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1.
Nucleic Acids Res ; 51(15): 7900-7913, 2023 08 25.
Artigo em Inglês | MEDLINE | ID: mdl-37462073

RESUMO

PHO84 is a budding yeast gene reported to be negatively regulated by its cognate antisense transcripts both in cis and in trans. In this study, we performed Transient-transcriptome sequencing (TT-seq) to investigate the correlation of sense/antisense pairs in a dbp2Δ strain and found over 700 sense/antisense pairs, including PHO84, to be positively correlated, contrasting the prevailing model. To define what mechanism regulates the PHO84 gene and how this regulation could have been originally attributed to repression by the antisense transcript, we conducted a series of molecular biology and genetics experiments. We now report that the 3' untranslated region (3'UTR) of PHO84 plays a repressive role in sense expression, an activity not linked to the antisense transcripts. Moreover, we provide results of a genetic screen for 3'UTR-dependent repression of PHO84 and show that the vast majority of identified factors are linked to negative regulation. Finally, we show that the PHO84 promoter and terminator form gene loops which correlate with transcriptional repression, and that the RNA-binding protein, Tho1, increases this looping and the 3'UTR-dependent repression. Our results negate the current model for antisense non-coding transcripts of PHO84 and suggest that many of these transcripts are byproducts of open chromatin.


Assuntos
RNA Antissenso , Saccharomyces cerevisiae , Regiões 3' não Traduzidas/genética , Cromatina , Genômica , RNA Antissenso/genética , RNA Antissenso/metabolismo , Saccharomyces cerevisiae/metabolismo , Regulação Fúngica da Expressão Gênica
2.
Chemistry ; : e202401562, 2024 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-39140457

RESUMO

Noninvasive control over the reversible generation of singlet oxygen (1O2) has found the enormous practical implications in the field of biomedical science. However, metal-free pure organic emitters, connected with a photoswitch, capable of generating "on-demand" 1O2 via triplet harvesting remain exceedingly rare; therefore, the utilization of these organic materials for the reversible control of singlet oxygen production remains at its infancy. Herein, an ambient triplet mediated emission in quinoline-dithienylethene (DTE)-core-substituted naphthalene diimide (cNDI) derivative is unveiled via delayed fluorescence. The quinoline-DTE-cNDI triad displayed enhanced photoswitching efficiency via double FRET mechanism.  It was found to have direct utilization in controlled photosensitized organic transformations via efficient generation of singlet oxygen (yield ΦΔ ~ 0.73). The designed molecule exhibits a long-lived emission (τ ∼ 1.1 µs) and very small singlet-triplet splitting (ΔSET) of 0.13 eV empowering it to display delayed fluorescence. Comprehensive steady state and time-resolved emission spectroscopy (TRES) analyses along with DFT calculations offer detailed understandings into the excited-state manifolds of organic compound and energy transfer (ET) pathways involved in 1O2 generation.

3.
Langmuir ; 39(21): 7307-7316, 2023 05 30.
Artigo em Inglês | MEDLINE | ID: mdl-37192174

RESUMO

A histidine-based amphiphilic peptide (P) has been found to form an injectable transparent hydrogel in phosphate buffer solution over a pH range from 7.0 to 8.5 with an inherent antibacterial property. It also formed a hydrogel in water at pH = 6.7. The peptide self-assembles into a nanofibrillar network structure which is characterized by high-resolution transmission electron microscopy, field-emission scanning electron microscopy, atomic force microscopy, small-angle X-ray scattering, Fourier-transform infrared spectroscopy, and wide-angle powder X-ray diffraction. The hydrogel exhibits efficient antibacterial activity against both Gram-positive bacteria Staphylococcus aureus (S. aureus) and Gram-negative bacteria Escherichia coli (E. coli). The minimum inhibitory concentration of the hydrogel ranges from 20 to 100 µg/mL. The hydrogel is capable of encapsulation of the drugs naproxen (a non-steroidal anti-inflammatory drug), amoxicillin (an antibiotic), and doxorubicin, (an anticancer drug), but, selectively and sustainably, the gel releases naproxen, 84% being released in 84 h and amoxicillin was released more or less in same manner with that of the naproxen. The hydrogel is biocompatible with HEK 293T cells as well as NIH (mouse fibroblast cell line) cells and thus has potential as a potent antibacterial and drug releasing agent. Another remarkable feature of this hydrogel is its magnification property like a convex lens.


