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1.
BMC Cancer ; 20(1): 1150, 2020 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-33238978

RESUMO

BACKGROUND: Whether tumour-infiltrating lymphocytes (TILs) play different roles in different molecular subtypes of breast cancer remains unknown. Additionally, their prognostic and predictive value in different molecular subtypes of breast cancer is still controversial. The aim of our meta-analysis was to assess the prognostic and predictive value of TILs in different molecular subtypes of breast cancer by summarizing all relevant studies performing multivariate analysis. METHODS: PubMed, Embase, EBSCO, ScienceDirect, the Cochrane Database and Web of Science were comprehensively searched (until March 2020). Hazard ratios (HRs), odds ratios (ORs) and their 95% confidence intervals (CIs) were used as effect measures to perform our meta-analysis. A random effect model was used. Stata software, version 15 (2017) (StataCorp, College Station, TX, USA) was used to perform the statistical analysis. RESULTS: Thirty-three studies including 18,170 eligible breast cancer patients were analysed. The meta-analysis showed that high TIL expression was significantly associated with increased pathological complete response (pCR) rates after neoadjuvant chemotherapy in patients with the HER2-enriched molecular subtype (OR = 1.137, 95% CI [1.061 ~ 1.218], p < 0.001) and triple-negative breast cancer (TNBC) subtype (OR = 1.120, 95% CI [1.061 ~ 1.182], p < 0.001). However, high TIL expression was not significantly associated with high pCR rates after neoadjuvant chemotherapy in patients with the luminal molecular subtype of breast cancer (OR = 1.154, 95% CI [0.789 ~ 1.690], p = 0.460). We carried out a meta-analysis on the HRs of overall survival (OS) and disease-free survival (DFS) to assess the prognostic value of TILs in breast cancer with different molecular subtypes more deeply. Our meta-analysis confirmed that high TILs were associated with significantly improved DFS in patients with the HER2-enriched molecular subtype [HR = 0.940, 95% CI (0.903 ~ 0.979), p = 0.003] and TNBC molecular subtype [HR = 0.907, 95% CI (0.862 ~ 0.954), p < 0.001]. However, high TILs were not associated with significantly better DFS in patients with the luminal molecular subtype of breast cancer [HR = 0.998, 95% CI (0.977 ~ 1.019), p = 0.840]. Furthermore, the results confirmed that high TILs were significantly related to better OS in patients with the HER2-enriched molecular subtype [HR = 0.910, 95% CI (0.866 ~ 0.957), p < 0.001] and TNBC molecular subtype [HR = 0.869, 95% CI (0.836 ~ 0.904), p < 0.001]. Conversely, the summarized results indicated that high TILs were significantly associated with poor OS in patients with the luminal molecular subtype of breast cancer [HR = 1.077, 95% CI (1.016 ~ 1.141), p = 0.012]. CONCLUSIONS: Our meta-analysis confirms that high TILs are associated with favourable survival and predicts pCR in breast cancer patients with the TNBC and HER2-enriched molecular subtypes.


Assuntos
Protocolos de Quimioterapia Combinada Antineoplásica/uso terapêutico , Biomarcadores Tumorais/metabolismo , Neoplasias da Mama/patologia , Carcinoma Ductal de Mama/patologia , Carcinoma Lobular/patologia , Linfócitos do Interstício Tumoral/imunologia , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/imunologia , Neoplasias da Mama/metabolismo , Carcinoma Ductal de Mama/tratamento farmacológico , Carcinoma Ductal de Mama/imunologia , Carcinoma Ductal de Mama/metabolismo , Carcinoma Lobular/tratamento farmacológico , Carcinoma Lobular/imunologia , Carcinoma Lobular/metabolismo , Feminino , Humanos , Terapia Neoadjuvante , Prognóstico , Receptor ErbB-2/metabolismo , Receptores de Estrogênio/metabolismo , Receptores de Progesterona/metabolismo
2.
Ann Thorac Surg ; 110(5): e441-e443, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32492438

RESUMO

Because the segmental bronchi and vessels are commonly variable and complicated, it is difficult to correctly identify them. Misidentification of the segmental anatomy could result in the failure of segmentectomy and conversion to other surgical procedures such as bisegmentectomy or lobectomy. We describe a novel method to identify the target segmental vessels and bronchi by exposing the adjacent segmental anatomy during uniportal video-assisted thoracoscopic segmentectomy, which could help to reduce the chance of misidentification.


