a landmark signature of eukaryotic cell morphology.
Assuntos
Proteínas Fúngicas/química , Mitocôndrias/enzimologia , Membranas Mitocondriais/enzimologia , ATPases Mitocondriais Próton-Translocadoras/química , Yarrowia/enzimologia , Trifosfato de Adenosina/metabolismo , Catálise , Microscopia Crioeletrônica , Cristalografia por Raios X , Proteínas Fúngicas/metabolismo , Proteínas Fúngicas/ultraestrutura , Mitocôndrias/ultraestrutura , Membranas Mitocondriais/ultraestrutura , ATPases Mitocondriais Próton-Translocadoras/metabolismo , ATPases Mitocondriais Próton-Translocadoras/ultraestrutura , Modelos Moleculares , Conformação Proteica em alfa-Hélice , Multimerização Proteica , Subunidades Proteicas , Relação Estrutura-Atividade , Yarrowia/ultraestruturaRESUMO
Background: The Lewis (Le) blood group system, unlike most other blood groups, is not defined by antigens produced internally to the erythrocytes and their precursors but rather by glycan antigens adsorbed on to the erythrocyte membrane from the plasma. These oligosaccharides are synthesized by the two fucosyltransferases FUT2 and FUT3 mainly in epithelial cells of the digestive tract and transferred to the plasma. At their place of synthesis, some Lewis blood group carbohydrate antigen variants also seem to be involved in various gastrointestinal malignancies. However, relatively little is known about the transcriptional regulation of FUT2 and FUT3. Summary: To address this question, we screened existing literature and additionally used in silico prediction tools to identify novel candidate regulators for FUT2 and FUT3 and combine these findings with already known data on their regulation. With this approach, we were able to describe a variety of transcription factors, RNA binding proteins and microRNAs, which increase FUT2 and FUT3 transcription and translation upon interaction. Key Messages: Understanding the regulation of FUT2 and FUT3 is crucial to fully understand the blood group system Lewis (ISBT 007 LE) phenotypes, to shed light on the role of the different Lewis antigens in various pathologies, and to identify potential new diagnostic targets for these diseases.
The Lewis (Le) blood group system, in contrast to the majority of blood groups, is not able to synthesize its antigens itself. It depends on the attachment of different oligosaccharides to the erythrocyte membrane, which are adsorbed from the plasma. These glycans are modified by the fucosyltransferases 2 and 3 enzymes (FUT2/3). Beside their role in defining the Lewis blood group, FUT2 and FUT3 are also known to be involved in the susceptibility and progression of various gastrointestinal pathologies, like inflammatory bowel diseases (IBD) or colorectal cancer (CRC). Even though different expression levels of FUT2 and FUT3 have been described in these malignancies, relatively little is known about the mechanisms behind their transcriptional regulation. In this review, we aim to shed light on transcription factors (TFs) responsible for FUT2 and FUT3 expression as well as on post-transcriptional regulators by the means of RNA binding proteins (RBPs) and microRNAs (miRNAs). To achieve our goal, we combined previous knowledge on FUT2 and FUT3 expression regulation with a computational analysis to predict additional novel regulators. On this way, we are able to broaden our knowledge on FUT2 and FUT3 expression regulation and consequently might be able to transfer our findings into diagnostics or therapeutics in the future.
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The sarco(endo)plasmic reticulum Ca2+-ATPase (SERCA) is a P-type ATPase that transports Ca2+ from the cytosol into the sarco(endo)plasmic reticulum (SR/ER) lumen, driven by ATP. This primary transport activity depends on tight coupling between movements of the transmembrane helices forming the two Ca2+-binding sites and the cytosolic headpiece mediating ATP hydrolysis. We have addressed the molecular basis for this intramolecular communication by analyzing the structure and functional properties of the SERCA mutant E340A. The mutated Glu340 residue is strictly conserved among the P-type ATPase family of membrane transporters and is located at a seemingly strategic position at the interface between the phosphorylation domain and the cytosolic ends of 5 of SERCA's 10 transmembrane helices. The mutant displays a marked slowing of the Ca2+-binding kinetics, and its crystal structure in the presence of Ca2+ and ATP analog reveals a rotated headpiece, altered connectivity between the cytosolic domains, and an altered hydrogen bonding pattern around residue 340. Supported by molecular dynamics simulations, we conclude that the E340A mutation causes a stabilization of the Ca2+ sites in a more occluded state, hence displaying slowed dynamics. This finding underpins a crucial role of Glu340 in interdomain communication between the headpiece and the Ca2+-binding transmembrane region.
