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1.
Lett Appl Microbiol ; 77(1)2024 Jan 02.
Artículo en Inglés | MEDLINE | ID: mdl-38126116

RESUMEN

Fecal microbiota transplantation from patients with depression/inflammatory bowel disease (PDI) causes depression with gut inflammation in mice. Here, we investigated the effects of six Lactobacillus reuteri strains on brain-derived neurotropic factor (BDNF), serotonin, and interleukin (IL)-6 expression in neuronal or macrophage cells and PDI fecal microbiota-cultured microbiota (PcM)-induced depression in mice. Of these strains, L6 most potently increased BDNF and serotonin levels in corticosterone-stimulated SH-SY5Y and PC12 cells, followed by L3. L6 most potently decreased IL-6 expression in lipopolysaccharide (LPS)-stimulated macrophages. When L1 (weakest in vitro), L3, and L6 were orally administered in mice with PcM-induced depression, L6 most potently suppressed depression-like behaviors and hippocampal TNF-α and IL-6 expression and increased hippocampal serotonin, BDNF, 5HT7, GABAARα1, and GABABR1b expression, followed by L3 and L1. L6 also suppressed TNF-α and IL-6 expression in the colon. BDNF or serotonin levels in corticosterone-stimulated neuronal cells were negatively correlated with depression-related biomarkers in PcM-transplanted mice, while IL-6 levels in LPS-stimulated macrophage were positively correlated. These findings suggest that IL-6 expression-suppressing and BDNF/serotonin expression-inducing LBPs in vitro, particularly L6, may alleviate gut microbiota-involved depression with colitis in vivo.


Asunto(s)
Microbioma Gastrointestinal , Limosilactobacillus reuteri , Neuroblastoma , Ratas , Humanos , Ratones , Animales , Interleucina-6/genética , Depresión/terapia , Factor de Necrosis Tumoral alfa/genética , Lipopolisacáridos/toxicidad , Corticosterona/farmacología , Serotonina/farmacología , Factor Neurotrófico Derivado del Encéfalo/genética , Factor Neurotrófico Derivado del Encéfalo/metabolismo , Factor Neurotrófico Derivado del Encéfalo/farmacología , Ansiedad/terapia , Ansiedad/etiología , Ratones Endogámicos C57BL
2.
Proc Natl Acad Sci U S A ; 117(12): 6550-6558, 2020 03 24.
Artículo en Inglés | MEDLINE | ID: mdl-32152123

RESUMEN

The 1918 influenza A virus (IAV) caused the most severe flu pandemic in recorded human history. Nonstructural protein 1 (NS1) is an important virulence factor of the 1918 IAV. NS1 antagonizes host defense mechanisms through interactions with multiple host factors. One pathway by which NS1 increases virulence is through the activation of phosphoinositide 3-kinase (PI3K) by binding to its p85ß subunit. Here we present the mechanism underlying the molecular recognition of the p85ß subunit by 1918 NS1. Using X-ray crystallography, we determine the structure of 1918 NS1 complexed with p85ß of human PI3K. We find that the 1918 NS1 effector domain (1918 NS1ED) undergoes a conformational change to bind p85ß. Using NMR relaxation dispersion and molecular dynamics simulation, we identify that free 1918 NS1ED exists in a dynamic equilibrium between p85ß-binding-competent and -incompetent conformations in the submillisecond timescale. Moreover, we discover that NS1ED proteins of 1918 (H1N1) and Udorn (H3N2) strains exhibit drastically different conformational dynamics and binding kinetics to p85ß. These results provide evidence of strain-dependent conformational dynamics of NS1. Using kinetic modeling based on the experimental data, we demonstrate that 1918 NS1ED can result in the faster hijacking of p85ß compared to Ud NS1ED, although the former has a lower affinity to p85ß than the latter. Our results suggest that the difference in binding kinetics may impact the competition with cellular antiviral responses for the activation of PI3K. We anticipate that our findings will increase the understanding of the strain-dependent behaviors of influenza NS1 proteins.