Assuntos
Neoplasias Pulmonares/cirurgia , Pneumonectomia/métodos , Cirurgia Torácica Vídeoassistida/métodos , Angiografia , Broncografia , Humanos , Neoplasias Pulmonares/diagnóstico por imagem , Tomografia Computadorizada por Raios X
3.
Fish Physiol Biochem ; 44(4): 1159-1174, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29730709

RESUMO

This study aimed to investigate the effects of lysine supplement on the growth performance of blunt snout bream Megalobrama amblycephala fed diets with fish meal (FM) replaced by rice protein concentrate (RPC) with the potential mechanisms characterized. Fish were fed three diets, including the FM diet (containing FM), the RPC diet (FM replaced by RPC), and the MRPC diet (the RPC diet supplemented with lysine) for 8 weeks. Weight gain, protein efficiency ratio, and nitrogen and energy utilization of fish fed the FM diet were all significantly higher than those of the RPC treatment, but they showed no statistical difference with those of the MRPC group. Fish fed the RPC diet showed shorter villi length of the distal intestine than that of the other treatments. No significance was found in whole-body composition and intestinal and hepatic cell proliferation among all the treatments. However, fish fed the RPC diet obtained relatively low transcriptions of growth hormone (GH), GH receptor, insulin-like growth factor-I (IGF-I), target of rapamycin (TOR), ribosomal protein S6 kinase 1, myoblast determination protein, myogenic factor 5, and myostatin a (MSTNa) but high levels of eukaryotic translation initiation factor 4E-binding protein 2 (4E-BP2) than those of the other groups. Furthermore, little difference was found in the transcriptions of 4E-BP2, myogenin, muscle-specific regulatory 4, and MSTNb in muscle. Overall, these results showed that dietary supplement of lysine benefits the growth performance of blunt snout bream fed FM-free diets through the mediation of the GH-IGF-I axis, TOR signaling pathway, myogenic regulatory factors, and MSTN.


Assuntos
Ração Animal/análise , Cyprinidae/crescimento & desenvolvimento , Dieta/veterinária , Lisina/administração & dosagem , Oryza/química , Proteínas de Vegetais Comestíveis/administração & dosagem , Animais , Cyprinidae/metabolismo , Suplementos Nutricionais , Proteínas de Peixes/metabolismo , Desenvolvimento Muscular/efeitos dos fármacos , Biossíntese de Proteínas
4.
Fish Shellfish Immunol ; 67: 312-321, 2017 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-28606860

RESUMO

A 10-week feeding trial was carried out to investigate the effects of dietary fish meal replacement by yeast hydrolysate (YH) on growth performance, complement system and stress resistance of juvenile Jian carp (Cyprinus carpio var. Jian) (initial average weight 19.44 ± 0.06 g). In the study, there were five groups: one control group was fed with a basal diet (YH0), and four treatment groups were fed with dietary fish meal replaced by 1% YH (YH1), 3% (YH3), 5% (YH5) and 7% (YH7), respectively. Each group had four replicates. At the end of feeding trial, twelve fish from each group (three fish per replicate) were randomly selected for assessing the growth and immunity. Meanwhile, 20 fish per replicate were injected by Aeromonas hydrophila. The results showed that (1) Replacement levels of YH significantly affected the growth of the fish with the highest values of weight gain (WG) occurred in fish fed YH3 diet. However, no significant difference in feed conversion ratios (FCR) was observed among all groups. (2) Pre-stressed plasma lysozyme activity, total protein and albumin contents and complement component 3 (C3) and complement component 4 (C4) levels of fish fed YH3 diet were significantly higher than those of fish fed YH0 diet. However, post-stressed immune parameters of fish in all groups were significantly lower. (3) There was a trend that the expression levels of the complement-related genes (c1r/s-A, c4-1, c3-H1, c5-1, fb/c2-A, mbl-2 and masp) initially increased and then decreased except mbl-2 and masp, with the maximum values observed in fish fed YH3 diet. Before stress, the expression levels of the inflammation-related genes (alp, il-1ß and tnf-α) in the hepatopancreas and spleen of fish fed YH1 diet and YH7 diet were significant higher than that of fish fed YH0 diet. After stress, no significant difference in the expression levels of those genes was observed among all groups. These results indicated that FM replacement by YH could improve growth performance, enhance innate immunity, and activate complement via the alternative complement pathway (ACP) and the classical complement pathway (CCP).


