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1.
Biomed Mater ; 19(3)2024 Apr 29.
Artigo em Inglês | MEDLINE | ID: mdl-38682577

RESUMO

Fabrication of gold nanoparticles (GNPs) with phytochemicals is an emerging green nanotechnology approach with therapeutic implications. Garlic, known for its culinary and medicinal properties, has been extensively investigated for its anticancer properties. Here, we report a method to substantially enhance the antiproliferative potency of garlic by functionalizing its phytochemicals to GNPs and demonstrate a possible mechanism of action of these nanoparticles in the triple-negative breast cancer cell line, MDA-MB-231. Garlic gold nanoparticles (As-GNPs) were synthesized using garlic extract (As-EX) and gold chloride and characterized using a variety of spectroscopy techniques, and transmission electron microscopy (TEM). Compared to As-EX, which has a negligible effect on the viability of the cells, As-GNPs inhibited cell viability with an IC50of 0.310 ± 0.04 mg ml-1and strongly inhibited the clonogenic and migratory propensities of these cells. As indicated by TEM, the As-GNPs entered the cells via endocytosis and dispersed in the cellular milieu. Since tubulin, the protein involved in cell division, is a verified target for several antiproliferative drugs, we next examined whether the As-GNPs interact with this protein. The As-GNPs showed concentration-dependent binding to purified tubulin, slightly but consistently perturbing its secondary helical integritywithout grossly damaging the tertiary structure of the protein or the net polymer mass of the microtubules, as indicated by a tryptophan-quenching assay, far UV-circular dichroism spectroscopy, anilinonaphthalene sulfonate-binding assay, and polymer mass analysis, respectively. In cells, As-GNPs killed the cancer cells without cell cycle arrest, as evidenced by flow cytometry.


Assuntos
Proliferação de Células , Sobrevivência Celular , Alho , Ouro , Nanopartículas Metálicas , Neoplasias de Mama Triplo Negativas , Humanos , Alho/química , Ouro/química , Nanopartículas Metálicas/química , Neoplasias de Mama Triplo Negativas/tratamento farmacológico , Neoplasias de Mama Triplo Negativas/metabolismo , Neoplasias de Mama Triplo Negativas/patologia , Proliferação de Células/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Compostos Fitoquímicos/farmacologia , Compostos Fitoquímicos/química , Extratos Vegetais/química , Extratos Vegetais/farmacologia , Feminino , Antineoplásicos/farmacologia , Antineoplásicos/química , Tubulina (Proteína)/metabolismo , Movimento Celular/efeitos dos fármacos , Microscopia Eletrônica de Transmissão
2.
Structure ; 32(6): 690-705.e6, 2024 Jun 06.
Artigo em Inglês | MEDLINE | ID: mdl-38565139

RESUMO

The centromere is epigenetically marked by a histone H3 variant-CENP-A. The budding yeast CENP-A called Cse4, consists of an unusually long N-terminus that is known to be involved in kinetochore assembly. Its disordered chaperone, Scm3 is responsible for the centromeric deposition of Cse4 as well as in the maintenance of a segregation-competent kinetochore. In this study, we show that the Cse4 N-terminus is intrinsically disordered and interacts with Scm3 at multiple sites, and the complex does not gain any substantial structure. Additionally, the complex forms a synergistic association with an essential inner kinetochore component (Ctf19-Mcm21-Okp1-Ame1), and a model has been suggested to this effect. Thus, our study provides mechanistic insights into the Cse4 N-terminus-chaperone interaction and also illustrates how intrinsically disordered proteins mediate assembly of complex multiprotein networks, in general.


