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1.
J Chem Phys ; 151(12): 124104, 2019 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-31575184

RESUMO

An interfacial regularized Stokeslet scheme is presented to predict the motion of solid bodies (e.g., proteins or gel-phase domains) embedded within flowing lipid bilayer membranes. The approach provides a numerical route to calculate velocities and angular velocities in complex flow fields that are not amenable to simple Faxén-like approximations. Additionally, when applied to shearing motions, the calculations yield predictions for the effective surface viscosity of dilute rigid-body-laden membranes. In the case of cylindrical proteins, effective viscosity calculations are compared to two prior analytical predictions from the literature. Effective viscosity predictions for a dilute suspension of rod-shaped objects in the membrane are also presented.


Assuntos
Bicamadas Lipídicas/química , Modelos Químicos , Fenômenos Biomecânicos , Proteínas de Membrana/química , Torque , Viscosidade
2.
Phys Chem Chem Phys ; 21(36): 20239-20251, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31490518

RESUMO

The amyloid formation of human islet amyloid polypeptide (hIAPP)-an intrinsically disordered peptide, is associated with type II diabetes. Cellular membranes, especially those composed of negatively-charged lipids, accelerate the hIAPP amyloid fibrillation, and their integrity is disrupted during the aggregation process, leading to cell apoptosis. However, the underlying molecular mechanism is not well understood. Herein, we investigated the conformational dynamics during the interactions of hIAPP monomer with POPG membrane bilayer, by carrying out µs-long all-atom molecular dynamics simulations. Starting from the metastable coiled conformations in water, hIAPP monomers tend to adopt transient α-helical and ß-sheet structures when adsorbing to the membrane surface. The amphiphilic N-terminal region further inserts into the membrane interior and is located at the lipid head-tail interface, mainly in turn and α-helical structures. In contrast, the ß-hairpin structures reside on the membrane surface without insertion, and expand laterally with the hydrophobic residues exposed to the solvent. Moreover, the adsorption and insertion of hIAPP monomers induce two distinct local membrane deformations: (1) the hIAPP adsorption on the membrane surface mainly causes membrane bending; (2) the insertion of both turns and α-helices synchronizes with the formation of hydrophobic defects on the POPG membrane, leading to stronger membrane stretching and a longer coherence length of membrane thinning. Based on the structural and dynamical results, we propose that ß-hairpin structures may be a precursor for the fibrillation on the membrane surface due to the flat geometry and hydrophobic regions exposed to solvent, while N-terminal amphiphilic α-helices would facilitate hIAPP assembling into toxic oligomers inside the membrane.


Assuntos
Membrana Celular/química , Polipeptídeo Amiloide das Ilhotas Pancreáticas/química , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Humanos , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo
3.
Comput Biol Chem ; 81: 9-15, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31472418

RESUMO

Position-Specific Scoring Matrix (PSSM) is an excellent feature extraction method that was proposed early in protein classifying prediction, but within the restriction of feature shape in PSSM, researchers make a lot attempts to process it so that PSSM can be input to the traditional machine learning algorithms. These processes drop information provided by PSSM in a way thus the feature representation is limited. Moreover, the high-dimensional feature representation of PSSM makes it incompatible with other feature extraction methods. We use the PSSM as the input of Recurrent Neural Network without any post-processing, the amino acids in protein sequences are regarded as time step in RNN. This way takes full advantage of the information that PSSM provides. In this study, the PSSM is input to the model directly and the internal information of PSSM is fully utilized, we propose an end-to-end solution and achieve state-of-the-art performance. Ultimately, the exploration of how to combine PSSM with traditional feature extraction methods is carried out and achieve slightly improved performance. Our network architecture is implemented in Python and is available at https://github.com/YellowcardD/RNN-for-membrane-protein-types-prediction.