Asunto(s)
Virus de la Influenza A/fisiología , Gripe Humana/virología , Proteínas no Estructurales Virales/química , Proteínas no Estructurales Virales/metabolismo , Fosfatidilinositol 3-Quinasa Clase Ia/metabolismo , Interacciones Huésped-Patógeno , Humanos , Subtipo H1N1 del Virus de la Influenza A/patogenicidad , Subtipo H1N1 del Virus de la Influenza A/fisiología , Subtipo H3N2 del Virus de la Influenza A/patogenicidad , Subtipo H3N2 del Virus de la Influenza A/fisiología , Virus de la Influenza A/clasificación , Virus de la Influenza A/patogenicidad , Gripe Humana/epidemiología , Unión Proteica , Conformación Proteica , Dominios y Motivos de Interacción de Proteínas , Especificidad de la Especie , Relación Estructura-Actividad , Factores de Virulencia/química , Factores de Virulencia/metabolismo
3.
Korean J Parasitol ; 59(4): 421-426, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34470095

RESUMEN

A 12-year nationwide survey (2008-2019) was performed to investigate the prevalence of Enterobius vermicularis infection among preschool children in Seoul, 4 large cites (Busan, Incheon, Daegu, and Ulsan), and 9 provinces (grouped into 5 localities) in the Republic of Korea (=Korea). The survey was carried out once a year by 16 regional offices of the Korea Association of Health Promotion. The cello-tape perianal swab method (1 smear per child) was applied to detect eggs of E. vermicularis and other helminths. According to the results, the egg positive rate of E. vermicularis infection in 2008-2009 was 1.8-2.0%, but it decreased gradually to 0.6% in 2019 (P<0.05). The prevalence was significantly higher in boys (0.7-5.0%, mean 1.8%) than in girls (0.5-2.8%, mean 1.3%) (P<0.05). The 2 most southern localities, Jejudo (Province) and Jeolla-do (inclusive of Jeollabuk-do and Jeollanam-do) and a mid-western province, Gyeonggi-do, revealed higher prevalences, whereas Seoul and Gangwon-do showed lower prevalences. The results indicate that a low-grade prevalence of E. vermicularis infection (less than 4%) has been maintained for the recent 12 years among preschool children in Korea. Continuous monitoring of enterobiasis in the child age group is necessary in Korea.


Asunto(s)
Enterobiasis , Animales , Preescolar , Ciudades , Enterobiasis/epidemiología , Enterobius , Femenino , Humanos , Masculino , Prevalencia , República de Corea/epidemiología
4.
Biophys J ; 118(10): 2502-2512, 2020 05 19.
Artículo en Inglés | MEDLINE | ID: mdl-32311315

RESUMEN

Proline-rich motifs (PRMs) are widely used for mediating protein-protein interactions with weak binding affinities. Because they are intrinsically disordered when unbound, conformational entropy plays a significant role for the binding. However, residue-level differences of the entropic contribution in the binding of different ligands remain not well understood. We use all-atom molecular dynamics simulation and the maximal information spanning tree formalism to analyze conformational entropy associated with the binding of two PRMs, one from the Abl kinase and the other from the nonstructural protein 1 of the 1918 Spanish influenza A virus, to the N-terminal SH3 (nSH3) domain of the CrkII protein. Side chains of the stably folded nSH3 experience more entropy change upon ligand binding than the backbone, whereas PRMs involve comparable but heterogeneous entropy changes among the backbone and side chains. In nSH3, two conserved nonpolar residues forming contacts with the PRM experience the largest side-chain entropy loss. In contrast, the C-terminal charged residues of PRMs that form polar contacts with nSH3 experience the greatest side-chain entropy loss, although their "fuzzy" nature is attributable to the backbone that remains relatively flexible. Thus, residues that form high-occupancy contacts between nSH3 and PRM do not reciprocally contribute to entropy loss. Furthermore, certain surface residues of nSH3 distal to the interface with PRMs gain entropy, indicating a nonlocal effect of ligand binding. Comparing between the PRMs from cAbl and nonstructural protein 1, the latter involves a larger side-chain entropy loss and forms more contacts with nSH3. Consistent with experiments, this indicates stronger binding of the viral ligand at the expense of losing the flexibility of side chains, whereas the backbone experiences less entropy loss. The entropy "hotspots" as identified in this study will be important for tuning the binding affinity of various ligands to a receptor.


Asunto(s)
Gripe Humana , Entropía , Humanos , Ligandos , Unión Proteica , Conformación Proteica , Proteínas Proto-Oncogénicas c-crk/metabolismo
5.
Biochem Biophys Res Commun ; 518(1): 178-182, 2019 10 08.
Artículo en Inglés | MEDLINE | ID: mdl-31420169

RESUMEN

Nonstructural protein 1 (NS1) is a multifunctional virulence factor of influenza virus. The effector domain (ED) of influenza viruses is capable of binding to a variety of host factors, however, the molecular basis of the interactions remains to be investigated. The isolated NS1-ED exists in equilibrium between the monomer and homodimer. Although the structural diversity of the dimer interface has been well-characterized, limited information is available regarding the internal conformational heterogeneity of the monomeric NS1-ED. Here, we present the solution NMR structure of the NS1-ED W187R of the 1918 influenza A virus, which caused the "Spanish flu." Structural plasticity is an essential property to understand the molecular mechanism by which NS1-ED interacts with multiple host proteins. Structural comparison with the NS1-ED from influenza A/Udorn/1972 (Ud) strain revealed a similar overall structure but a distinct conformational variation and flexibility. Our results suggest that conformational flexibility of the NS1-ED might differ depending on the influenza strain.