Assuntos
Histidina , Staphylococcus aureus , Animais , Camundongos , Amoxicilina , Antibacterianos/química , Antibacterianos/farmacologia , Liberação Controlada de Fármacos , Escherichia coli , Hidrogéis/farmacologia , Hidrogéis/química , Naproxeno , Peptídeos
4.
Immunol Invest ; 52(8): 1065-1095, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37812224

RESUMO

Colorectal cancer (CRC) is the third most prevalent malignancy with increased incidence and mortality rates worldwide. Traditional treatment approaches have attempted to efficiently target CRC; however, they have failed in most cases, owing to the cytotoxicity and non-specificity of these therapies. Therefore, it is essential to develop an effective alternative therapy to improve the clinical outcomes in heterogeneous CRC cases. Immunotherapy has transformed cancer treatment with remarkable efficacy and overcomes the limitations of traditional treatments. With an understanding of the cancer-immunity cycle and tumor microenvironment evolution, current immunotherapy approaches have elicited enhanced antitumor immune responses. In this comprehensive review, we outline the latest advances in immunotherapy targeting CRC and provide insights into antitumor immune responses reported in landmark clinical studies. We focused on highlighting the combination approaches that synergistically induce immune responses and eliminate immunosuppression. This review aimed to understand the limitations and potential of recent immunotherapy clinical studies conducted in the last five years (2019-2023) and to transform this knowledge into a rational design of clinical trials intended for effective antitumor immune responses in CRC.


Assuntos
Neoplasias Colorretais , Humanos , Neoplasias Colorretais/terapia , Imunoterapia , Terapia de Imunossupressão , Microambiente Tumoral
5.
J Trop Pediatr ; 68(2)2022 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-35220426

RESUMO

The neonatal skin microbiome consists of all the genomes and genetic products of microorganisms harboring on an infant's skin. Host and the microbiota develop a harmonious environment resulting in symbiosis. Any disruption of this environment could lead to pathological disease. This study was conducted to understand the neonatal skin microbiome of very preterm neonates (under 32 weeks) admitted to the Neonatal Intensive Care Unit(NICU) at a tertiary healthcare setting before and after kangaroo mother care (KMC), using next-generation sequencing (NGS). Skin swabs were collected on two different occasions and analyzed using the NGS technique after amplification via polymerase chain reaction. The results showed relative abundance for Mycobacterium tuberculosis in 83.33% and 66.67% (p = 0.29) and Mycobacteroides abscessus in 100% and 93.33% (p = 0.30) of the very preterm neonates on the skin microbiome before and after KMC, respectively as an incidental finding. The mere presence of these bacilli as commensals or as potential pathogens is alarming due to the risk of early exposure and incidence of tuberculosis from birth. These findings, in our view, are the first findings to be established in such a setting.


Assuntos
Método Canguru , Microbiota , Mycobacterium , Criança , Humanos , Lactente Extremamente Prematuro , Recém-Nascido , Unidades de Terapia Intensiva Neonatal
6.
J Biol Chem ; 293(34): 12975-12991, 2018 08 24.
Artigo em Inglês | MEDLINE | ID: mdl-29959225