Assuntos
Proteínas Cromossômicas não Histona , Proteínas de Ligação a DNA , Cinetocoros , Ligação Proteica , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Cinetocoros/metabolismo , Cinetocoros/química , Proteínas Cromossômicas não Histona/metabolismo , Proteínas Cromossômicas não Histona/química , Proteínas Cromossômicas não Histona/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Saccharomyces cerevisiae/metabolismo , Chaperonas Moleculares/metabolismo , Chaperonas Moleculares/química , Modelos Moleculares , Proteínas Intrinsicamente Desordenadas/metabolismo , Proteínas Intrinsicamente Desordenadas/química , Proteína Centromérica A/metabolismo , Proteína Centromérica A/química , Sítios de Ligação , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/química , Proteínas do Citoesqueleto , Proteínas Associadas aos Microtúbulos
3.
Biomater Adv ; 153: 213542, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37418933

RESUMO

Type 2 diabetes mellitus (T2DM) is a serious and alarming disease attracting widespread attention. It is not a single metabolic disease; over time, it leads to serious disorders, namely, diabetic nephropathy, neuropathy, retinopathy and several cardiovascular, hepatocellular complications. The increase in T2DM cases in recent times has attracted significant attention. Currently, the medications available have side effects, and injectables are painful, causing trauma to the patients. Therefore, it is imperative to come up with oral delivery. In this background we report here a nanoformulation carrying natural small molecule Myricetin (MYR) encapsulated within Chitosan nanoparticles (CHT-NPs). MYR-CHT-NPs were prepared by ionic gelation method and evaluated using different characterization techniques. The in vitro release of MYR from CHT NPs in different physiological media showed pH dependence. in vivo pharmacodynamic study followed by oral administration in Albino Wistar rats showed better glycaemic control than existing drug. Further, the optimized nanoparticles also exhibited controlled increase in weight as compared to Metformin. The biochemistry profile of rats treated with nanoformulation reduced the levels of several pathological biomarkers, indicating additional benefits of MYR. Histopathological images exhibited no toxicity or changes in the major organs section in contrast to normal control, suggesting safe oral administration of the encapsulated MYR. Thus, we conclude that MYR-CHT-NPs represent an attractive delivery vehicle in improving the blood glucose level with controlled weight and have the potential to be safely administered orally for the management of T2DM.


Assuntos
Quitosana , Diabetes Mellitus Tipo 2 , Nanopartículas , Ratos , Animais , Diabetes Mellitus Tipo 2/tratamento farmacológico , Quitosana/química , Flavonoides/farmacologia , Flavonoides/uso terapêutico , Nanopartículas/química , Ratos Wistar
4.
Chembiochem ; 24(5): e202200682, 2023 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-36597005

RESUMO

Ultraviolet C (UV-C) radiation induces apoptosis in mammalian cells via the mitochondrion-mediated pathway. The Bcl-2 family of proteins are the regulators of the mitochondrial pathway of apoptosis and appears responsive to UV-C radiation. It is unknown how the structure and, effectively, the function of these proteins are directly impacted by UV-C exposure. Here, we present the effect of UV-C irradiation on the structure and function of pro-apoptotic Bid-FL and anti-apoptotic Bcl-xlΔC proteins. Using a variety of biophysical tools, we show that, following UV-C irradiation, the structures of Bcl-xlΔC and Bid-FL are irreversibly altered. Bcl-xLΔC is found to be more sensitive to UV stress than Bid-FL Interestingly, UV-C exposure shows dramatic chemical shift perturbations in consequence of dramatic structural perturbations (α-helix to ß-sheet) in the BH3- binding region, a crucial segment of Bcl-xlΔC. Furter it has been shown that UV-exposed Bcl-xlΔC has reduced efficacy of its interactions with pro-apoptotic tBid.