Asunto(s)
Virus de la Influenza A/metabolismo , Influenza Pandémica, 1918-1919 , Proteínas no Estructurales Virales/química , Modelos Moleculares , Proteínas Mutantes/química , Conformación Proteica , Soluciones , Proteínas no Estructurales Virales/metabolismo
6.
Gynecol Oncol ; 153(1): 3-12, 2019 04.
Artículo en Inglés | MEDLINE | ID: mdl-30642625

RESUMEN

OBJECTIVE: To compare survival outcomes of minimally invasive surgery (MIS) and conventional open surgery for radical hysterectomy (RH) among patients with early-stage cervical cancer (CC). METHODS: We retrospectively identified stage IB1-IIA2 CC patients who underwent either laparoscopic or open Type C RH between 2000 and 2018. Patients' clinicopathologic characteristics and survival outcomes were compared according to the surgical approach. For a more robust statistical analysis, we narrowed the study population down to the patients with stage IB1 who underwent pre-operative MRI. RESULTS: In total, 435 and 158 patients were assigned to open surgery and MIS groups, respectively. MIS group had significantly less parametrial invasion (6.3% vs. 15.4%; P = 0.004). Despite similar proportions of patients received adjuvant treatment, concurrent chemoradiation therapy was performed less frequently in MIS group. After a median follow up of 114.8 months, the groups showed similar overall survival; however, MIS group displayed poorer progression-free survival (PFS; 5-year rate, 78.5% vs. 89.7%; P < 0.001). Multivariate analyses identified MIS as an independent poor prognostic factor for PFS (adjusted HR, 2.883; 95% CI, 1.711-4.859; P < 0.001). Consistent results were observed among 349 patients with stage IB1: MIS was associated with higher recurrence rates (adjusted HR, 2.276; 95% CI, 1.039-4.986; P = 0.040). However, MIS did not influence PFS of stage IB1 patients with cervical mass size ≤2 cm on pre-operative MRI (adjusted HR, 1.146; 95% CI, 0.278-4.724; P = 0.850). CONCLUSIONS: Overall, MIS RH was associated with higher recurrence rates than open RH in patients with early-stage CC. However, MIS was not a poor prognostic factor among those with stage IB1 and cervical mass size ≤2 cm on pre-operative MRI.


Asunto(s)
Histerectomía/mortalidad , Procedimientos Quirúrgicos Mínimamente Invasivos/mortalidad , Neoplasias del Cuello Uterino/mortalidad , Neoplasias del Cuello Uterino/cirugía , Adulto , Estudios de Casos y Controles , Quimioradioterapia Adyuvante , Quimioterapia Adyuvante , Femenino , Humanos , Persona de Mediana Edad , Estadificación de Neoplasias , Pronóstico , Sistema de Registros , República de Corea/epidemiología , Estudios Retrospectivos , Resultado del Tratamiento , Neoplasias del Cuello Uterino/patología , Neoplasias del Cuello Uterino/terapia
7.
Int J Mol Sci ; 20(4)2019 Feb 20.
Artículo en Inglés | MEDLINE | ID: mdl-30791624

RESUMEN

Tumor-suppressive effects of resveratrol have been shown in various types of cancer. However, regulation of tumor microenvironment by resveratrol is still unclear. Recent findings suggest resveratrol can potentiate its tumor-suppressive effect through modulation of the signaling pathways of cellular components (fibroblasts, macrophages and T cells). Also, studies have shown that resveratrol can suppress malignant phenotypes of cancer cells acquired in response to stresses of the tumor microenvironment, such as hypoxia, oxidative stress and inflammation. We discuss the effects of resveratrol on cancer cells in stress environment of tumors as well as interactions between cancer cells and non-cancer cells in this review.