Assuntos
Proteínas de Ligação ao Cálcio/ultraestrutura , Cálcio/metabolismo , Conformação Proteica em alfa-Hélice , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/ultraestrutura , Trifosfato de Adenosina/química , Sequência de Aminoácidos/genética , Asparagina/química , Sítios de Ligação/genética , Cálcio/química , Sinalização do Cálcio/genética , Proteínas de Ligação ao Cálcio/química , Proteínas de Ligação ao Cálcio/genética , Cristalografia por Raios X , Citosol/metabolismo , Escherichia coli/enzimologia , Humanos , Ligação de Hidrogênio , Cinética , Simulação de Dinâmica Molecular , Mutação/genética , Fosforilação/genética , Domínios Proteicos/genética , Estrutura Secundária de Proteína , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Triptofano/químicaRESUMO
The contraction and relaxation of muscle cells is controlled by the successive rise and fall of cytosolic Ca(2+), initiated by the release of Ca(2+) from the sarcoplasmic reticulum and terminated by re-sequestration of Ca(2+) into the sarcoplasmic reticulum as the main mechanism of Ca(2+) removal. Re-sequestration requires active transport and is catalysed by the sarcoplasmic reticulum Ca(2+)-ATPase (SERCA), which has a key role in defining the contractile properties of skeletal and heart muscle tissue. The activity of SERCA is regulated by two small, homologous membrane proteins called phospholamban (PLB, also known as PLN) and sarcolipin (SLN). Detailed structural information explaining this regulatory mechanism has been lacking, and the structural features defining the pathway through which cytoplasmic Ca(2+) enters the intramembranous binding sites of SERCA have remained unknown. Here we report the crystal structure of rabbit SERCA1a (also known as ATP2A1) in complex with SLN at 3.1 Å resolution. The regulatory SLN traps the Ca(2+)-ATPase in a previously undescribed E1 state, with exposure of the Ca(2+) sites through an open cytoplasmic pathway stabilized by Mg(2+). The structure suggests a mechanism for selective Ca(2+) loading and activation of SERCA, and provides new insight into how SLN and PLB inhibition arises from stabilization of this E1 intermediate state without bound Ca(2+). These findings may prove useful in studying how autoinhibitory domains of other ion pumps modulate transport across biological membranes.
Assuntos
Cálcio/metabolismo , Citoplasma/metabolismo , Proteínas Musculares/metabolismo , Proteolipídeos/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Animais , Sítios de Ligação , Proteínas de Ligação ao Cálcio/química , Proteínas de Ligação ao Cálcio/metabolismo , Cristalografia por Raios X , Ativação Enzimática , Magnésio/metabolismo , Modelos Moleculares , Proteínas Musculares/química , Fosforilação , Ligação Proteica , Proteolipídeos/química , CoelhosRESUMO
The sarco(endo)plasmic reticulum Ca(2+)-ATPase (SERCA) couples ATP hydrolysis to transport of Ca(2+). This directed energy transfer requires cross-talk between the two Ca(2+) sites and the phosphorylation site over 50 Å distance. We have addressed the mechano-structural basis for this intramolecular signal by analysing the structure and the functional properties of SERCA mutant E309Q. Glu(309) contributes to Ca(2+) coordination at site II, and a consensus has been that E309Q only binds Ca(2+) at site I. The crystal structure of E309Q in the presence of Ca(2+) and an ATP analogue, however, reveals two occupied Ca(2+) sites of a non-catalytic Ca2E1 state. Ca(2+) is bound with micromolar affinity by both Ca(2+) sites in E309Q, but without cooperativity. The Ca(2+)-bound mutant does phosphorylate from ATP, but at a very low maximal rate. Phosphorylation depends on the correct positioning of the A-domain, requiring a shift of transmembrane segment M1 into an 'up and kinked position'. This transition is impaired in the E309Q mutant, most likely due to a lack of charge neutralization and altered hydrogen binding capacities at Ca(2+) site II.