Assuntos
Proteínas de Membrana/classificação , Redes Neurais (Computação) , Matrizes de Pontuação de Posição Específica , Biologia Computacional/métodos , Bases de Dados de Proteínas/estatística & dados numéricos , Proteínas de Membrana/química
4.
Phys Chem Chem Phys ; 21(34): 18422-18457, 2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31410425

RESUMO

Our review addresses how material properties emerge from atomistic-level interactions in the case of lipid membrane nanostructures. We summarize advances in solid-state nuclear magnetic resonance (NMR) spectroscopy in conjunction with alternative small-angle X-ray and neutron scattering methods for investigating lipid flexibility and dynamics. Solid-state 2H NMR is advantageous in that it provides atomistically resolved information about the order parameters and mobility of phospholipids within liquid-crystalline membranes. Bilayer deformation in response to external perturbations occurs over a range of length scales and allows one to disentangle how the bulk material properties emerge from atomistic forces. Examples include structural parameters such as the area per lipid and volumetric thickness together with the moduli for elastic deformation. Membranes under osmotic stress allow one to further distinguish collective undulations and quasielastic contributions from short-range noncollective effects. Our approach reveals how membrane elasticity involves length scales ranging from the bilayer dimensions on down to the size of the flexible lipid segments. Collective lipid interactions of the order of the bilayer thickness and less occur in the liquid-crystalline state. Emergence of lipid material properties is significant for models of lipid-protein forces acting on the mesoscopic length scale that play key roles in biomembrane functions.


Assuntos
Bicamadas Lipídicas/química , Espectroscopia de Ressonância Magnética/métodos , Nanoestruturas/química , Fosfolipídeos/química , Membrana Celular/química , Elasticidade , Cristais Líquidos/química , Proteínas de Membrana/química , Modelos Químicos , Nêutrons , Pressão Osmótica , Espalhamento de Radiação , Termodinâmica , Raios X
5.
J Chem Theory Comput ; 15(8): 4673-4686, 2019 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-31265271

RESUMO

The time step of atomistic molecular dynamics (MD) simulations is determined by the fastest motions in the system and is typically limited to 2 fs. An increasingly popular approach is to increase the mass of the hydrogen atoms to ∼3 amu and decrease the mass of the parent atom by an equivalent amount. This approach, known as hydrogen-mass repartitioning (HMR), permits time steps up to 4 fs with reasonable simulation stability. While HMR has been applied in many published studies to date, it has not been extensively tested for membrane-containing systems. Here, we compare the results of simulations of a variety of membranes and membrane-protein systems run using a 2 fs time step and a 4 fs time step with HMR. For pure membrane systems, we find almost no difference in structural properties, such as area-per-lipid, electron density profiles, and order parameters, although there are differences in kinetic properties such as the diffusion constant. Conductance through a porin in an applied field, partitioning of a small peptide, hydrogen-bond dynamics, and membrane mixing show very little dependence on HMR and the time step. We also tested a 9 Å cutoff as compared to the standard CHARMM cutoff of 12 Å, finding significant deviations in many properties tested. We conclude that HMR is a valid approach for membrane systems, but a 9 Å cutoff is not.


Assuntos
Membrana Celular/química , Hidrogênio/química , Bicamadas Lipídicas/química , Proteínas de Membrana/química , Simulação de Dinâmica Molecular , Difusão , Glicoforina/química , Humanos , Movimento (Física) , Peptídeos/química , Fosfatidilcolinas/química , Multimerização Proteica , Receptores Acoplados a Proteínas-G/química , Termodinâmica
6.
Anal Chim Acta ; 1076: 32-47, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31203962

RESUMO

Electroactive microorganisms possess the unique ability to transfer electrons to or from solid phase electron conductors, e.g., electrodes or minerals, through various physiological mechanisms. The processes are commonly known as extracellular electron transfer and broadly harnessed in microbial electrochemical systems, such as microbial biosensors, microbial electrosynthesis, or microbial fuel cells. Apart from a few model microorganisms, the nature of the microbe-electrode conductive interaction is poorly understood for most of the electroactive species. The interaction determines the efficiency and a potential scaling up of bioelectrochemical systems. Gram-positive bacteria generally have a thick electron non-conductive cell wall and are believed to exhibit weak extracellular electron shuttling activity. This review highlights reported research accomplishments on electroactive Gram-positive bacteria. The use of electron-conducting polymers as mediators is considered as one promising strategy to enhance the electron transfer efficiency up to application scale. In view of the recent progress in understanding the molecular aspects of the extracellular electron transfer mechanisms of Enterococcus faecalis, the electron transfer properties of this bacterium are especially focused on. Fundamental knowledge on the nature of microbial extracellular electron transfer and its possibilities can provide insight in interspecies electron transfer and biogeochemical cycling of elements in nature. Additionally, a comprehensive understanding of cell-electrode interactions may help in overcoming insufficient electron transfer and restricted operational performance of various bioelectrochemical systems and facilitate their practical applications.