Asunto(s)
Antineoplásicos Fitogénicos/uso terapéutico , Suplementos Dietéticos , Neoplasias/tratamiento farmacológico , Neoplasias/patología , Resveratrol/uso terapéutico , Microambiente Tumoral/efectos de los fármacos , Inhibidores de la Angiogénesis/farmacología , Inhibidores de la Angiogénesis/uso terapéutico , Animales , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/farmacología , Biomarcadores , Humanos , Neoplasias/etiología , Neoplasias/metabolismo , Neovascularización Patológica/tratamiento farmacológico , Resveratrol/química , Resveratrol/farmacología , Transducción de Señal/efectos de los fármacos , Estrés Fisiológico/efectos de los fármacos
8.
Biophys J ; 114(6): 1313-1320, 2018 03 27.
Artículo en Inglés | MEDLINE | ID: mdl-29590589

RESUMEN

Many intrinsically disordered proteins (IDPs) form fuzzy complexes upon binding to their targets. Although many IDPs are weakly bound in fuzzy complexes, some IDPs form high-affinity complexes. One example is the nonstructural protein 1 (NS1) of the 1918 Spanish influenza A virus, which hijacks cellular CRKII through the strong binding affinity (Kd ∼10 nM) of its proline-rich motif (PRMNS1) to the N-terminal Src-homology 3 domain of CRKII. However, its molecular mechanism remains elusive. Here, we examine the interplay between structural disorder of a bound PRMNS1 and its long-range electrostatic interactions. Using x-ray crystallography and NMR spectroscopy, we found that PRMNS1 retains substantial conformational flexibility in the bound state. Moreover, molecular dynamics simulations showed that structural disorder of the bound PRMNS1 increases the number of electrostatic interactions and decreases the mean distances between the positively charged residues in PRMNS1 and the acidic residues in the N-terminal Src-homology 3 domain. These results are analyzed using a polyelectrostatic model. Our results provide an insight into the molecular recognition mechanism for a high-affinity fuzzy complex.


Asunto(s)
Proteínas Intrínsecamente Desordenadas/metabolismo , Secuencias de Aminoácidos , Proteínas Intrínsecamente Desordenadas/química , Simulación de Dinámica Molecular , Prolina , Unión Proteica , Dominios Proteicos , Electricidad Estática
9.
J Biol Chem ; 292(47): 19226-19237, 2017 11 24.
Artículo en Inglés | MEDLINE | ID: mdl-28972189

RESUMEN

Lipopolysaccharide, the outer cell-wall component of Gram-negative bacteria, has been shown to be important for symbiotic associations. We recently reported that the lipopolysaccharide O-antigen of Burkholderia enhances the initial colonization of the midgut of the bean bug, Riptortus pedestris However, the midgut-colonizing Burkholderia symbionts lack the O-antigen but display the core oligosaccharide on the cell surface. In this study, we investigated the role of the core oligosaccharide, which directly interacts with the host midgut, in the Riptortus-Burkholderia symbiosis. To this end, we generated the core oligosaccharide mutant strains, ΔwabS, ΔwabO, ΔwaaF, and ΔwaaC, and determined the chemical structures of their oligosaccharides, which exhibited different compositions. The symbiotic properties of these mutant strains were compared with those of the wild-type and O-antigen-deficient ΔwbiG strains. Upon introduction into Riptortus via the oral route, the core oligosaccharide mutant strains exhibited different rates of colonization of the insect midgut. The symbiont titers in fifth-instar insects revealed significantly reduced population sizes of the inner core oligosaccharide mutant strains ΔwaaF and ΔwaaC These two strains also negatively affected host growth rate and fitness. Furthermore, R. pedestris individuals colonized with the ΔwaaF and ΔwaaC strains were vulnerable to septic bacterial challenge, similar to insects without a Burkholderia symbiont. Taken together, these results suggest that the core oligosaccharide from Burkholderia symbionts plays a critical role in maintaining a proper symbiont population and in supporting the beneficial effects of the symbiont on its host in the Riptortus-Burkholderia symbiosis.


Asunto(s)
Burkholderia/fisiología , Tracto Gastrointestinal/crecimiento & desarrollo , Heterópteros/crecimiento & desarrollo , Oligosacáridos/metabolismo , Simbiosis/fisiología , Animales , Burkholderia/genética , Tracto Gastrointestinal/metabolismo , Tracto Gastrointestinal/microbiología , Heterópteros/genética , Heterópteros/microbiología , Mutación , Antígenos O/metabolismo
10.
Biophys J ; 112(9): 1797-1806, 2017 May 09.
Artículo en Inglés | MEDLINE | ID: mdl-28494951