Assuntos
Cálcio/metabolismo , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , Trifosfato de Adenosina/metabolismo , Catálise , Cristalografia por Raios X , Modelos Moleculares , Fosforilação , Conformação Proteica , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismoRESUMO
The Na(+)/K(+)-ATPase pumps three sodium ions out of and two potassium ions into the cell for each ATP molecule that is split, thereby generating the chemical and electrical gradients across the plasma membrane that are essential in, for example, signalling, secondary transport and volume regulation in animal cells. Crystal structures of the potassium-bound form of the pump revealed an intimate docking of the alpha-subunit carboxy terminus at the transmembrane domain. Here we show that this element is a key regulator of a previously unrecognized ion pathway. Current models of P-type ATPases operate with a single ion conduit through the pump, but our data suggest an additional pathway in the Na(+)/K(+)-ATPase between the ion-binding sites and the cytoplasm. The C-terminal pathway allows a cytoplasmic proton to enter and stabilize site III when empty in the potassium-bound state, and when potassium is released the proton will also return to the cytoplasm, thus allowing an overall asymmetric stoichiometry of the transported ions. The C terminus controls the gate to the pathway. Its structure is crucial for pump function, as demonstrated by at least eight mutations in the region that cause severe neurological diseases. This novel model for ion transport by the Na(+)/K(+)-ATPase is established by electrophysiological studies of C-terminal mutations in familial hemiplegic migraine 2 (FHM2) and is further substantiated by molecular dynamics simulations. A similar ion regulation is likely to apply to the H(+)/K(+)-ATPase and the Ca(2+)-ATPase.
Assuntos
Transporte de Íons , Enxaqueca com Aura/metabolismo , ATPase Trocadora de Sódio-Potássio/química , ATPase Trocadora de Sódio-Potássio/metabolismo , Animais , Cristalografia por Raios X , Humanos , Enxaqueca com Aura/genética , Modelos Moleculares , Simulação de Dinâmica Molecular , Oócitos/metabolismo , Potássio/metabolismo , Prótons , Squalus acanthias/metabolismo , Sus scrofa/metabolismo , XenopusRESUMO
Sarcolipin (SLN) is a regulatory peptide present in sarcoplasmic reticulum (SR) from skeletal muscle of animals. We find that native rabbit SLN is modified by a fatty acid anchor on Cys-9 with a palmitic acid in about 60% and, surprisingly, an oleic acid in the remaining 40%. SLN used for co-crystallization with SERCA1a (Winther, A. M., Bublitz, M., Karlsen, J. L., Moller, J. V., Hansen, J. B., Nissen, P., and Buch-Pedersen, M. J. (2013) Nature 495, 265-2691; Ref. 1) is also palmitoylated/oleoylated, but is not visible in crystal structures, probably due to disorder. Treatment with 1 m hydroxylamine for 1 h removes the fatty acids from a majority of the SLN pool. This treatment did not modify the SERCA1a affinity for Ca(2+) but increased the Ca(2+)-dependent ATPase activity of SR membranes indicating that the S-acylation of SLN or of other proteins is required for this effect on SERCA1a. Pig SLN is also fully palmitoylated/oleoylated on its Cys-9 residue, but in a reverse ratio of about 40/60. An alignment of 67 SLN sequences from the protein databases shows that 19 of them contain a cysteine and the rest a phenylalanine at position 9. Based on a cladogram, we postulate that the mutation from phenylalanine to cysteine in some species is the result of an evolutionary convergence. We suggest that, besides phosphorylation, S-acylation/deacylation also regulates SLN activity.