Assuntos
Elétrons , Bactérias Gram-Positivas/química , Parede Celular/química , Eletrodos , Hidrogéis/química , Proteínas de Membrana/química , Oxirredução , Polímeros/química
7.
Subcell Biochem ; 92: 187-219, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31214988

RESUMO

Signal peptidases are the membrane bound enzymes that cleave off the amino-terminal signal peptide from secretory preproteins . There are two types of bacterial signal peptidases . Type I signal peptidase utilizes a serine/lysine catalytic dyad mechanism and is the major signal peptidase in most bacteria. Type II signal peptidase is an aspartic protease specific for prolipoproteins. This chapter will review what is known about the structure, function and mechanism of these unique enzymes.


Assuntos
Ácido Aspártico Endopeptidases/química , Ácido Aspártico Endopeptidases/metabolismo , Bactérias/enzimologia , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Serina Endopeptidases/química , Serina Endopeptidases/metabolismo
8.
Subcell Biochem ; 92: 301-335, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31214991

RESUMO

The invention of a biological membrane which is used as energy storage system to drive the metabolism of a primordial, unicellular organism represents a key event in the evolution of life. The innovative, underlying principle of this key event is respiration. In respiration, a lipid bilayer with insulating properties is chosen as the site for catalysis of an exergonic redox reaction converting substrates offered from the environment, using the liberated Gibbs free energy (ΔG) for the build-up of an electrochemical H+ (proton motive force, PMF) or Na+ gradient (sodium motive force, SMF) across the lipid bilayer. Very frequently , several redox reactions are performed in a consecutive manner, with the first reaction delivering a product which is used as substrate for the second redox reaction, resulting in a respiratory chain. From today's perspective, the (mostly) unicellular bacteria and archaea seem to be much simpler and less evolved when compared to multicellular eukaryotes. However, they are overwhelmingly complex with regard to the various respiratory chains which permit survival in very different habitats of our planet, utilizing a plethora of substances to drive metabolism. This includes nitrogen, sulfur and carbon compounds which are oxidized or reduced by specialized, respiratory enzymes of bacteria and archaea which lie at the heart of the geochemical N, S and C-cycles. This chapter gives an overview of general principles of microbial respiration considering thermodynamic aspects, chemical reactions and kinetic restraints. The respiratory chains of Escherichia coli and Vibrio cholerae are discussed as models for PMF- versus SMF-generating processes, respectively. We introduce main redox cofactors of microbial respiratory enzymes, and the concept of intra-and interelectron transfer. Since oxygen is an electron acceptor used by many respiratory chains, the formation and removal of toxic oxygen radicals is described. Promising directions of future research are respiratory enzymes as novel bacterial targets, and biotechnological applications relying on respiratory complexes.


Assuntos
Archaea/metabolismo , Bactérias/metabolismo , Membrana Celular/metabolismo , Transporte de Elétrons , Metabolismo Energético , Proteínas de Membrana/química , Proteínas de Membrana/metabolismo , Archaea/citologia , Archaea/enzimologia , Bactérias/citologia , Bactérias/enzimologia
9.
Nat Plants ; 5(6): 626-636, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31182847

RESUMO

In plants and green algae, the core of photosystem I (PSI) is surrounded by a peripheral antenna system consisting of light-harvesting complex I (LHCI). Here we report the cryo-electron microscopic structure of the PSI-LHCI supercomplex from the green alga Chlamydomonas reinhardtii. The structure reveals that eight Lhca proteins form two tetrameric LHCI belts attached to the PsaF side while the other two Lhca proteins form an additional Lhca2/Lhca9 heterodimer attached to the opposite side. The spatial arrangement of light-harvesting pigments reveals that Chlorophylls b are more abundant in the outer LHCI belt than in the inner LHCI belt and are absent from the core, thereby providing the downhill energy transfer pathways to the PSI core. PSI-LHCI is complexed with a plastocyanin on the patch of lysine residues of PsaF at the luminal side. The assembly provides a structural basis for understanding the mechanism of light-harvesting, excitation energy transfer of the PSI-LHCI supercomplex and electron transfer with plastocyanin.