Assuntos
Carpas/imunologia , Suplementos Nutricionais , Imunidade Inata , Saccharomyces cerevisiae , Estresse Fisiológico/imunologia , Ração Animal/análise , Animais , Carpas/genética , Complemento C3/metabolismo , Complemento C4/metabolismo , Dieta/veterinária , Proteínas de Peixes/metabolismo , Distribuição Aleatória
5.
ACS Nano ; 11(6): 6211-6217, 2017 06 27.
Artigo em Inglês | MEDLINE | ID: mdl-28489941

RESUMO

We developed a high-efficiency rotating triboelectric nanogenerator (R-TENG) enhanced polyimide (PI) nanofiber air filter for particulate matter (PM) removal in ambient atmosphere. The PI electrospinning nanofiber film exhibited high removal efficiency for the PM particles that have diameters larger than 0.5 µm. When the R-TENG is connected, the removal efficiency of the filter is enhanced, especially when the particle diameters of the PM are smaller than 100 nm. The highest removal efficiency is 90.6% for particles with a diameter of 33.4 nm and the highest efficiency enhancement reaches 207.8% at the diameter of 76.4 nm where the removal efficiency enhanced from 27.1% to 83.6%. This technology with zero ozone release and low pressure drop offers an approach for air cleaning and haze treatment.

6.
Spine J ; 17(7): 1017-1025, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28343048

RESUMO

BACKGROUND CONTEXT: Intervertebral disc degeneration (IDD) is the main cause of low back pain, and nucleus pulposus (NP) cell apoptosis is an important risk factor of IDD. However, the molecular mechanism of this disease remains unknown. PURPOSE: To assess the potential protective effect of CDDO-ethyl amide (EA) against high-glucose-induced oxidative stress injury in NP cells and to investigate the mechanism of antioxidative effects and apoptotic inhibition. STUDY DESIGN/SETTING: To find new molecule to inhibit intervertebral disc degeneration. METHODS: Viability, reactive oxygen species (ROS) levels, and apoptosis were examined in NP cells. The protein expression levels of HO-1 and Nrf2 were measured through Western blot RESULTS: CDDO-EA elicited cytoprotective effects against NP cell apoptosis and ROS accumulation induced by high glucose. CDDO-EA treatment increased the HO-1 and Nrf2 expression abrogated by HO-1, Nrf2, and mitogen-activated protein kinase inhibitors. CONCLUSIONS: The phosphorylation and nuclear translocation of Nrf2 are crucial for HO-1 overexpression induced by CDDO-EA, which is essential for the cytoprotection against high-glucose-induced oxidative stress in NP cells.


Assuntos
Antioxidantes/farmacologia , Núcleo Pulposo/efeitos dos fármacos , Ácido Oleanólico/análogos & derivados , Animais , Apoptose , Células Cultivadas , Citoproteção , Glucose/toxicidade , Heme Oxigenase-1/metabolismo , Fator 2 Relacionado a NF-E2/metabolismo , Núcleo Pulposo/metabolismo , Ácido Oleanólico/farmacologia , Estresse Oxidativo , Coelhos , Espécies Reativas de Oxigênio/metabolismo
7.
ACS Appl Mater Interfaces ; 9(13): 11882-11888, 2017 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-28299934

RESUMO

As a green and eco-friendly technology, triboelectric nanogenerator (TENG) can harvest energy from human motion to generate electricity, so TENGs have been widely applied in wearable electronic devices to replace traditional batteries. However, the surface of these TENGs is easily contaminated and breeds bacteria, which is a threat to human health. Here, we report an antibacterial composite film-based triboelectric nanogenerator (ACF-TENG) that uses Ag-exchanged zeolite (Ag-zeolite) and polypropylene (PP) composite film as the triboelectric layer. Adding a small amount of Ag-zeolite with excellent antibacterial properties can increase the dielectric permittivity and improve the surface charge density of composite films, which enhances the output performance of the ACF-TENG. The open-circuit voltage (VOC), short-circuit current (ISC), and transferred charge (QTr) of the ACF-TENG are about 193.3, 225.4, and 233.3% of those of a pure PP film-based TENG, respectively. Because of the silver in the Ag-zeolite, the ACF-TENG can effectively kill Escherichia coli and fungi. When used in insoles, the ACF-TENG can resist the athlete's foot fungus effectively and work as a power source to light up light-emitting diodes and charge capacitors. The ACF-TENG has wide application prospects in self-powered medical and healthcare electronics.