Assuntos
Cisteína/química , Proteínas Musculares/química , Músculo Esquelético/metabolismo , Ácido Oleico/química , Ácido Palmítico/química , Fenilalanina/química , Processamento de Proteína Pós-Traducional , Proteolipídeos/química , Sequência de Aminoácidos , Animais , Evolução Biológica , Cristalografia por Raios X , Cisteína/metabolismo , Expressão Gênica , Hidroxilamina/química , Cinética , Lipoilação , Modelos Moleculares , Dados de Sequência Molecular , Proteínas Musculares/classificação , Proteínas Musculares/genética , Proteínas Musculares/metabolismo , Músculo Esquelético/química , Ácido Oleico/metabolismo , Ácido Palmítico/metabolismo , Fenilalanina/metabolismo , Filogenia , Proteolipídeos/classificação , Proteolipídeos/genética , Proteolipídeos/metabolismo , Coelhos , Retículo Sarcoplasmático , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Alinhamento de Sequência , Especificidade da Espécie , Suínos , TermodinâmicaRESUMO
Proteins that contain metal cofactors are expected to be highly radiation sensitive since the degree of X-ray absorption correlates with the presence of high-atomic-number elements and X-ray energy. To explore the effects of local damage in serial femtosecond crystallography (SFX), Clostridium ferredoxin was used as a model system. The protein contains two [4Fe-4S] clusters that serve as sensitive probes for radiation-induced electronic and structural changes. High-dose room-temperature SFX datasets were collected at the Linac Coherent Light Source of ferredoxin microcrystals. Difference electron density maps calculated from high-dose SFX and synchrotron data show peaks at the iron positions of the clusters, indicative of decrease of atomic scattering factors due to ionization. The electron density of the two [4Fe-4S] clusters differs in the FEL data, but not in the synchrotron data. Since the clusters differ in their detailed architecture, this observation is suggestive of an influence of the molecular bonding and geometry on the atomic displacement dynamics following initial photoionization. The experiments are complemented by plasma code calculations.
Assuntos
Ferredoxinas/efeitos da radiação , Metaloproteínas/efeitos da radiação , Síncrotrons , Clostridium/efeitos da radiação , Cristalografia por Raios X/métodos , Relação Dose-Resposta à Radiação , Humanos , Modelos Moleculares , Lesões por Radiação , Sensibilidade e EspecificidadeRESUMO
The sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) is a transmembrane ion transporter belonging to the P(II)-type ATPase family. It performs the vital task of re-sequestering cytoplasmic Ca(2+) to the sarco/endoplasmic reticulum store, thereby also terminating Ca(2+)-induced signaling such as in muscle contraction. This minireview focuses on the transport pathways of Ca(2+) and H(+) ions across the lipid bilayer through SERCA. The ion-binding sites of SERCA are accessible from either the cytoplasm or the sarco/endoplasmic reticulum lumen, and the Ca(2+) entry and exit channels are both formed mainly by rearrangements of four N-terminal transmembrane α-helices. Recent improvements in the resolution of the crystal structures of rabbit SERCA1a have revealed a hydrated pathway in the C-terminal transmembrane region leading from the ion-binding sites to the cytosol. A comparison of different SERCA conformations reveals that this C-terminal pathway is exclusive to Ca(2+)-free E2 states, suggesting that it may play a functional role in proton release from the ion-binding sites. This is in agreement with molecular dynamics simulations and mutational studies and is in striking analogy to a similar pathway recently described for the related sodium pump. We therefore suggest a model for the ion exchange mechanism in P(II)-ATPases including not one, but two cytoplasmic pathways working in concert.