RESUMO

Parkinson's disease is mainly a sporadic disorder in which both environmental and cellular factors play a major role in the initiation of this disease. Glycosaminoglycans (GAG) are integral components of the extracellular matrix and are known to influence amyloid aggregation of several proteins, including α-synuclein (α-Syn). However, the mechanism by which different GAGs and related biological polymers influence protein aggregation and the structure and intercellular spread of these aggregates remains elusive. In this study, we used three different GAGs and related charged polymers to establish their role in α-Syn aggregation and associated biological activities of these aggregates. Heparin, a representative GAG, affected α-Syn aggregation in a concentration-dependent manner, whereas biphasic α-Syn aggregation kinetics was observed in the presence of chondroitin sulfate B. Of note, as indicated by 2D NMR analysis, different GAGs uniquely modulated α-Syn aggregation because of the diversity of their interactions with soluble α-Syn. Moreover, subtle differences in the GAG backbone structure and charge density significantly altered the properties of the resulting amyloid fibrils. Each GAG/polymer facilitated the formation of morphologically and structurally distinct α-Syn amyloids, which not only displayed variable levels of cytotoxicity but also exhibited an altered ability to internalize into cells. Our study supports the role of GAGs as key modulators in α-Syn amyloid formation, and their distinct activities may regulate amyloidogenesis depending on the type of GAG being up- or down-regulated in vivo.


Assuntos
Amiloide/química , Regulação da Expressão Gênica/efeitos dos fármacos , Glicosaminoglicanos/farmacologia , Polímeros/química , Agregados Proteicos/efeitos dos fármacos , alfa-Sinucleína/química , Proliferação de Células , Humanos , Neuroblastoma/metabolismo , Neuroblastoma/patologia , Células Tumorais Cultivadas , alfa-Sinucleína/genética , alfa-Sinucleína/metabolismo
7.
Mol Plant Microbe Interact ; 32(8): 1047-1060, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30794480

RESUMO

Phytophthora ramorum is a destructive pathogen that causes sudden oak death disease. The genome sequence of P. ramorum isolate Pr102 was previously produced, using Sanger reads, and contained 12 Mb of gaps. However, isolate Pr102 had shown reduced aggressiveness and genome abnormalities. In order to produce an improved genome assembly for P. ramorum, we performed long-read sequencing of highly aggressive P. ramorum isolate CDFA1418886 (abbreviated as ND886). We generated a 60.5-Mb assembly of the ND886 genome using the Pacific Biosciences (PacBio) sequencing platform. The assembly includes 302 primary contigs (60.2 Mb) and nine unplaced contigs (265 kb). Additionally, we found a 'highly repetitive' component from the PacBio unassembled unmapped reads containing tandem repeats that are not part of the 60.5-Mb genome. The overall repeat content in the primary assembly was much higher than the Pr102 Sanger version (48 versus 29%), indicating that the long reads have captured repetitive regions effectively. The 302 primary contigs were phased into 345 haplotype blocks and 222,892 phased variants, of which the longest phased block was 1,513,201 bp with 7,265 phased variants. The improved phased assembly facilitated identification of 21 and 25 Crinkler effectors and 393 and 394 RXLR effector genes from two haplotypes. Of these, 24 and 25 RXLR effectors were newly predicted from haplotypes A and B, respectively. In addition, seven new paralogs of effector Avh207 were found in contig 54, not reported earlier. Comparison of the ND886 assembly with Pr102 V1 assembly suggests that several repeat-rich smaller scaffolds within the Pr102 V1 assembly were possibly misassembled; these regions are fully encompassed now in ND886 contigs. Our analysis further reveals that Pr102 is a heterokaryon with multiple nuclear types in the sequences corresponding to contig 10 of ND886 assembly.


Assuntos
Variações do Número de Cópias de DNA , Genoma de Protozoário , Phytophthora , Polimorfismo Genético , Genoma de Protozoário/genética , Haplótipos , Phytophthora/genética
8.
J Basic Microbiol ; 59(10): 1016-1030, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31430397