Assuntos
Chlamydomonas reinhardtii/ultraestrutura , Complexos de Proteínas Captadores de Luz/ultraestrutura , Complexo de Proteína do Fotossistema I/química , Complexo de Proteína do Fotossistema I/ultraestrutura , Transferência de Energia , Proteínas de Membrana/química , Modelos Moleculares , Plastocianina/química , Conformação Proteica , Especificidade da Espécie
10.
Chemistry ; 25(49): 11545-11554, 2019 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-31243822

RESUMO

Amphipathic agents are widely used in various fields including biomedical sciences. Micelle-forming detergents are particularly useful for in vitro membrane-protein characterization. As many conventional detergents are limited in their ability to stabilize membrane proteins, it is necessary to develop novel detergents to facilitate membrane-protein research. In the current study, we developed novel trimaltoside detergents with an alkyl pendant-bearing terphenyl unit as a hydrophobic group, designated terphenyl-cored maltosides (TPMs). We found that the geometry of the detergent hydrophobic group substantially impacts detergent self-assembly behavior, as well as detergent efficacy for membrane-protein stabilization. TPM-Vs, with a bent terphenyl group, were superior to the linear counterparts (TPM-Ls) at stabilizing multiple membrane proteins. The favorable protein stabilization efficacy of these bent TPMs is likely associated with a binding mode with membrane proteins distinct from conventional detergents and facial amphiphiles. When compared to n-dodecyl-ß-d-maltoside (DDM), most TPMs were superior or comparable to this gold standard detergent at stabilizing membrane proteins. Notably, TPM-L3 was particularly effective at stabilizing the human ß2 adrenergic receptor (ß2 AR), a G-protein coupled receptor, and its complex with Gs protein. Thus, the current study not only provides novel detergent tools that are useful for membrane-protein study, but also suggests a critical role for detergent hydrophobic group geometry in governing detergent efficacy.


Assuntos
Detergentes/química , Maltose/química , Proteínas de Membrana/química , Materiais Biomiméticos/química , Interações Hidrofóbicas e Hidrofílicas , Micelas , Conformação Molecular , Estabilidade Proteica , Solubilidade , Compostos de Terfenil/química
11.
J Phys Chem Lett ; 10(14): 3972-3977, 2019 Jul 18.
Artigo em Inglês | MEDLINE | ID: mdl-31246477

RESUMO

Membrane-binding interfaces of peripheral proteins are restricted to a small part of their exposed surface, so the ability to engage in strong selective interactions with membrane lipids at various depths in the interface, both below and above the phosphates, is an advantage. Driven by their hydrophobicity, aromatic amino acids preferentially partition into membrane interfaces, often below the phosphates, yet enthalpically favorable interactions with the lipid headgroups, above the phosphate plane, are likely to further stabilize high interfacial positions. Using free-energy perturbation, we calculate the energetic cost of alanine substitution for 11 interfacial aromatic amino acids from 3 peripheral proteins. We show that the involvement in cation-π interactions with the headgroups (i) increases the ΔΔGtransfer as compared with insertion at the same depth without cation-π stabilization and (ii) can contribute at least as much as deeper insertion below the phosphates, highlighting the multiple roles of aromatics in peripheral membrane protein affinity.


Assuntos
Aminoácidos Aromáticos/química , Colina/química , Lipídeos/química , Proteínas de Membrana/química , Fosfatos/química , Cátions/química , Modelos Moleculares , Termodinâmica
12.
Adv Exp Med Biol ; 1135: 3-25, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31098808

RESUMO

The impact of cholesterol on the structure and function of membrane proteins was recognized several decades ago, but the molecular mechanisms underlying these effects have remained elusive. There appear to be multiple mechanisms by which cholesterol interacts with proteins. A complete understanding of cholesterol-sensing motifs is still undergoing refinement. Initially, cholesterol was thought to exert only non-specific effects on membrane fluidity. It was later shown that this lipid could specifically interact with membrane proteins and affect both their structure and function. In this article, we have summarized and critically analyzed our evolving understanding of the affinity, specificity and stereoselectivity of the interactions of cholesterol with membrane proteins. We review the different computational approaches that are currently used to identify cholesterol binding sites in membrane proteins and the biochemical logic that governs each type of site, including CRAC, CARC, SSD and amphipathic helix motifs. There are physiological implications of these cholesterol-recognition motifs for G-protein coupled receptors (GPCR) and ion channels, in membrane trafficking and membrane fusion (SNARE) proteins. There are also pathological implications of cholesterol binding to proteins involved in neurological disorders (Alzheimer, Parkinson, Creutzfeldt-Jakob) and HIV fusion. In each case, our discussion is focused on the key molecular aspects of the cholesterol and amino acid motifs in membrane-embedded regions of membrane proteins that define the physiologically relevant crosstalk between the two. Our understanding of the factors that determine if these motifs are functional in cholesterol binding will allow us enhanced predictive capabilities.