Assuntos
Proteínas Reguladoras de Apoptose , Apoptose , Animais , Proteína bcl-X/metabolismo , Proteína Agonista de Morte Celular de Domínio Interatuante com BH3/metabolismo , Mitocôndrias/metabolismo , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , Mamíferos/metabolismo
5.
RSC Adv ; 12(55): 35770-35777, 2022 Dec 12.
Artigo em Inglês | MEDLINE | ID: mdl-36545068

RESUMO

The accumulation of the intrinsically disordered protein alpha-synuclein (αSyn) in the form of insoluble fibrillar aggregates in the central nervous system is linked to a variety of neurodegenerative disorders such as Parkinson's disease, Lewy body dementia, and multiple system atrophy. Here we show that Pyrogallol, Corilagin and Chebulagic acid, compounds containing a different number of catechol rings, are independently capable of delaying and reducing the extent of αSyn fibrillization. The efficiency of inhibition was found to correlate with the number of catechol rings. Further, our NMR studies reveal that these compounds interact with the N-terminal region of αSyn which is unstructured even in the fibrillar form of the protein and is known as the "fuzzy coat" of fibrils. Thus, Corilagin and Chebulagic acid target the fuzzy coat of αSyn and not the amyloid core which is a common target for the inhibition of protein fibrillization. Our results indicate that the N-terminus also plays a key role in the fibrillization of αSyn.

6.
Int J Clin Pediatr Dent ; 15(1): 121-123, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35528488

RESUMO

Amelogenesis imperfecta (AI) is an inherited dental condition affecting enamel, which can result in significant tooth discoloration and enamel breakdown, requiring lifelong dental care. Distal renal tubular acidosis (dRTA) is a condition in which the kidneys are unable to acidify the urine to a pH < 5.5 in the presence of systemic metabolic acidosis. Management of AI and dRTA patients requires both medical and dental expertise to achieve long-term successful results. The aim of this paper is to present the dental management of a child with AI and dRTA. How to cite this article: Nadaf N, Krishnapriya V, Chandra A, et al. Amelogenesis Imperfecta and Distal Renal Tubular Acidosis. Int J Clin Pediatr Dent 2022;15(1):121-123.

7.
J Magn Reson ; 337: 107165, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-35202919

RESUMO

We present here a novel protocol for quantitating changes in the NMR spectra, which is based on Mahalanobis statistics. In a two dimensional NMR spectrum, the various peaks are taken to represent a distribution, and the two chemical shifts along the orthogonal axes and the peak intensities constitute three observables. All these observables vary in a correlated manner. Taking account of these, the Mahalanobis distance (MD) reflects the distance of any chosen peak from the centre of the distribution. For quantitating changes in a particular spectrum (say A) with N peaks (altered protein NMR spectrum) with respect to a reference spectrum (say B) with M peaks (original protein NMR spectrum), a composite spectrum with N + M peaks is generated. A one-to-one correspondence between N MD values considering all the N peaks in A and the same N peaks in the composite spectrum (A + B) is calculated. The MD distance of corresponding peaks in two different distributions can be correlated to assess the changes in the spectra during the course of a biological phenomenon, or as a result of biomolecular interactions. We have demonstrated these ideas, first, using the 1H-15N HSQC spectrum of Ubiquitin, and then application of these has been demonstrated for monitoring progression of fibrillation of the protein α-Synuclein, in absence and presence of safranal, a known inhibitor of fibrillation of the protein. The method is in general applicable to multidimensional NMR spectra, does not require extensive data collection, and allows quantitative assessment of spectral changes via a single parameter. We believe that the method will have wide ranging applications to monitor many biological phenomena, and will also be useful in an industrial environment for mass comparison of molecules in a rapid manner.


Assuntos
Proteínas , Ubiquitina , Imageamento por Ressonância Magnética , Espectroscopia de Ressonância Magnética/métodos , Proteínas/química
8.
Curr Res Food Sci ; 5: 272-277, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35141528

RESUMO

Nuclear magnetic resonance (NMR) is a powerful analytical tool which can be used for authenticating honey, at chemical constituent levels by enabling identification and quantification of the spectral patterns. However, it is still challenging, as it may be a person-centric analysis or a time-consuming process to analyze many honey samples in a limited time. Hence, automating the NMR spectral analysis of honey with the supervised machine learning models accelerates the analysis process and especially food chemistry researcher or food industry with non-NMR experts would benefit immensely from such advancements. Here, we have successfully demonstrated this technology by considering three major sugar adulterants, i.e., brown rice syrup, corn syrup, and jaggery syrup, in honey at varying concentrations. The necessary supervised machine learning classification analysis is performed by using logistic regression, deep learning-based neural network, and light gradient boosting machines schemes.