RESUMO

Heavy metals such as lead, chromium, and metalloid like arsenic dominate the pinnacle in posing a threat to life. Being environment-friendly, elucidating the mechanism by which microorganisms detoxify such elements has always been an active field of research hitherto. In the present study, we have investigated the capability of nitrogen-deprived Papiliotrema laurentii strain RY1 toward enhanced tolerance and neutralizing toxic elements. There were biosorption and bioprecipitation of lead and chromium at the cell surfaces. Bioprecipitation mechanisms included the formation of lead phosphates and pyromorphites from lead, grimaldite from chromium. Transcripts such as metallothionein, aquaporins, and arsenical pump-driving ATPase have been surmised to be involved in the detoxification of elements. Furthermore, activation of antioxidant defense mechanisms for the cells for each of the elements should contribute towards yeast's propagation. The efficiency of removal of elements for live cells and immobilized cells were high for lead and chromium. To the best of our knowledge, this is the first report of such high tolerance of lead, arsenic, and chromium for any yeast. The yeast showed such varied response under dual stress due to nitrogen starvation and in the presence of respective elements. The yeast possesses promising potentials in nitrogen deprived and enriched environments to aid in bioremediation sectors.


Assuntos
Arsênio/metabolismo , Basidiomycota/metabolismo , Poluentes Ambientais/metabolismo , Metais Pesados/metabolismo , Nitrogênio/metabolismo , Antioxidantes/metabolismo , Arsênio/toxicidade , Basidiomycota/efeitos dos fármacos , Basidiomycota/crescimento & desenvolvimento , Biodegradação Ambiental , Transporte Biológico/genética , Cádmio/metabolismo , Cádmio/toxicidade , Poluentes Ambientais/toxicidade , Expressão Gênica , Inativação Metabólica , Chumbo/metabolismo , Chumbo/toxicidade , Metalotioneína/genética , Metais Pesados/toxicidade , Testes de Sensibilidade Microbiana
9.
Biochemistry ; 57(33): 5014-5028, 2018 08 21.
Artigo em Inglês | MEDLINE | ID: mdl-30025458

RESUMO

Amyloid formation of α-synuclein (α-Syn) and its familial mutations are directly linked with Parkinson's disease (PD) pathogenesis. Recently, a new familial α-Syn mutation (A53E) was discovered, associated with an early onset aggressive form of PD, which delays α-Syn aggregation. When we overexpressed wild-type (WT) and A53E proteins in cells, showed neither toxicity nor aggregate formation, suggesting merely overexpression may not recapitulate the PD phenotype in cell models. We hypothesized that cells expressing the A53E mutant might possess enhanced susceptibility to PD-associated toxicants compared to that of the WT. When cells were treated with PD toxicants (dopamine and rotenone), cells expressing A53E showed more susceptibility to cell death along with compromised mitochondrial potential and an increased production of reactive oxygen species. The higher toxicity of A53E could be due to more oligomers being formed in cells as confirmed by a dot blot assay using amyloid specific OC and A11 antibody and using an  in vitro aggregation study. The cellular model presented here suggests that along with familial mutation, environmental and other cellular factors might play a crucial role in dictating PD pathogenesis.


Assuntos
Apoptose/efeitos dos fármacos , Dopamina/toxicidade , Agregados Proteicos/genética , Rotenona/toxicidade , alfa-Sinucleína/metabolismo , Linhagem Celular Tumoral , Humanos , Cinética , Potencial da Membrana Mitocondrial , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/fisiologia , Mutação , Agregação Patológica de Proteínas/metabolismo , Multimerização Proteica , Espécies Reativas de Oxigênio/metabolismo , alfa-Sinucleína/genética
10.
Biochemistry ; 57(35): 5183-5187, 2018 09 04.
Artigo em Inglês | MEDLINE | ID: mdl-29771508