Assuntos
Motivos de Aminoácidos , Colesterol/química , Proteínas de Membrana/química , Transporte Biológico , Humanos , Ligação Proteica , Receptores Acoplados a Proteínas-G/química , Proteínas SNARE/química
13.
Adv Exp Med Biol ; 1135: 67-86, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31098811

RESUMO

Cholesterol is a highly asymmetric lipid molecule. As an essential constituent of the cell membrane, cholesterol plays important structural and signaling roles in various biological processes. The first high-resolution crystal structure of a transmembrane protein in complex with cholesterol was a human ß2-adrenergic receptor structure deposited to the Protein Data Bank in 2007. Since then, the number of the cholesterol-bound crystal structures has grown considerably providing an invaluable resource for obtaining insights into the structural characteristics of cholesterol binding. In this work, we examine the spatial and orientation distributions of cholesterol relative to the protein framework in a collection of 73 crystal structures of membrane proteins. To characterize the cholesterol-protein interactions, we apply singular value decomposition to an array of interatomic distances, which allows us to systematically assess the flexibility and variability of cholesterols in transmembrane proteins. Together, this joint analysis reveals the common characteristics among the observed cholesterol structures, thereby offering important guidelines for prediction and modification of potential cholesterol binding sites in transmembrane proteins.


Assuntos
Colesterol/química , Proteínas de Membrana/química , Sítios de Ligação , Membrana Celular , Humanos , Ligação Proteica , Receptores Adrenérgicos beta 2/química
14.
Nanomedicine (Lond) ; 14(10): 1231-1246, 2019 05.
Artigo em Inglês | MEDLINE | ID: mdl-31124759

RESUMO

Aim: Nanomaterials and nanomedicinal products tend to interfere with various commonly used assays, including regulatory required endotoxin detection methods for medicines. We developed a method to quantify endotoxin levels that is compatible with nanomaterials and nanomedicinal products. Materials & methods: The method is based on measuring endotoxin indirectly via 3-hydroxylated fatty acids of lipid-A, using Ultra High Performance Liquid Chromatography coupled with mass spectrometry. The outcome was related to results of the commonly used Limulus Amebocyte Lysate method. Results: The ultra high performance liquid chromatography coupled with mass spectrometry method has clear advantages compared with other endotoxin determination assays; particularly the absence of nanospecific interference. Conclusion: The method is sensitive, straightforward and accurate in determining and quantifying endotoxin in nanomedicinal product samples.


Assuntos
Lipopolissacarídeos/análise , Nanoestruturas/química , Bioensaio , Cério/química , Cromatografia Líquida de Alta Pressão , Dendrímeros/química , Ácidos Graxos/análise , Compostos Férricos/química , Lipossomos/química , Proteínas de Membrana/química , Nanomedicina , Tamanho da Partícula , Espectrometria de Massas em Tandem , Titânio/química
15.
Soft Matter ; 15(21): 4301-4310, 2019 May 29.
Artigo em Inglês | MEDLINE | ID: mdl-31070658

RESUMO

Experiments have revealed that membrane proteins often self-assemble into locally ordered clusters. Such membrane protein lattices can play key roles in the functional organization of cell membranes. Membrane protein organization can be driven, at least in part, by bilayer-mediated elastic interactions between membrane proteins. For membrane proteins with anisotropic hydrophobic thickness, bilayer-mediated protein interactions are inherently directional. Here we establish general relations between anisotropy in membrane protein hydrophobic thickness and supramolecular membrane protein organization. We show that protein symmetry is distinctively reflected in the energy landscape of bilayer-mediated protein interactions, favoring characteristic lattice architectures of membrane protein clusters. We find that, in the presence of thermal fluctuations, anisotropy in protein hydrophobic thickness can induce membrane proteins to form mesh-like structures dividing the membrane into compartments. Our results help to elucidate the physical principles and mechanisms underlying the functional organization of cell membranes.