8.
Proteins ; 85(4): 741-752, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28120375

RESUMO

Protein-RNA docking is still an open question. One of the main challenges is to develop an effective scoring function that can discriminate near-native structures from the incorrect ones. To solve the problem, we have constructed a knowledge-based residue-nucleotide pairwise potential with secondary structure information considered for nonribosomal protein-RNA docking. Here we developed a weighted combined scoring function RpveScore that consists of the pairwise potential and six physics-based energy terms. The weights were optimized using the multiple linear regression method by fitting the scoring function to L_rmsd for the bound docking decoys from Benchmark II. The scoring functions were tested on 35 unbound docking cases. The results show that the scoring function RpveScore including all terms performs best. Also RpveScore was compared with the statistical mechanics-based method derived potential ITScore-PR, and the united atom-based statistical potentials QUASI-RNP and DARS-RNP. The success rate of RpveScore is 71.6% for the top 1000 structures and the number of cases where a near-native structure is ranked in top 30 is 25 out of 35 cases. For 32 systems (91.4%), RpveScore can find the binding mode in top 5 that has no lower than 50% native interface residues on protein and nucleotides on RNA. Additionally, it was found that the long-range electrostatic attractive energy plays an important role in distinguishing near-native structures from the incorrect ones. This work can be helpful for the development of protein-RNA docking methods and for the understanding of protein-RNA interactions. RpveScore program is available to the public at http://life.bjut.edu.cn/kxyj/kycg/2017116/14845362285362368_1.html Proteins 2017; 85:741-752. © 2016 Wiley Periodicals, Inc.


Assuntos
Aminoacil-tRNA Sintetases/química , Simulação de Acoplamento Molecular , NF-kappa B/química , Proteínas de Ligação a RNA/química , RNA/química , Aminoacil-tRNA Sintetases/metabolismo , Sítios de Ligação , Humanos , NF-kappa B/metabolismo , Ligação Proteica , Conformação Proteica , RNA/metabolismo , Proteínas de Ligação a RNA/metabolismo , Projetos de Pesquisa
9.
Proteins ; 83(9): 1643-53, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26148303

RESUMO

The transporter MsbA is a kind of multidrug resistance ATP-binding cassette transporter that can transport lipid A, lipopolysaccharides, and some amphipathic drugs from the cytoplasmic to the periplasmic side of the inner membrane. In this work, we explored the allosteric pathway of MsbA from the inward- to outward-facing states during the substrate transport process with the adaptive anisotropic network model. The results suggest that the allosteric transitions proceed in a coupled way. The large-scale closing motions of the nucleotide-binding domains occur first, accompanied with a twisting motion at the same time, which becomes more obvious in middle and later stages, especially for the later. This twisting motion plays an important role for the rearrangement of transmembrane helices and the opening of transmembrane domains on the periplasmic side that mainly take place in middle and later stages respectively. The topological structure plays an important role in the motion correlations above. The conformational changes of nucleotide-binding domains are propagated to the transmembrane domains via the intracellular helices IH1 and IH2. Additionally, the movement of the transmembrane domains proceeds in a nonrigid body, and the two monomers move in a symmetrical way, which is consistent with the symmetrical structure of MsbA. These results are helpful for understanding the transport mechanism of the ATP-binding cassette exporters.


Assuntos
Transportadores de Cassetes de Ligação de ATP/química , Algoritmos , Proteínas de Bactérias/química , Modelos Moleculares , Conformação Proteica , Transportadores de Cassetes de Ligação de ATP/metabolismo , Anisotropia , Proteínas de Bactérias/metabolismo , Sítios de Ligação , Simulação por Computador , Escherichia coli/metabolismo , Cinética , Movimento (Física) , Periplasma/metabolismo , Ligação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
10.
Biopolymers ; 101(7): 758-68, 2014 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-24865820