Assuntos
Cálcio/metabolismo , Prótons , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/química , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/metabolismo , Retículo Sarcoplasmático/metabolismo , Animais , Sítios de Ligação , Cálcio/química , Citosol/química , Citosol/metabolismo , Humanos , Transporte de Íons/fisiologia , Simulação de Dinâmica Molecular , Coelhos , Retículo Sarcoplasmático/química , Retículo Sarcoplasmático/genética , ATPases Transportadoras de Cálcio do Retículo Sarcoplasmático/genéticaRESUMO
The global spread of multidrug-resistant Acinetobacter baumannii infections urgently calls for the identification of novel drug targets. We solved the electron cryo-microscopy structure of the F1Fo-adenosine 5'-triphosphate (ATP) synthase from A. baumannii in three distinct conformational states. The nucleotide-converting F1 subcomplex reveals a specific self-inhibition mechanism, which supports a unidirectional ratchet mechanism to avoid wasteful ATP consumption. In the membrane-embedded Fo complex, the structure shows unique structural adaptations along both the entry and exit pathways of the proton-conducting a-subunit. These features, absent in mitochondrial ATP synthases, represent attractive targets for the development of next-generation therapeutics that can act directly at the culmination of bioenergetics in this clinically relevant pathogen.
Assuntos
Acinetobacter baumannii , Trifosfato de Adenosina/metabolismo , Microscopia CrioeletrônicaRESUMO
The fungal plasma membrane H+-ATPase Pma1 is a vital enzyme, generating a proton-motive force that drives the import of essential nutrients. Autoinhibited Pma1 hexamers in the plasma membrane of starving fungi are activated by glucose signaling and subsequent phosphorylation of the autoinhibitory domain. As related P-type adenosine triphosphatases (ATPases) are not known to oligomerize, the physiological relevance of Pma1 hexamers remained unknown. We have determined the structure of hexameric Pma1 from Neurospora crassa by electron cryo-microscopy at 3.3-Å resolution, elucidating the molecular basis for hexamer formation and autoinhibition and providing a basis for structure-based drug development. Coarse-grained molecular dynamics simulations in a lipid bilayer suggest lipid-mediated contacts between monomers and a substantial protein-induced membrane deformation that could act as a proton-attracting funnel.
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Peptide interactions with lipid bilayers play a key role in a range of biological processes and depend on electrostatic interactions between charged amino acids and lipid headgroups. Antimicrobial peptides (AMPs) initiate the killing of bacteria by binding to and destabilizing their membranes. The multiple peptide resistance factor (MprF) provides a defense mechanism for bacteria against a broad range of AMPs. MprF reduces the negative charge of bacterial membranes through enzymatic conversion of the anionic lipid phosphatidyl glycerol (PG) to either zwitterionic alanyl-phosphatidyl glycerol (Ala-PG) or cationic lysyl-phosphatidyl glycerol (Lys-PG). The resulting change in the membrane charge is suggested to reduce the binding of AMPs to membranes, thus impeding downstream AMP activity. Using coarse-grained molecular dynamics to investigate the effects of these modified lipids on AMP binding to model membranes, we show that AMPs have substantially reduced affinity for model membranes containing Ala-PG or Lys-PG. More than 5000 simulations in total are used to define the relationship between lipid bilayer composition, peptide sequence (using five different membrane-active peptides), and peptide binding to membranes. The degree of interaction of a peptide with a membrane correlates with the membrane surface charge density. Free energy profile (potential of mean force) calculations reveal that the lipid modifications due to MprF alter the energy barrier to peptide helix penetration of the bilayer. These results will offer a guide to the design of novel peptides, which addresses the issue of resistance via MprF-mediated membrane modification.
Assuntos
Lipídeos/química , Proteínas Citotóxicas Formadoras de Poros/química , Sequência de Aminoácidos , Membrana Celular/química , Bicamadas Lipídicas/química , Simulação de Dinâmica Molecular , Ligação Proteica , Eletricidade EstáticaRESUMO
During a bacterial infection, each successive step is orchestrated by a dedicated set of virulence factors. In Gram-positive bacteria, the presentation or release of such factors is crucially dependent on the continual remodelling of the cell wall. We have investigated the autolysin or peptidoglycan hydrolase Auto (Lmo1076) from the human pathogen Listeria monocytogenes to structurally and biochemically underpin its role in host cell invasion. We demonstrate that Auto is an N-acetylglucosaminidase, that it is autoinhibited when newly secreted but activated by proteolytic cleavage, that it has an acidic pH optimum and that it preferentially cleaves acetylated over de-acetylated peptidoglycan. The crystal structure of Auto, the first for glycoside hydrolase family 73, and the first for a listerial autolysin, indicates that autoinhibition is due to an N-terminal alpha-helix unique to Auto that physically blocks the substrate-binding cleft. We identify Glu122 and Glu156 as the two catalytically essential carboxylate groups. The physical properties of Auto as well as its localization to lipoteichoic acid by its four C-terminal GW modules imply cell wall degradation by Auto to be highly co-ordinated. Its spatio-temporally controlled activation and localized activity in an acidified environment indicate that it facilitates remodelling of the cell wall and may be involved in co-ordinating the release of virulence factors at specific stages of an infection.