Assuntos
Interações Hidrofóbicas e Hidrofílicas , Proteínas de Membrana/química , Anisotropia , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Proteínas de Membrana/metabolismo , Modelos Moleculares
16.
Gene ; 707: 86-92, 2019 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-31071385

RESUMO

Retinitis pigmentosa (RP) is the most common form of inherited retinal degenerative diseases. X-linked RP accounts for nearly 15% of all RP cases. In this study, we identified a novel RP2 missense mutation Q158P in a Chinese XLRP family. The RP2 Q158P mutation located in the RP2 TBCC domain and obviously destabilized RP2 protein in ARPE-19 cells. The proteasome inhibitor MG132 could restore the RP2 Q158P protein levels. Meanwhile, lower doses of bortezomib and carfilzomib, another two proteasome inhibitors that have been approved in multiple myeloma clinical therapy, also could rescue the RP2 Q158P protein levels. The ubiquitination of RP2 Q158P protein obviously increased when compared with wild type RP2 protein. Our findings broadened the spectrum of RP2 mutations and may contribute a better understanding of the molecular mechanism of XLRP.


Assuntos
Proteínas do Olho/química , Proteínas do Olho/genética , Doenças Genéticas Ligadas ao Cromossomo X/genética , Peptídeos e Proteínas de Sinalização Intracelular/química , Peptídeos e Proteínas de Sinalização Intracelular/genética , Proteínas de Membrana/química , Proteínas de Membrana/genética , Mutação de Sentido Incorreto , Retinite Pigmentosa/genética , Linhagem Celular , China , Análise Mutacional de DNA , Feminino , Humanos , Masculino , Modelos Moleculares , Linhagem , Domínios Proteicos , Estabilidade Proteica , Análise de Sequência de DNA
17.
Talanta ; 200: 526-536, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31036219

RESUMO

In this work, a novel thermosensitive surface protein imprinted polymer monolithic column (TsIPMC) was synthesized by combining high internal phase emulsion with 1,1-diphenylethene (DPE) controlled polymerization. Innovatively, DPE and acrylic acid (AA) monomers were introduced in high internal oil and water phases respectively. The research showed that DPE could not only initiate the polymerization of monomers, but also improve the pore performance of monolithic columns. The elution efficiency of template or target protein could be significantly improved by the thermoresponse characteristics of TsIPMC. The effects of DPE and AA on adsorption capacity and imprinting factor (IF) were studied. The optimization results presented that the optimal addition amounts were 55 mg and 50 mg. Under such conditions, the IF of as-prepared TsIPMC was 1.61 and the saturated adsorption capacity was 66 mg/mL. The influences of the flow rate and target protein concentration on the adsorption equilibrium time and effluent volume were revealed. TsIPMC showed higher selectivity for different competing proteins. The reuse stability result showed that the adsorption of TsIPMC to BSA decreased by 3.69% after 12 times of reuse, and the IF remained basically unchanged. TsIPMC would demonstrate the potential applications in the field of protein purification and separation.


Assuntos
Proteínas de Membrana/química , Impressão Molecular , Polímeros/química , Soroalbumina Bovina/química , Temperatura Ambiente , Adsorção , Animais , Bovinos , Tamanho da Partícula , Polímeros/síntese química , Propriedades de Superfície
18.
Science ; 364(6438): 389-394, 2019 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-31023924

RESUMO

Membrane-integral adenylyl cyclases (ACs) are key enzymes in mammalian heterotrimeric GTP-binding protein (G protein)-dependent signal transduction, which is important in many cellular processes. Signals received by the G protein-coupled receptors are conveyed to ACs through G proteins to modulate the levels of cellular cyclic adenosine monophosphate (cAMP). Here, we describe the cryo-electron microscopy structure of the bovine membrane AC9 bound to an activated G protein αs subunit at 3.4-angstrom resolution. The structure reveals the organization of the membrane domain and helical domain that spans between the membrane and catalytic domains of AC9. The carboxyl-terminal extension of the catalytic domain occludes both the catalytic and the allosteric sites of AC9, inducing a conformation distinct from the substrate- and activator-bound state, suggesting a regulatory role in cAMP production.