RESUMO

The maltose transporter from Escherichia coli is one of the ATP-binding cassette (ABC) transporters that utilize the energy from ATP hydrolysis to translocate substrates across cellular membranes. Until 2011, three crystal structures have been determined for maltose transporter at different states in the process of transportation. Here, based on these crystal structures, the allosteric pathway from the resting state (inward-facing) to the catalytic intermediate state (outward-facing) is studied by applying an adaptive anisotropic network model. The results suggest that the allosteric transitions proceed in a coupled way. The closing of the nucleotide-binding domains occurs first, and subsequently this conformational change is propagated to the transmembrane domains (TMD) via the EAA and EAS loops, and then to the maltose-binding protein, which facilitates the translocation of the maltose. It is also found that there exist nonrigid-body and asymmetric movements in the TMD. The cytoplasmic gate may only play the role of allosteric propagation during the transition from the pretranslocation to outward-facing states. In addition, the results show that the movment of the helical subdomain towards the RecA-like subdomain mainly occurs in the earlier stages of the transition. These results can provide some insights into the understanding of the mechanism of ABC transporters.


Assuntos
Transportadores de Cassetes de Ligação de ATP/química , Proteínas de Escherichia coli/química , Maltose/química , Modelos Biológicos , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína , Transportadores de Cassetes de Ligação de ATP/metabolismo , Algoritmos , Anisotropia , Sítios de Ligação , Transporte Biológico , Simulação por Computador , Cristalografia por Raios X , Citoplasma/metabolismo , Proteínas de Escherichia coli/metabolismo , Cinética , Maltose/metabolismo , Modelos Moleculares , Periplasma/metabolismo
11.
BMC Struct Biol ; 13: 16, 2013 Sep 22.
Artigo em Inglês | MEDLINE | ID: mdl-24053684

RESUMO

BACKGROUND: Persistent organic pollutants (POPs) are persistent in the environment after release from industrial compounds, combustion productions or pesticides. The exposure of POPs has been related to various reproductive disturbances, such as reduced semen quality, testicular cancer, and imbalanced sex ratio. Among POPs, dichlorodiphenyldichloroethylene (4,4'-DDE) and polychlorinated biphenyls (PCBs) are the most widespread and well-studied compounds. Recent studies have revealed that 4,4'-DDE is an antagonist of androgen receptor (AR). However, the mechanism of the inhibition remains elusive. CB-153 is the most common congener of PCBs, while the action of CB-153 on AR is still under debate. RESULTS: Molecular docking and molecular dynamics (MD) approaches have been employed to study binding modes and inhibition mechanism of 4,4'-DDE and CB-153 against AR ligand binding domain (LBD). Several potential binding sites have been detected and analyzed. One possible binding site is the same binding site of AR natural ligand androgen 5α-dihydrotestosterone (DHT). Another one is on the ligand-dependent transcriptional activation function (AF2) region, which is crucial for the co-activators recruitment. Besides, a novel possible binding site was observed for POPs with low binding free energy with the receptor. Detailed interactions between ligands and the receptor have been represented. The disrupting mechanism of POPs against AR has also been discussed. CONCLUSIONS: POPs disrupt the function of AR through binding to three possible biding sites on AR/LBD. One of them shares the same binding site of natural ligand of AR. Another one is on AF2 region. The third one is in a cleft near N-terminal of the receptor. Significantly, values of binding free energy of POPs with AR/LBD are comparable to that of natural ligand androgen DHT.


Assuntos
Diclorodifenil Dicloroetileno/metabolismo , Poluentes Ambientais/metabolismo , Modelos Moleculares , Bifenilos Policlorados/metabolismo , Receptores Androgênicos/química , Receptores Androgênicos/metabolismo , Sítios de Ligação , Domínio Catalítico , Di-Hidrotestosterona/metabolismo , Humanos , Ligantes , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Ligação Proteica , Conformação Proteica , Estabilidade Proteica , Estrutura Terciária de Proteína
12.
J Phys Chem B ; 117(29): 8689-96, 2013 Jul 25.
Artigo em Inglês | MEDLINE | ID: mdl-23822189

RESUMO

AMPA receptor mediates the fast excitatory synaptic transmission in the central nervous system, and it is activated by the binding of glutamate that results in the opening of the transmembrane ion channel. In the present work, the thermodynamic method developed by our group was improved and then applied to identify the functionally key residues that regulate the glutamate-binding affinity of AMPA receptor. In our method, the key residues are identified as those whose perturbation largely changes the ligand binding free energy of the protein. It is found that besides the ligand binding sites, other residues distant from the binding cleft can also influence the glutamate binding affinity through a long-range allosteric regulation. These allosteric sites include the hinge region of the ligand binding cleft, the dimer interface of the ligand binding domain, the linkers between the ligand binding domain and the transmembrane domain, and the interface between the N-terminal domain and the ligand binding domain. Our calculation results are consistent with the available experimental data. The results are helpful for our understanding of the mechanism of long-range allosteric communication in the AMPA receptor and the mechanism of channel opening triggered by glutamate binding.