RESUMEN

The N-terminal domain of L9 (NTL9) is a 56-residue mixed α-ß protein that lacks disulfides, does not bind cofactors, and folds reversibly. NTL9 has been widely used as a model system for experimental and computational studies of protein folding and for investigations of the unfolded state. The role of side-chain interactions in the folding of NTL9 is probed by mutational analysis. ϕ-values, which represent the ratio of the change in the log of the folding rate upon mutation to the change in the log of the equilibrium constant for folding, are reported for 25 point mutations and 15 double mutants. All ϕ-values are small, with an average over all sites probed of only 0.19 and a largest value of 0.4. The effect of modulating unfolded-state interactions is studied by measuring ϕ-values in second- site mutants and under solvent conditions that perturb unfolded-state energetics in a defined way. Neither of these alterations significantly affects the distribution of ϕ-values. The results, combined with those of earlier studies that probe the role of hydrogen-bond formation in folding and the burial of surface area, reveal that the transition state for folding contains extensive backbone structure and buries a significant fraction of hydrophobic surface area, but lacks well developed side-chain-side-chain interactions. The folding transition state for NTL9 does not contain a specific "nucleus" consisting of a few key residues; rather, it involves extensive backbone hydrogen bonding and partially formed structure delocalized over almost the entire domain. The potential generality of these observations is discussed.


Asunto(s)
Pliegue de Proteína , Proteínas Ribosómicas/metabolismo , Secuencia de Aminoácidos , Enlace de Hidrógeno , Cinética , Modelos Moleculares , Mutación , Estructura Secundaria de Proteína , Proteínas Ribosómicas/química , Proteínas Ribosómicas/genética , Termodinámica
11.
Biochem Biophys Res Commun ; 484(1): 21-26, 2017 02 26.
Artículo en Inglés | MEDLINE | ID: mdl-28111343

RESUMEN

Biological functions of intrinsically disordered proteins (IDPs), and proteins containing intrinsically disordered regions (IDRs) are often mediated by short linear motifs, like proline-rich motifs (PRMs). Upon binding to their target proteins, IDPs undergo a disorder-to-order transition which is accompanied by a large conformational entropy penalty. Hence, the molecular mechanisms underlying control of conformational entropy are critical for understanding the binding affinity and selectivity of IDPs-mediated protein-protein interactions (PPIs). Here, we investigated the backbone conformational entropy change accompanied by binding of the N-terminal SH3 domain (nSH3) of CrkII and PRM derived from guanine nucleotide exchange factor 1 (C3G). In particular, we focused on the estimation of conformational entropy change of disordered PRM upon binding to the nSH3 domain. Quantitative characterization of conformational dynamics of disordered peptides like PRMs is limited. Hence, we combined various methods, including NMR model-free analysis, δ2D, DynaMine, and structure-based calculation of entropy loss. This study demonstrates that the contribution of backbone conformational entropy change is significant in the PPIs mediated by IDPs/IDRs.


Asunto(s)
Entropía , Proteínas Intrínsecamente Desordenadas/química , Prolina/química , Termodinámica , Dominios Homologos src , Ligandos , Espectroscopía de Resonancia Magnética , Unión Proteica , Conformación Proteica
12.
Arch Virol ; 162(4): 1129-1139, 2017 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-28028618

RESUMEN

Klebsiella is a genus of well-known opportunistic human pathogens that are associated with diabetes mellitus and chronic pulmonary obstruction; however, this pathogen is often resistant to multiple drugs. To control this pathogen, two Klebsiella-infecting phages, K. oxytoca phage PKO111 and K. pneumoniae phage PKP126, were isolated from a sewage sample. Analysis of their host range revealed that they infect K. pneumoniae and K. oxytoca, suggesting host specificity for members of the genus Klebsiella. Stability tests confirmed that the phages are stable under various temperature (4 to 60 °C) and pH (3 to 11) conditions. A challenge assay showed that PKO111 and PKP126 inhibit growth of their host strains by 2 log and 4 log, respectively. Complete genome sequencing of the phages revealed that their genome sizes are quite different (168,758 bp for PKO111 and 50,934 bp for PKP126). Their genome annotation results showed that they have no human virulence-related genes, an important safety consideration. In addition, no lysogen-formation gene cluster was detected in either phage genome, suggesting that they are both virulent phages in their bacterial hosts. Based on these results, PKO111 and PKP126 may be good candidates for development of biocontrol agents against members of the genus Klebsiella for therapeutic purposes. A comparative analysis of tail-associated gene clusters of PKO111 and PKP126 revealed relatively low homology, suggesting that they might differ in the way they recognize and infect their specific hosts.