Assuntos
Adenilil Ciclases/química , Membrana Celular/enzimologia , Subunidades alfa Gs de Proteínas de Ligação ao GTP/química , Proteínas de Membrana/química , Adenilil Ciclases/ultraestrutura , Animais , Domínio Catalítico , Bovinos , Microscopia Crioeletrônica , AMP Cíclico/química , Subunidades alfa Gs de Proteínas de Ligação ao GTP/ultraestrutura , Proteínas de Membrana/ultraestrutura , Transdução de Sinais
19.
Int J Mol Sci ; 20(8)2019 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-31018575

RESUMO

The merlin-ERM (ezrin, radixin, moesin) family of proteins plays a central role in linking the cellular membranes to the cortical actin cytoskeleton. Merlin regulates contact inhibition and is an integral part of cell-cell junctions, while ERM proteins, ezrin, radixin and moesin, assist in the formation and maintenance of specialized plasma membrane structures and membrane vesicle structures. These two protein families share a common evolutionary history, having arisen and separated via gene duplication near the origin of metazoa. During approximately 0.5 billion years of evolution, the merlin and ERM family proteins have maintained both sequence and structural conservation to an extraordinary level. Comparing crystal structures of merlin-ERM proteins and their complexes, a picture emerges of the merlin-ERM proteins acting as switchable interaction hubs, assembling protein complexes on cellular membranes and linking them to the actin cytoskeleton. Given the high level of structural conservation between the merlin and ERM family proteins we speculate that they may function together.


Assuntos
Membrana Celular/metabolismo , Proteínas do Citoesqueleto/metabolismo , Proteínas de Membrana/metabolismo , Proteínas dos Microfilamentos/metabolismo , Neurofibromina 2/metabolismo , Citoesqueleto de Actina/metabolismo , Sequência de Aminoácidos , Animais , Membrana Celular/química , Inibição de Contato , Proteínas do Citoesqueleto/química , Humanos , Proteínas de Membrana/química , Proteínas dos Microfilamentos/química , Modelos Moleculares , Neurofibromina 2/química , Conformação Proteica , Domínios Proteicos , Mapas de Interação de Proteínas , Alinhamento de Sequência
20.
Comput Biol Chem ; 80: 168-176, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30965174

RESUMO

The alarm is rang for friendly fire; Saccharomyces cerevisiae (S. cerevisiae) newfound as a fungal pathogen with an individual feature. S. cerevisiae has food safety and is not capable of producing infection but, when the host defenses are weakened, there is room for opportunistic S. cerevisiae strains to cause a health issues. Fungal diseases are challenging to treat because, unlike bacteria, the fungal are eukaryotes. Antibiotics only target prokaryotic cells, whereas compounds that kill fungi also harm the mammalian host. Small differences between mammalian and fungal cells regarding genes and proteins sequence and function make finding a drug target more challenging. Recently, Chitin synthase has been considered as a promising target for antifungal drug development as it is absent in mammals. In S. cerevisiae, CHS3, a class IV chitin synthase, produces 90% of the chitin and essential for cell growth. CHS3 from the trans-Golgi network to the plasma membrane requires assembly of the exomer complex (including proteins cargo such as CHS5, CHS6, Bach1, and Arf1). In this work, we performed SELEX (Systematic Evolution of Ligands by EXponential enrichment) as high throughput virtual screening of the RCSB data bank to find an aptamer as potential inhibit of the class IV chitin synthase of S. cerevisiae. Among all the candidates, G-rich VEGF (GVEGF) aptamer (PDB code: 2M53) containing locked sugar parts was observed as potential inhibitor of the assembly of CHS5-CHS6 exomer complex a subsequently block the chitin biosynthesis pathway as an effective anti-fungal. It was suggested from the simulation that an assembly of exomer core should begin CHS5-CHS6, not from CHS5-Bach1. It is notable that secondary structures of CHS6 and Bach1 was observed very similar, but they have only 25% identity at the amino acid sequence that exhibited different features in exomer assembly.


Assuntos
Proteínas Adaptadoras de Transporte Vesicular/metabolismo , Aptâmeros de Nucleotídeos/metabolismo , Quitina Sintase/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Proteínas de Membrana/metabolismo , Multimerização Proteica/efeitos dos fármacos , Proteínas de Saccharomyces cerevisiae/metabolismo , Fator A de Crescimento do Endotélio Vascular/química , Proteínas Adaptadoras de Transporte Vesicular/química , Sequência de Aminoácidos , Antifúngicos/metabolismo , Aptâmeros de Nucleotídeos/genética , Sítios de Ligação , Quitina Sintase/química , Quadruplex G , Peptídeos e Proteínas de Sinalização Intracelular/química , Proteínas de Membrana/química , Simulação de Acoplamento Molecular , Ligação Proteica , Técnica de Seleção de Aptâmeros , Saccharomyces cerevisiae/enzimologia , Proteínas de Saccharomyces cerevisiae/química , Alinhamento de Sequência
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