9.
Proteins ; 90(2): 455-464, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34528298

RESUMO

Apoptosis is a naturally occurring process during the growth and development of multicellular organisms and is increasingly active during times of cellular stress such as in response to intracellular DNA damage when removal of the host cell is paramount to prevent cancer. Unfortunately, once formed, cancer cells become impervious to apoptosis, creating a desperate need to identify an approach to induce apoptosis in these cells. An attractive option is to focus efforts on developing and locating compounds which activate apoptosis using natural compounds. Curcumin is a natural component in turmeric and is well-known for its pharmacological effects in preventing and combating many ailments and has been shown to decrease the rapid proliferation of a wide variety of tumor cells. However, to date, the apoptotic intermediates and interactions through which curcumin exerts its cytotoxic effects are unknown. Motivated by reports linking the intracellular modulation of the concentrations of Bid and Bcl-xL, following curcumin administration to cancer cells, we set out to probe for potential intermolecular interactions of these proteins with curcumin. Using several biophysical techniques, most notably, fluorescence, circular dichroism and nuclear magnetic resonance spectroscopy, we reveal binding interactions of curcumin with both Bcl-xLΔC and full-length Bid (Bid-FL) and prove that this binding is hydrophobically driven and localized to well-known functional regions of each protein. Specifically, our NMR studies show that while Bid-FL interacts with curcumin through its hydrophobic and pore forming helices (α6-α7), Bcl-xLΔC interacts with curcumin via its BH3 binding pocket (α2-α3-α4-α5), a critical region for mediating apoptosis.


Assuntos
Proteína Agonista de Morte Celular de Domínio Interatuante com BH3/metabolismo , Curcumina/farmacologia , Neoplasias/tratamento farmacológico , Proteína bcl-X/metabolismo , Apoptose , Humanos
10.
Biophys Chem ; 281: 106742, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34922214

RESUMO

Intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs) are proteins and protein segments that usually do not acquire well-defined folded structures even under physiological conditions. They are abundantly present and challenge the "one sequence-one structure-one function" theory due to a lack of stable secondary and/or tertiary structure. Due to conformational flexibility, IDPs/IDPRs can bind with multiple interacting partners with high-specificity and low-affinity and perform essential biological functions associated with signalling, recognition and regulation. Mis-functioning and mis-regulation of IDPs and IDPRs causes disorder in disordered proteins and disordered protein segments which results in numerous human diseases, such as cancer, Parkinson's disease (PD), Alzheimer's disease (AD), diabetes, metabolic disorders, systemic disorders and so on. Due to the strong connection of IDPs/IDPRs with human diseases they are considered potentential targets for drug therapy. Since they disobey the "one sequence-one structure-one function" concept, IDPs/IDPRs are complex systems for drug targeting. This review summarises various protein disorder diseases and different methods for therapeutic targeting of disordered proteins/segments. Targeting IDPs/IDPRs for diseases will open up a new era of rational drug design and drug discovery.