Assuntos
Receptores de AMPA/química , Termodinâmica , Regulação Alostérica , Sítios de Ligação , Cristalografia por Raios X , Ligantes , Modelos Moleculares
13.
Curr Pharm Des ; 19(10): 1810-7, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23092283

RESUMO

HIV-1 membrane fusion as a part of the process of viral entry in the target cells is facilitated by gp41 and gp120, which are encoded by Env gene of HIV-1. Based on the structure and the mechanism researches, new treatment options targeting HIV-1 entry process have been proposed. Enfuvirtide, which mimics amino acid sequences of viral envelope glycoprotein gp41, is the first HIV-1 fusion inhibitor approved by FDA. Although it fulfills vital functions by binding to gp41 and abolishing the membrane fusion reaction when used in combination, it could induce drug resistant virus variants. Currently, a number of design and modification schemes have been presented, a large number of prospective fusion peptides have emerged. For these fusion inhibitors, multiple mutations in gp41 have been associated with the loss of susceptibility to agents. This review reported the current developments and innovative designs of HIV-1 membrane fusion inhibitors.


Assuntos
Inibidores da Fusão de HIV/uso terapêutico , Infecções por HIV/tratamento farmacológico , HIV-1/efeitos dos fármacos , Fusão de Membrana/efeitos dos fármacos , Sequência de Aminoácidos , Proteína gp41 do Envelope de HIV/química , Inibidores da Fusão de HIV/química , Inibidores da Fusão de HIV/farmacologia , HIV-1/fisiologia , Humanos , Dados de Sequência Molecular
15.
J Biomol Struct Dyn ; 31(3): 276-87, 2013 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-22943434

RESUMO

The interaction of HIV-1 trans-activator protein Tat with its cognate trans-activation response element (TAR) RNA is critical for viral transcription and replication. Therefore, it has long been considered as an attractive target for the development of antiviral compounds. Recently, the conformationally constrained cyclic peptide mimetics of Tat have been tested to be a promising family of lead peptides. Here, we focused on two representative cyclic peptides termed as L-22 and KP-Z-41, both of which exhibit excellent inhibitory potency against Tat and TAR interaction. By means of molecular dynamics simulations, we obtained a detailed picture of the interactions between them and HIV-1 TAR RNA. In results, it is found that the binding modes of the two cyclic peptides to TAR RNA are almost identical at or near the bulge regions, whereas the binding interfaces at the apical loop exhibit large conformational heterogeneity. In addition, it is revealed that electrostatic interaction energy contributes much more to KP-Z-41 complex formation than to L-22 complex, which is the main source of energy that results in a higher binding affinity of KP-Z-41 over-22 for TAR RNA. Furthermore, we identified a conserved motif RRK (Arg-Arg-Lys) that is shown to be essential for specific binding of this class of cyclic peptides to TAR RNA. This work can provide a useful insight into the design and modification of cyclic peptide inhibitors targeting the association of HIV-1 Tat and TAR RNA.


Assuntos
Repetição Terminal Longa de HIV/genética , HIV-1/genética , HIV-1/metabolismo , Simulação de Dinâmica Molecular , Peptídeos Cíclicos/metabolismo , Produtos do Gene tat do Vírus da Imunodeficiência Humana/metabolismo , Sequência de Aminoácidos , Humanos , Ligação de Hidrogênio , Dados de Sequência Molecular , Peptídeos Cíclicos/química , Ligação Proteica , Alinhamento de Sequência , Termodinâmica , Fatores de Tempo , Produtos do Gene tat do Vírus da Imunodeficiência Humana/química
16.
Proteins ; 80(1): 14-24, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21953889