Asunto(s)
Bacteriófagos/aislamiento & purificación , Bacteriófagos/fisiología , Genoma Viral , Infecciones por Klebsiella/microbiología , Klebsiella oxytoca/virología , Klebsiella pneumoniae/virología , Bacteriófagos/clasificación , Bacteriófagos/genética , Humanos , Klebsiella oxytoca/fisiología , Klebsiella pneumoniae/fisiología , Sistemas de Lectura Abierta , Filogenia , Proteínas Virales/genética
13.
Nanotechnology ; 28(25): 255401, 2017 Jun 23.
Artículo en Inglés | MEDLINE | ID: mdl-28548050

RESUMEN

Silicon (Si) has a large theoretical capacity of 4200 mAhg-1 and has great potential as a high-performance anode material for Li ion batteries (LIBs). Meanwhile, nanostructures can exploit the potential of Si and, accordingly, many zero-dimensional (0D) and one-dimensional (1D) Si nanostructures have been studied. Herein, we report on two-dimensional (2D) Si nanostructures, Si nanosheets (SiNSs), as anodes for LIBs. These 2D Si nanostructures, with a thickness as low 5 nm and widths of several micrometers, show reversible crystalline-amorphous phase transformations with the lithi-/delithiation by the dimensionality of morphology and large surface area. The reversible crystalline-amorphous phase transformation provides a structural stability of Li+ insertions and makes SiNSs promising candidates for reliable high-performance LIBs anode materials.

14.
Proc Natl Acad Sci U S A ; 111(33): 12079-84, 2014 Aug 19.
Artículo en Inglés | MEDLINE | ID: mdl-25099351

RESUMEN

Unfolded and partially unfolded proteins participate in a wide range of biological processes from pathological aggregation to the regulation of normal cellular activity. Unfolded states can be populated under strongly denaturing conditions, but the ensemble which is relevant for folding, stability, and aggregation is that populated under physiological conditions. Characterization of nonnative states is critical for the understanding of these processes, yet comparatively little is known about their energetics and their structural propensities under native conditions. The standard view is that energetically significant coupled interactions involving multiple residues are generally not present in the denatured state ensemble (DSE) or in intrinsically disordered proteins. Using the N-terminal domain of the ribosomal protein L9, a small α-ß protein, as an experimental model system, we demonstrate that networks of energetically significant, coupled interactions can form in the DSE of globular proteins, and can involve residues that are distant in sequence and spatially well separated in the native structure. X-ray crystallography, NMR, dynamics studies, native state pKa measurements, and thermodynamic analysis of more than 25 mutants demonstrate that residues are energetically coupled in the DSE. Altering these interactions by mutation affects the stability of the domain. Mutations that alter the energetics of the DSE can impact the analysis of cooperativity and folding, and may play a role in determining the propensity to aggregate.


Asunto(s)
Proteínas/química , Cristalografía , Mutación , Resonancia Magnética Nuclear Biomolecular , Desplegamiento Proteico , Proteínas/genética , Termodinámica
15.
Biophys J ; 111(9): 1843-1853, 2016 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-27806266

RESUMEN

The interaction between CrkII and cAbl is implicated in diverse cellular processes. This interaction starts with the binding of the N-terminal Src homology 3 (nSH3) domain of CrkII to the proline-rich motifs of cAbl (PRMscAbl). Despite its critical importance, the detailed binding mechanism between the nSH3 domain and PRMs remains elusive. In this study, we used nuclear magnetic resonance Carr-Purcell-Meiboom-Gill relaxation dispersion experiment to study the binding kinetics between the nSH3 domain of CrkII and PRMscAbl. Our results highlight that the nSH3 domain binds to three PRMscAbl with very high on- and off-rate constants, indicating the transient nature of the binding. To further characterize the binding transition state, we conducted the Eyring and linear free energy relationship analyses using temperature-dependent kinetic data. These data indicate that the binding transition state of the nSH3 domain and PRM is accompanied by small activation enthalpy, owing to partial desolvation of the transition state. These results also highlight the similarity between the transition and free states, in terms of structure and energetics. Although the binding of the nSH3 domain and PRM displays the features consistent with a diffusion-limited process within our experimental conditions, further tests are necessary to determine if the binding is a true diffusion-limited process.


Asunto(s)
Prolina , Proteínas Proto-Oncogénicas c-abl/química , Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Proto-Oncogénicas c-crk/química , Proteínas Proto-Oncogénicas c-crk/metabolismo , Dominios Homologos src , Secuencias de Aminoácidos , Secuencia de Aminoácidos , Cinética , Modelos Moleculares , Unión Proteica , Temperatura
16.
Biophys J ; 110(12): 2630-2641, 2016 Jun 21.
Artículo en Inglés | MEDLINE | ID: mdl-27332121