Assuntos
Doença de Alzheimer , Proteínas Intrinsicamente Desordenadas , Desenho de Fármacos , Descoberta de Drogas/métodos , Humanos , Proteínas Intrinsicamente Desordenadas/química , Conformação Proteica
12.
Sci Rep ; 11(1): 23270, 2021 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-34857812

RESUMO

Crystallins are ubiquitous, however, prevalence is seen in eye lens. Eye lens crystallins are long-lived and structural intactness is required for maintaining lens transparency and protein solubility. Mutations in crystallins often lead to cataract. In this study, we performed mutations at specific sites of M-crystallin, a close homologue of eye lens crystallin and studied by using replica exchange molecular dynamics simulation with generalized Born implicit solvent model. Mutations were made on the Ca2+ binding residues (K34D and S77D) and in the hydrophobic core (W45R) which is known to cause congenital cataract in homologous γD-crystallin. The chosen mutations caused large motion of the N-terminal Greek key, concomitantly broke the interlocking Greek keys interactions and perturbed the compact core resulting in several folded and partially unfolded states. Partially unfolded states exposed large hydrophobic patches that could act as precursors for self-aggregation. Accumulation of such aggregates is the potential cause of cataract in homologous eye lens crystallins.


Assuntos
Catarata/genética , Cristalinas/genética , Simulação de Dinâmica Molecular , Mutação , Cristalinas/metabolismo , Humanos , Interações Hidrofóbicas e Hidrofílicas , Cristalino/metabolismo , Dobramento de Proteína
13.
Int J Biol Macromol ; 182: 1278-1291, 2021 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-33991558

RESUMO

The aggregation of α-synuclein is linked to neurological disorders, and of these, Parkinson's disease (PD) is among the most widely studied. In this background, we have investigated here the effects of three α, ß-unsaturated carbonyl based plant metabolites, daidzein, fisetin and scopoletin on α-Syn aggregation. The ThT and light scattering kinetics studies establish that these compounds have ability to inhibit α-Syn fibrillation to different extents; this is confirmed by TEM studies. It is pertinent to note here that daidzein and scopoletin have been predicted to be able to cross the blood brain barrier. ANS binding assays demonstrate that the compounds interfere in the hydrophobic interactions. The tyrosine quenching, molecular docking and MD simulation studies showed that the compounds bind with α-Syn and provide structural rigidity which delays onset of structural transitions, which is confirmed by CD spectroscopy. The results obtained here throw light on the mechanisms underlying inhibition of α-Syn fibrillation by these compounds. Thus, the current work has significant therapeutic implications for identifying plant based potent therapeutic molecules for PD and other synucleinopathies, an area which needs extensive exploration.


Assuntos
Flavonóis/farmacologia , Isoflavonas/farmacologia , Metaboloma , Agregados Proteicos/efeitos dos fármacos , Escopoletina/farmacologia , alfa-Sinucleína/metabolismo , Produtos Biológicos/química , Produtos Biológicos/farmacologia , Linhagem Celular , Flavonóis/química , Fluorescência , Humanos , Interações Hidrofóbicas e Hidrofílicas , Isoflavonas/química , Cinética , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Conformação Proteica , Escopoletina/química , Tirosina/metabolismo , alfa-Sinucleína/química , alfa-Sinucleína/ultraestrutura
15.
Adv Exp Med Biol ; 1339: 221-226, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-35023109

RESUMO

Conducting cells of the heart and nerve cells of the brain are having the ability to generate and transmit electrical signals. Recording of neural signals became an important research issue for better analysis and better control of neurological functions by using implantable devices. In neural recording systems, the most critical part is the power constraint neural amplifier. The major challenges of neural front ends are low power dissipation and low input-referred noise. This work describes a low-noise amplifier that uses Metal Oxide Semiconductor bipolar pseudo-resistor elements to amplify signals from 0.03 millihertz to 8.4 kilohertz. This design is suitable for neurodegenerative disorders like Parkinson's disease and Alzheimer's. This topology reduces major noise in low-frequency circuits. By choosing input devices as PMOS transistors and also by properly sizing the devices, flicker noise is reduced. Noise and power trade-off is quantified by calculating noise efficiency factor (NEF) which is improved by using the proposed design. The circuit is implemented in 180 nm technology and is operated with a dual power supply range of ±2.5 V.