RESUMO

Understanding the key factors that influence the preferences of residue-nucleotide interactions in specific protein-RNA interactions has remained a research focus. We propose an effective approach to derive residue-nucleotide propensity potentials through considering both the types of residues and nucleotides, and secondary structure information of proteins and RNAs from the currently largest nonredundant and nonribosomal protein-RNA interaction database. To test the validity of the potentials, we used them to select near-native structures from protein-RNA docking poses. The results show that considering secondary structure information, especially for RNAs, greatly improves the predictive power of pair potentials. The success rate is raised from 50.7 to 65.5% for the top 2000 structures, and the number of cases in which a near-native structure is ranked in top 50 is increased from 7 to 13 out of 17 cases. Furthermore, the exclusion of ribosomes from the database contributes 8.3% to the success rate. In addition, some very interesting findings follow: (i) the protein secondary structure element π-helix is strongly associated with RNA-binding sites; (ii) the nucleotide uracil occurs frequently in the most preferred pairs in which the unpaired and non-Watson-Crick paired uracils are predominant, which is probably significant in evolution. The new residue-nucleotide potentials can be helpful for the progress of protein-RNA docking methods, and for understanding the mechanisms of protein-RNA interactions.


Assuntos
Aminoácidos/química , Proteínas de Ligação a RNA/química , RNA/química , Ribonucleotídeos/química , Sítios de Ligação , Simulação por Computador , Bases de Dados de Proteínas , Ligação de Hidrogênio , Modelos Moleculares , Conformação de Ácido Nucleico , Ligação Proteica , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
17.
J Chem Phys ; 135(17): 174101, 2011 Nov 07.
Artigo em Inglês | MEDLINE | ID: mdl-22070286

RESUMO

Proteins usually undergo conformational transitions between structurally disparate states to fulfill their functions. The large-scale allosteric conformational transitions are believed to involve some key residues that mediate the conformational movements between different regions of the protein. In the present work, a thermodynamic method based on the elastic network model is proposed to predict the key residues involved in protein conformational transitions. In our method, the key functional sites are identified as the residues whose perturbations largely influence the free energy difference between the protein states before and after transition. Two proteins, nucleotide binding domain of the heat shock protein 70 and human/rat DNA polymerase ß, are used as case studies to identify the critical residues responsible for their open-closed conformational transitions. The results show that the functionally important residues mainly locate at the following regions for these two proteins: (1) the bridging point at the interface between the subdomains that control the opening and closure of the binding cleft; (2) the hinge region between different subdomains, which mediates the cooperative motions between the corresponding subdomains; and (3) the substrate binding sites. The similarity in the positions of the key residues for these two proteins may indicate a common mechanism in their conformational transitions.


Assuntos
DNA Polimerase beta/química , Proteínas de Choque Térmico HSP70/química , Conformação Proteica , Regulação Alostérica , Animais , DNA Polimerase beta/metabolismo , Elasticidade , Proteínas de Choque Térmico HSP70/metabolismo , Humanos , Modelos Estatísticos , Distribuição Normal , Ligação Proteica , Ratos , Termodinâmica
18.
Acta Virol ; 55(3): 219-26, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21978155

RESUMO

The H9N2 subtype influenza virus (IV) is a remarkable member of the influenza A viruses because it can infect not only chickens, ducks and pigs, but also humans. Pigs are susceptible to both human and avian influenza viruses and have been proposed to be intermediate hosts for the generation of pandemic influenza viruses through reassortment or adaptation to the mammalian host. To further understand the genetic characteristics and evolution, we investigated the source and molecular characteristics of the H9N2 subtype swine influenza virus (SIV), and observed its pathogenicity in BALB/c mice. The BALB/c mice were inoculated intranasally with 100 median mouse infectious dose of A/swine/HeBei/012/2008/(H9N2) viruses to observe the pathogenicity. The HA, NP, NA and M gene were cloned, sequenced and phylogenetically analyzed with related sequences available in GenBank. The infected mice presented with inactivity, weight loss and laboured respiration, while the pathological changes were characterized by diffuse alveolar damage in the lung. The nucleotide and deduced amino acid sequence of HA, NP, NA and M gene was similar with that of A/chicken/Hebei/4/2008(H9N2). The HA protein contained 6 glycosylation sites and the motif of HA cleavage site was PARSSR GLF, which is characteristic of low pathogenic IV. In the HA, NP, M and NA gene phylogenetic trees, the isolate clustered with A/chicken/Hebei/4/2008(H9N2). The isolate possibly came from A/chicken/Hebei/4/2008(H9N2) and was partially varied during its cross-species spread.