RESUMEN

The N-terminal Src homology 3 (nSH3) domain of a signaling adaptor protein, CT-10 regulator of kinase II (CrkII), recognizes proline-rich motifs (PRMs) of binding partners, such as cAbl kinase. The interaction between CrkII and cAbl kinase is involved in the regulation of cell spreading, microbial pathogenesis, and cancer metastasis. Here, we report the detailed biophysical characterizations of the interactions between the nSH3 domain of CrkII and PRMs in cAbl. We identified that the nSH3 domain of CrkII binds to three PRMs in cAbl with virtually identical affinities. Structural studies, by using x-ray crystallography and NMR spectroscopy, revealed that the binding modes of all three nSH3:PRM complexes are highly similar to each other. Van 't Hoff analysis revealed that nSH3:PRM interaction is associated with favorable enthalpy and unfavorable entropy change. The combination of experimentally determined thermodynamic parameters, structure-based calculations, and (15)N NMR relaxation analysis highlights the energetic contribution of conformational entropy change upon the complex formation, and water molecules structured in the binding interface of the nSH3:PRM complex. Understanding the molecular basis of nSH3:PRM interaction will provide, to our knowledge, new insights for the rational design of small molecules targeting the interaction between CrkII and cAbl.


Asunto(s)
Proteínas Proto-Oncogénicas c-abl/metabolismo , Proteínas Proto-Oncogénicas c-crk/metabolismo , Dominios Homologos src , Simulación por Computador , Cristalografía por Rayos X , Escherichia coli , Humanos , Modelos Moleculares , Método de Montecarlo , Resonancia Magnética Nuclear Biomolecular , Prolina/metabolismo , Unión Proteica , Multimerización de Proteína , Proteínas Proto-Oncogénicas c-abl/genética , Proteínas Proto-Oncogénicas c-crk/genética , Termodinámica , Agua/metabolismo , Dominios Homologos src/genética
17.
J Biol Chem ; 290(34): 21042-21053, 2015 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-26116716

RESUMEN

The molecular characterization of symbionts is pivotal for understanding the cross-talk between symbionts and hosts. In addition to valuable knowledge obtained from symbiont genomic studies, the biochemical characterization of symbionts is important to fully understand symbiotic interactions. The bean bug (Riptortus pedestris) has been recognized as a useful experimental insect gut symbiosis model system because of its cultivatable Burkholderia symbionts. This system is greatly advantageous because it allows the acquisition of a large quantity of homogeneous symbionts from the host midgut. Using these naïve gut symbionts, it is possible to directly compare in vivo symbiotic cells with in vitro cultured cells using biochemical approaches. With the goal of understanding molecular changes that occur in Burkholderia cells as they adapt to the Riptortus gut environment, we first elucidated that symbiotic Burkholderia cells are highly susceptible to purified Riptortus antimicrobial peptides. In search of the mechanisms of the increased immunosusceptibility of symbionts, we found striking differences in cell envelope structures between cultured and symbiotic Burkholderia cells. The bacterial lipopolysaccharide O antigen was absent from symbiotic cells examined by gel electrophoretic and mass spectrometric analyses, and their membranes were more sensitive to detergent lysis. These changes in the cell envelope were responsible for the increased susceptibility of the Burkholderia symbionts to host innate immunity. Our results suggest that the symbiotic interactions between the Riptortus host and Burkholderia gut symbionts induce bacterial cell envelope changes to achieve successful gut symbiosis.


Asunto(s)
Burkholderia/química , Pared Celular/química , Heterópteros/microbiología , Antígenos O/química , Simbiosis , Animales , Péptidos Catiónicos Antimicrobianos/farmacología , Burkholderia/efectos de los fármacos , Burkholderia/metabolismo , Burkholderia/fisiología , Membrana Celular/química , Membrana Celular/efectos de los fármacos , Membrana Celular/metabolismo , Pared Celular/efectos de los fármacos , Pared Celular/metabolismo , Tracto Gastrointestinal/efectos de los fármacos , Tracto Gastrointestinal/inmunología , Tracto Gastrointestinal/metabolismo , Tracto Gastrointestinal/microbiología , Heterópteros/inmunología , Heterópteros/metabolismo , Antígenos O/metabolismo
18.
Neuroimage ; 110: 60-77, 2015 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-25638756