RESUMO

The involvement of α-synuclein (α-Syn) amyloid formation in Parkinson's disease (PD) pathogenesis is supported by the discovery of α-Syn gene (SNCA) mutations linked with familial PD, which are known to modulate the oligomerization and aggregation of α-Syn. Recently, the A53V mutation has been discovered, which leads to late-onset PD. In this study, we characterized for the first time the biophysical properties of A53V, including the aggregation propensities, toxicity of aggregated species, and membrane binding capability, along with those of all familial mutations at the A53 position. Our data suggest that the A53V mutation accelerates fibrillation of α-Syn without affecting the overall morphology or cytotoxicity of fibrils compared to those of the wild-type (WT) protein. The aggregation propensity for A53 mutants is found to decrease in the following order: A53T > A53V > WT > A53E. In addition, a time course aggregation study reveals that the A53V mutant promotes early oligomerization similar to the case for the A53T mutation. It promotes the largest amount of oligomer formation immediately after dissolution, which is cytotoxic. Although in the presence of membrane-mimicking environments, the A53V mutation showed an extent of helix induction capacity similar to that of the WT protein, it exhibited less binding to lipid vesicles. The nuclear magnetic resonance study revealed unique chemical shift perturbations caused by the A53V mutation compared to those caused by other mutations at the A53 site. This study might help to establish the disease-causing mechanism of A53V in PD pathology.


Assuntos
Amiloide/química , Membrana Celular/metabolismo , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Mutação , Agregados Proteicos , alfa-Sinucleína/química , alfa-Sinucleína/metabolismo , Humanos , Cinética , Proteínas Mutantes/genética , alfa-Sinucleína/genética
11.
Biomacromolecules ; 19(6): 1826-1839, 2018 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-29701992

RESUMO

Extracellular matrices (ECM) play an enormous role in any living system, controlling various factors and eventually fates of cells. ECM regulates cell fate by providing constant exogenous signals altering intracellular signal transduction for diverse pathways including proliferation, migration, differentiation, and apoptosis. Biomaterial scaffolds are designed to mimic the natural extracellular matrix such that the cells could recapitulate natural events alike their natural niche. Therefore, the success of tissue engineering is largely dependent on how one can engineer the natural matrix properties at nanoscale precision. In this aspect, several recent studies have suggested that, as long as amyloid fibrils are not toxic, they can be utilized for cell adhesion and tissue engineering applications due to its ECM mimetic surface topography and ability to mediate active cell adhesion via focal adhesions. Although historically associated with human diseases, amyloids have presently emerged as one of the excellent biomaterials evolved in nature. In this review, we focus on the recent advances of amyloid-based biomaterials for cell adhesion and tissue engineering applications.


Assuntos
Amiloide/química , Materiais Biocompatíveis/química , Adesão Celular/fisiologia , Engenharia Tecidual/métodos , Amiloide/metabolismo , Animais , Encéfalo/citologia , Diferenciação Celular/efeitos dos fármacos , Matriz Extracelular/química , Humanos , Hidrogéis/administração & dosagem , Hidrogéis/química , Peptídeos e Proteínas de Sinalização Intercelular/farmacocinética , Transplante de Células-Tronco/métodos , Células-Tronco/citologia , Células-Tronco/efeitos dos fármacos , Engenharia Tecidual/instrumentação
12.
Adv Exp Med Biol ; 1112: 79-97, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30637692

RESUMO

Amyloids are highly ordered peptide/protein aggregates traditionally associated with multiple human diseases including neurodegenerative disorders. However, recent studies suggest that amyloids can also perform several biological functions in organisms varying from bacteria to mammals. In many lower organisms, amyloid fibrils function as adhesives due to their unique surface topography. Recently, amyloid fibrils have been shown to support attachment and spreading of mammalian cells by interacting with the cell membrane and by cell adhesion machinery activation. Moreover, similar to cellular responses on natural extracellular matrices (ECMs), mammalian cells on amyloid surfaces also use integrin machinery for spreading, migration, and differentiation. This has led to the development of biocompatible and implantable amyloid-based hydrogels that could induce lineage-specific differentiation of stem cells. In this chapter, based on adhesion of both lower organisms and mammalian cells on amyloid nanofibrils, we posit that amyloids could have functioned as a primitive extracellular matrix in primordial earth.