Assuntos
Proteínas de Bactérias/metabolismo , Listeria monocytogenes/enzimologia , Proteínas de Membrana/metabolismo , N-Acetil-Muramil-L-Alanina Amidase/metabolismo , Proteínas de Bactérias/genética , Domínio Catalítico , Parede Celular/metabolismo , Clonagem Molecular , Precursores Enzimáticos/genética , Precursores Enzimáticos/metabolismo , Concentração de Íons de Hidrogênio , Lipopolissacarídeos/metabolismo , Listeria monocytogenes/genética , Listeria monocytogenes/patogenicidade , Proteínas de Membrana/genética , Mutagênese Sítio-Dirigida , N-Acetil-Muramil-L-Alanina Amidase/genética , Estrutura Terciária de Proteína , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Ácidos Teicoicos/metabolismo , VirulênciaRESUMO
The structure determination of soluble and membrane proteins can be hindered by the crystallographic phase problem, especially in the absence of a suitable homologous structure. Experimental phasing is the method of choice for novel structures; however, it often requires heavy-atom derivatization, which can be difficult and time-consuming. Here, a novel and rapid method to obtain experimental phases for protein structure determination by vanadium phasing is reported. Vanadate is a transition-state mimic of phosphoryl-transfer reactions and it has the advantage of binding specifically to the active site of numerous enzymes catalyzing this reaction. The applicability of vanadium phasing has been validated by determining the structures of three different protein-vanadium complexes, two of which are integral membrane proteins: the rabbit sarcoplasmic reticulum Ca2+-ATPase, the antibacterial peptide ATP-binding cassette transporter McjD from Escherichia coli and the soluble enzyme RNAse A from Bos taurus. Vanadium phasing was successful even at low resolution and despite severe anisotropy in the data. This method is principally applicable to a large number of proteins, representing six of the seven Enzyme Commission classes. It relies exclusively on the specific chemistry of the protein and it does not require any modifications, making it a very powerful addition to the phasing toolkit. In addition to the phasing power of this technique, the protein-vanadium complexes also provide detailed insights into the reaction mechanisms of the studied proteins.
RESUMO
The identification of SERCA (sarco/endoplasmic reticulum calcium ATPase) as a target for modulating gain-of-function NOTCH1 mutations in Notch-dependent cancers has spurred the development of this compound class for cancer therapeutics. Despite the innate toxicity challenge associated with SERCA inhibition, we identified CAD204520, a small molecule with better drug-like properties and reduced off-target Ca2+ toxicity compared with the SERCA inhibitor thapsigargin. In this work, we describe the properties and complex structure of CAD204520 and show that CAD204520 preferentially targets mutated over wild-type NOTCH1 proteins in T cell acute lymphoblastic leukemia (T-ALL) and mantle cell lymphoma (MCL). Uniquely among SERCA inhibitors, CAD204520 suppresses NOTCH1-mutated leukemic cells in a T-ALL xenografted model without causing cardiac toxicity. This study supports the development of SERCA inhibitors for Notch-dependent cancers and extends their application to cases with isolated mutations in the PEST degradation domain of NOTCH1, such as MCL or chronic lymphocytic leukemia (CLL).