Assuntos
Doenças Neurodegenerativas , Amplificadores Eletrônicos , Encéfalo , Desenho de Equipamento , Humanos , Neurônios
16.
Biochimie ; 176: 181-191, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32717409

RESUMO

The ribosomal protein P2 of Plasmodium falciparum, (PfP2), performs certain unique extra-ribosomal functions. During the few hours of cell-division, PfP2 protein moves to the external surface of the infected erythrocytes (IE) as an SDS-resistant oligomer, and at that stage treatment with specific anti- PfP2 antibodies results in an arrest of the parasite cell-division. Amongst the oligomeric forms of PfP2, mainly the homo-tetramer is peripherally anchored on the external surface of the IE. To study the anchoring of PfP2 tetramer on IE-surface, we have explored the binding properties of PfP2 protein. Using NMR and erythrocyte pull-down studies, here we report that the homo-tetrameric PfP2 protein interacted specifically with erythrocytes and not leukocytes. The hydrophobic N-terminal 72 amino acid region is the major interacting domain. The binding of P2 to RBCs was neuraminidase resistant, but trypsin sensitive. The RBC binding was exclusive to the Plasmodium PfP2 protein as even the homologous protein of the closely related Apicomplexan parasite Toxoplasma gondii TgP2 protein did not interact with erythrocytes. Pull down assays, immunoprecipitation and mass spectrometry data showed that erythrocytic Band 3 protein is a possible interactor of Plasmodium PfP2 protein on the erythrocyte surface.


Assuntos
Eritrócitos/química , Plasmodium falciparum/química , Proteínas de Protozoários/química , Proteínas Ribossômicas/química , Eritrócitos/metabolismo , Humanos , Plasmodium falciparum/metabolismo , Proteínas de Protozoários/metabolismo , Proteínas Ribossômicas/metabolismo
17.
RSC Adv ; 10(36): 21174-21179, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-35518727

RESUMO

A new class of NOAH NMR experiments (NOAH-AST and NOAH-ASTPS), with the abbreviations, A: 1,1-ADEQUATE, S: sensitivity improved version of multiplicity-edited (ME)-HSQC, T: TOCSY, and TPS: pure shift TOCSY, are reported to obtain complete chemical shift assignments of small organic molecules from a single NMR experiment. While NOAH-AST provides 13C-13C, 1H-13C, and 1H-1H connectivities for molecules with well resolved chemical shifts, NOAH-ASTPS experiments discern 1H-1H connectivities even in complex organic molecules such as steroids at ultra-high resolution. These methods are very flexible and allow to record data through non-uniform-sampling, which reduces the experimental time to a great extent. In order to make these methods friendly to non-NMR experts (especially organic chemists and natural product scientists), python scripts have been developed and they help researchers in using these methods.

18.
Int J Biol Macromol ; 141: 585-595, 2019 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-31505208

RESUMO

Self-assembly of α-synuclein (α-Syn) is linked with a variety of neurodegenerative diseases collectively called as α-synucleiopathies. Therefore, discovering suitable inhibitors for this self-association process of α-Syn is a subject of intense research. In this background, we have demonstrated here that the natural compound, Safranal, delays/inhibits α-Syn fibrillation/aggregation, and we have also characterized its mode of action. The α-Syn fibrillation/aggregation kinetics studies in combination with TEM studies demonstrated that Safranal effectively inhibits α-Syn fibrillation/aggregation. NMR studies revealed that Safranal binds with α-Syn and stabilizes the monomeric protein. ANS fluorescence and CD measurements indicated that Safranal binds to the hydrophobic residues of the protein and causes delay in the formation of ß-sheet rich structures which are crucial for the fibrillation to occur. The results obtained from fluorescence quenching, NMR and ANS binding assays, when analysed taking into consideration the molecular structure of Safranal provide valuable insights into the mechanism of inhibition of α-Syn fibrillation/aggregation. We infer that inhibition of α-Syn fibrillation/aggregation is primarily driven by hydrophobic interactions between Safranal and the protein. Further, Safranal is also seen to dis-aggregates pre-formed α-Syn fibrils. These findings implicate that Safranal could become a potent therapeutic intervention in Parkinson's disease and other protein aggregation related disorders.