RESUMEN

The results of brain connectivity analysis using reconstructed source time courses derived from EEG and MEG data depend on a number of algorithmic choices. While previous studies have investigated the influence of the choice of source estimation method or connectivity measure, the effects of the head modeling errors or simplifications have not been studied sufficiently. In the present simulation study, we investigated the influence of particular properties of the head model on the reconstructed source time courses as well as on source connectivity analysis in EEG and MEG. Therefore, we constructed a realistic head model and applied the finite element method to solve the EEG and MEG forward problems. We considered the distinction between white and gray matter, the distinction between compact and spongy bone, the inclusion of a cerebrospinal fluid (CSF) compartment, and the reduction to a simple 3-layer model comprising only the skin, skull, and brain. Source time courses were reconstructed using a beamforming approach and the source connectivity was estimated by the imaginary coherence (ICoh) and the generalized partial directed coherence (GPDC). Our results show that in both EEG and MEG, neglecting the white and gray matter distinction or the CSF causes considerable errors in reconstructed source time courses and connectivity analysis, while the distinction between spongy and compact bone is just of minor relevance, provided that an adequate skull conductivity value is used. Large inverse and connectivity errors are found in the same regions that show large topography errors in the forward solution. Moreover, we demonstrate that the very conservative ICoh is relatively safe from the crosstalk effects caused by imperfect head models, as opposed to the GPDC.


Asunto(s)
Electroencefalografía/métodos , Cabeza/anatomía & histología , Magnetoencefalografía/métodos , Vías Nerviosas/anatomía & histología , Algoritmos , Mapeo Encefálico , Líquido Cefalorraquídeo , Humanos , Procesamiento de Imagen Asistido por Computador , Modelos Anatómicos , Modelos Neurológicos , Cráneo/anatomía & histología
19.
Neuroimage ; 100: 590-607, 2014 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-24971512

RESUMEN

For accurate EEG/MEG source analysis it is necessary to model the head volume conductor as realistic as possible. This includes the distinction of the different conductive compartments in the human head. In this study, we investigated the influence of modeling/not modeling the conductive compartments skull spongiosa, skull compacta, cerebrospinal fluid (CSF), gray matter, and white matter and of the inclusion of white matter anisotropy on the EEG/MEG forward solution. Therefore, we created a highly realistic 6-compartment head model with white matter anisotropy and used a state-of-the-art finite element approach. Starting from a 3-compartment scenario (skin, skull, and brain), we subsequently refined our head model by distinguishing one further of the above-mentioned compartments. For each of the generated five head models, we measured the effect on the signal topography and signal magnitude both in relation to a highly resolved reference model and to the model generated in the previous refinement step. We evaluated the results of these simulations using a variety of visualization methods, allowing us to gain a general overview of effect strength, of the most important source parameters triggering these effects, and of the most affected brain regions. Thereby, starting from the 3-compartment approach, we identified the most important additional refinement steps in head volume conductor modeling. We were able to show that the inclusion of the highly conductive CSF compartment, whose conductivity value is well known, has the strongest influence on both signal topography and magnitude in both modalities. We found the effect of gray/white matter distinction to be nearly as big as that of the CSF inclusion, and for both of these steps we identified a clear pattern in the spatial distribution of effects. In comparison to these two steps, the introduction of white matter anisotropy led to a clearly weaker, but still strong, effect. Finally, the distinction between skull spongiosa and compacta caused the weakest effects in both modalities when using an optimized conductivity value for the homogenized compartment. We conclude that it is highly recommendable to include the CSF and distinguish between gray and white matter in head volume conductor modeling. Especially for the MEG, the modeling of skull spongiosa and compacta might be neglected due to the weak effects; the simplification of not modeling white matter anisotropy is admissible considering the complexity and current limitations of the underlying modeling approach.


Asunto(s)
Electroencefalografía/métodos , Sustancia Gris/anatomía & histología , Imagen por Resonancia Magnética/métodos , Magnetoencefalografía/métodos , Cráneo/anatomía & histología , Sustancia Blanca/anatomía & histología , Adulto , Simulación por Computador , Electroencefalografía/normas , Humanos , Imagen por Resonancia Magnética/normas , Magnetoencefalografía/normas , Masculino , Modelos Neurológicos
20.
J Am Chem Soc ; 136(46): 16116-9, 2014 Nov 19.
Artículo en Inglés | MEDLINE | ID: mdl-25364815

RESUMEN

We have conducted extensive theoretical and experimental investigations to unravel the origin of the electrochemical properties of hybrid Mg(2+)/Li(+) rechargeable batteries at the atomistic and macroscopic levels. By revealing the thermodynamics of Mg(2+) and Li(+) co-insertion into the Mo6S8 cathode host using density functional theory calculations, we show that there is a threshold Li(+) activity for the pristine Mo6S8 cathode to prefer lithiation instead of magnesiation. By precisely controlling the insertion chemistry using a dual-salt electrolyte, we have enabled ultrafast discharge of our battery by achieving 93.6% capacity retention at 20 C and 87.5% at 30 C, respectively, at room temperature.

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