Assuntos
Antineoplásicos/farmacologia , Inibidores Enzimáticos/farmacologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/tratamento farmacológico , Receptor Notch1/antagonistas & inibidores , Animais , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Inibidores Enzimáticos/síntese química , Inibidores Enzimáticos/química , Feminino , Humanos , Masculino , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos ICR , Camundongos Endogâmicos NOD , Camundongos SCID , Estrutura Molecular , Mutação , Neoplasias Experimentais/tratamento farmacológico , Neoplasias Experimentais/metabolismo , Neoplasias Experimentais/patologia , Leucemia-Linfoma Linfoblástico de Células T Precursoras/metabolismo , Leucemia-Linfoma Linfoblástico de Células T Precursoras/patologia , Receptor Notch1/genética , Receptor Notch1/metabolismo , Transdução de Sinais/efeitos dos fármacosRESUMO
We have identified a series of tetrahydrocarbazoles as novel P-type ATPase inhibitors. Using a set of rationally designed analogues, we have analyzed their structure-activity relationship using functional assays, crystallographic data and computational modeling. We found that tetrahydrocarbazoles inhibit adenosine triphosphate (ATP) hydrolysis of the fungal H+-ATPase, depolarize the fungal plasma membrane and exhibit broad-spectrum antifungal activity. Comparative inhibition studies indicate that many tetrahydrocarbazoles also inhibit the mammalian Ca2+-ATPase (SERCA) and Na+,K+-ATPase with an even higher potency than Pma1. We have located the binding site for this compound class by crystallographic structure determination of a SERCA-tetrahydrocarbazole complex to 3.0 Å resolution, finding that the compound binds to a region above the ion inlet channel of the ATPase. A homology model of the Candida albicans H+-ATPase based on this crystal structure, indicates that the compounds could bind to the same pocket and identifies pocket extensions that could be exploited for selectivity enhancement. The results of this study will aid further optimization towards selective H+-ATPase inhibitors as a new class of antifungal agents.
Assuntos
Antifúngicos/farmacologia , Carbazóis/farmacologia , Inibidores Enzimáticos/farmacologia , ATPases do Tipo-P/antagonistas & inibidores , Trifosfato de Adenosina/metabolismo , Antifúngicos/química , Candida/efeitos dos fármacos , Carbazóis/química , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Inibidores Enzimáticos/química , Células Hep G2 , Humanos , Hidrólise , Potenciais da Membrana/efeitos dos fármacos , Testes de Sensibilidade Microbiana , Modelos Moleculares , Estrutura Molecular , ATPases do Tipo-P/química , Saccharomyces cerevisiae/efeitos dos fármacosRESUMO
In the past 15 years, a large body of structural information on P-type ATPases has accumulated in the Protein Data Bank. The available crystal structures cover different enzymes in a variety of conformational states that are associated with the enzymatic activity of ATP-dependent ion translocation across membranes. This chapter provides an overview about the available structural information, along with some practical instructions on how to make meaningful comparisons of structures in different conformations, and how to generate morphs between series of structures, in order to analyze domain movements and structural flexibility.
Assuntos
Adenosina Trifosfatases/química , Biologia Computacional/métodos , Adenosina Trifosfatases/metabolismo , Biocatálise , Cristalografia por Raios X , Bases de Dados de Proteínas , Elétrons , Estabilidade Enzimática , Modelos Moleculares , Conformação ProteicaRESUMO
Vanadate is the hallmark inhibitor of the P-type ATPase family; however, structural details of its inhibitory mechanism have remained unresolved. We have determined the crystal structure of sarcoplasmic reticulum Ca(2+)-ATPase with bound vanadate in the absence of Ca(2+). Vanadate is bound at the catalytic site as a planar VO3(-) in complex with water and Mg(2+) in a dephosphorylation transition-state-like conformation. Validating bound VO3(-) by anomalous difference Fourier maps using long-wavelength data we also identify a hitherto undescribed Cl(-) site near the dephosphorylation site. Crystallization was facilitated by trinitrophenyl (TNP)-derivatized nucleotides that bind with the TNP moiety occupying the binding pocket that normally accommodates the adenine of ATP, rationalizing their remarkably high affinity for E2P-like conformations of the Ca(2+)-ATPase. A comparison of the configurations of bound nucleotide analogs in the E2·VO3(-) structure with that in E2·BeF3(-) (E2P ground state analog) reveals multiple binding modes to the Ca(2+)-ATPase.