Assuntos
Cicloexenos/farmacologia , Agregados Proteicos/efeitos dos fármacos , Terpenos/farmacologia , alfa-Sinucleína/química , Cicloexenos/metabolismo , Relação Dose-Resposta a Droga , Interações Hidrofóbicas e Hidrofílicas , Estrutura Secundária de Proteína/efeitos dos fármacos , Solubilidade , Terpenos/metabolismo , alfa-Sinucleína/metabolismo
19.
J Phys Chem B ; 123(24): 5086-5098, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-31136713

RESUMO

Intrinsically disordered proteins (IDPs) form a special category because they lack a unique well-folded 3D structure under physiological conditions. They play crucial role in cell signaling and regulatory functions and are responsible for several diseases. Although they are abundant in nature, only a small fraction of them have been characterized until date. Such proteins adopt a range of conformations and can undergo transformation from disordered-to-ordered state or vice versa upon binding to ligand. Insights of such conformational transition is perplexing in several cases. In the present study, we characterized disordered as well as ordered states and the interactions contributing the transitions through a mutational study by employing replica exchange molecular dynamics simulation with generalized Born implicit solvent model on a protein from the ßγ-crystallin superfamily. Most of the proteins within this superfamily are inherently ordered and highly stable. However, Hahellin, although a member of the ßγ-crystallin family, is intrinsically disordered in its apo-form which takes a well-ordered ßγ-crystallin fold upon binding to Ca2+. It is intriguing that the mutation at the fifth position of the canonical motif to Arg increases the domain stability in several ordered microbial ßγ-crystallins with concomitant loss in Ca2+ binding affinity. We carried out similar Ser to Arg mutations at fifth position of the canonical motif for the first time in an intrinsically disordered protein to understand the mechanistic insights of conformational transition. Our study revealed that newly formed ionic and hydrogen bonding interactions at the canonical Ca2+ binding sites play a crucial role in transforming the disordered conformation into ordered ßγ-crystallin.


Assuntos
Cristalinas/química , Cristalinas/genética , Proteínas Intrinsicamente Desordenadas/química , Proteínas Intrinsicamente Desordenadas/genética , Simulação de Dinâmica Molecular , Mutação , Cálcio/química , Cálcio/metabolismo , Cristalinas/metabolismo , Ligação de Hidrogênio , Proteínas Intrinsicamente Desordenadas/metabolismo , Conformação Proteica
20.
Biomol NMR Assign ; 13(2): 267-273, 2019 10.
Artigo em Inglês | MEDLINE | ID: mdl-30937734

RESUMO

The centromeric chromatin plays an essential role in regulating the attachment of microtubules and controlling the segregation of sister chromatids during mitosis. In budding yeast, the evolutionary conserved histone variant, Cse4 is a vital component of the multiprotein kinetochore complex and is recruited to the centromere through its chaperone, Suppressor of chromosome mis-segregation (Scm3). Scm3 is an inner kinetochore protein crucial for the formation of a functional inner kinetochore. Scm3 has been known to play an active role in the assembly of the centromeric nucleosome and its deletion has been found to have deleterious effects on the cells leading to chromosome segregation defects. However, structural details of monomeric full length Scm3 have remained elusive so far. Here, we report the backbone and side-chain resonance assignments of centromeric protein, Scm3. 1H, 13C and 15N chemical shifts of Scm3 have been obtained by various 2D and 3D heteronuclear NMR experiments at pH 7.4 and 283 K.


Assuntos
Proteínas Cromossômicas não Histona/química , Ressonância Magnética Nuclear Biomolecular , Proteínas de Saccharomyces cerevisiae/química
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