Assuntos
Vírus da Influenza A Subtipo H9N2/isolamento & purificação , Vírus da Influenza A Subtipo H9N2/patogenicidade , Infecções por Orthomyxoviridae/veterinária , Doenças dos Suínos/virologia , Sequência de Aminoácidos , Animais , Embrião de Galinha , Clonagem Molecular , Evolução Molecular , Feminino , Genes Virais , Vírus da Influenza A Subtipo H9N2/fisiologia , Camundongos , Camundongos Endogâmicos BALB C , Dados de Sequência Molecular , Infecções por Orthomyxoviridae/epidemiologia , Infecções por Orthomyxoviridae/genética , Pandemias , Filogenia , Análise de Sequência de DNA , Suínos/virologia , Doenças dos Suínos/epidemiologia , Replicação Viral
19.
J Biomol Struct Dyn ; 29(2): 311-23, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21875151

RESUMO

Integrase is an essential enzyme in the life cycle of Human immunoficiency virus type 1 (HIV-1) and also an important target for designing integrase inhibitors. In this paper, the binding modes between the wild type integrase core domain (ICD) and the W131A mutant ICD with the benzoic acid derivative--D77 were investigated using the molecular docking combined with molecular dynamics (MD) simulations. The result of MD simulations showed that the W131A substitution affected the flexibility of the region 150-167 in both the monomer A and B of the mutant type ICD. In principle, D77 interacted with the residues around the Lens Epithelium-Derived Growth Factor (LEDGF/p75) binding site which is nearby the HIV-1 integrase dimer interface. However, the specific binding modes for D77-wild type integrase and D77-mutant integrase systems are various. According to the binding mode of D77 with the wild type ICD, D77 can effectively intervene with the binding of LEDGF/p75 to integrase due to a steric hindrance effect around the LEDGF/p75 binding site. In addition, we found that D77 might also affect its inhibitory action by reducing the flexibility of the region 150-167 of integrase. Through energy decomposition calculated with the Molecular Mechanics Generalized Born Surface Area approach to estimate the binding affinity, it seems likely that W131 and E170 are indispensable for the ligand binding, as characterized by the largest binding affinity. All the above results are consistent with the experimental data, providing us with some helpful information not only for the understanding of the mechanism of this kind of inhibitor but also for the rational drug design.


Assuntos
Benzoatos/química , Inibidores de Integrase de HIV/química , Integrase de HIV/química , Simulação de Dinâmica Molecular , Tiazolidinedionas/química , Benzoatos/metabolismo , Sítios de Ligação , Desenho de Fármacos , Integrase de HIV/metabolismo , Inibidores de Integrase de HIV/metabolismo , Humanos , Ligação de Hidrogênio , Ligação Proteica , Conformação Proteica , Tiazolidinedionas/metabolismo
20.
J Biomol Struct Dyn ; 29(1): 105-21, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21696228

RESUMO

The influence of the protein topology-encoded dynamical properties on its thermal unfolding motions was studied in the present work. The intrinsic dynamics of protein topology was obtained by the anisotropic network model (ANM). The ANM has been largely used to investigate protein collective functional motions, but it is not well elucidated if this model can also reveal the preferred large-scale motions during protein unfolding. A small protein barnase is used as a typical case study to explore the relationship between protein topology-encoded dynamics and its unfolding motions. Three thermal unfolding simulations at 500 K were performed for barnase and the entire unfolding trajectories were sampled and partitioned into several windows. For each window, the preferred unfolding motions were investigated by essential dynamics analysis, and then associated with the intrinsic dynamical properties of the starting conformation in this window, which is detected by ANM. The results show that only a few slow normal modes imposed by protein structure are sufficient to give a significant overlap with the preferred unfolding motions. Especially, the large amplitude unfolding movements, which imply that the protein jumps out of a local energy basin, can be well described by a single or several ANM slow modes. Besides the global motions, it is also found that the local residual fluctuations encoded in protein structure are highly correlated with those in the protein unfolding process. Furthermore, we also investigated the relationship between protein intrinsic flexibility and its unfolding events. The results show that the intrinsic flexible regions tend to unfold early. Several early unfolding events can be predicted by analysis of protein structural flexibility. These results imply that protein structure-encoded dynamical properties have significant influences on protein unfolding motions.


Assuntos
Desdobramento de Proteína , Proteínas/química , Anisotropia , Simulação por Computador , Modelos Moleculares , Conformação Proteica , Termodinâmica
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