Assuntos
Amiloide/fisiologia , Adesão Celular , Animais , Diferenciação Celular , Matriz Extracelular , Humanos , Integrinas
13.
Ecotoxicol Environ Saf ; 148: 620-631, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29128823

RESUMO

Copper oxide nanoparticles and copper sulfate are established contaminants of water and soil. Metaphire posthuma is a common variety of earthworm distributed in moist soil of Indian subcontinent. Comparative toxicity of copper nanoparticles and copper sulfate were investigated with reference to selected immune associated parameters of earthworm. Total count, phagocytic response, generation of cytotoxic molecules (superoxide anion, nitric oxide), activities of enzymes like phenoloxidase, superoxide dismutase, catalase, acid phosphatase, alkaline phosphatase and total protein of coelomocytes were estimated under the exposures of 100, 500, 1000mg of copper oxide nanoparticles and copper sulfate per kg of soil for 7 and 14 d. A significant decrease in the total coelomocyte count were recorded with maximum depletion as 15.45 ± 2.2 and 12.5 ± 2 × 104 cells/ml under the treatment of 1000mg/kg of copper nanoparticles and copper sulfate for 14 d respectively. A significant decrease in generation of nitric oxide and activity of phenoloxidase were recorded upon exposure of both toxins for 7 and 14 d indicating possible decline in cytotoxic status of the organism. A maximum inhibition of superoxide dismutase activity was recorded as 0.083 ± 0.0039 and 0.055 ± 0.0057 unit/mg protein/minute against 1000mg/kg of copper nanoparticles and copper sulfate treatment for 14 d respectively. Activities of catalase and alkaline phosphatase were inhibited by all experimental concentrations of both toxins in the coelomocytes of earthworm. These toxins were recorded to be modifiers of the major immune associated parameters of M. posthuma. Unrestricted contamination of soil by sulfate and oxide nanoparticles of copper may lead to an undesirable shift in the innate immunological status of earthworm leading to a condition of immune compromisation and shrinkage in population density of this species in its natural habitat. This article is the first time report of immunological toxicity of nanoparticles and sulfate salt of copper in M.posthuma inhabiting the soil of India, an agriculture based country.


Assuntos
Sulfato de Cobre/toxicidade , Cobre/toxicidade , Nanopartículas/toxicidade , Oligoquetos/fisiologia , Poluentes do Solo/toxicidade , Agricultura , Animais , Ecossistema , Poluição Ambiental , Índia , Monofenol Mono-Oxigenase/metabolismo , Óxido Nítrico/metabolismo , Solo/química , Superóxidos/metabolismo
14.
Angew Chem Int Ed Engl ; 57(19): 5262-5266, 2018 05 04.
Artigo em Inglês | MEDLINE | ID: mdl-29524323

RESUMO

α-Synuclein (α-Syn) aggregation is associated with Parkinson's disease (PD) pathogenesis. In PD, the role of oligomers versus fibrils in neuronal cell death is debatable, but recent studies suggest oligomers are a proximate neurotoxin. Herein, we show that soluble α-Syn monomers undergo a transformation from a solution to a gel state on incubation at high concentration. Detailed characterization of the gel showed the coexistence of monomers, oligomers, and short fibrils. In vitro, the gel was highly cytotoxic to human neuroblastoma cells. The individual constituents of the gel are short-lived species but toxic to the cells. They comprise a structurally heterogeneous population of α-helical and ß-sheet-rich oligomers and short fibrils with the cross-ß motif. Given the recent evidence of the gel-like state of the protein associated with neurodegenerative diseases, the gel state of α-Syn in this study represents a mechanistic and structural model for the in vivo toxicity of α-Syn in PD.


Assuntos
Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , alfa-Sinucleína/metabolismo , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Géis , Humanos , Doença de Parkinson/tratamento farmacológico , Tamanho da Partícula , Agregados Proteicos/efeitos dos fármacos , Propriedades de Superfície , alfa-Sinucleína/antagonistas & inibidores
15.
Biochim Biophys Acta Gen Subj ; 1861(2): 365-374, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27916677

RESUMO

BACKGROUND: Copper is an essential trace element required for the proper functioning of various enzymes present in the central nervous system. An imbalance in the copper homeostasis results in the pathology of various neurodegenerative disorders including Parkinson's Disease. Hence, residue specific interaction of Cu2+ to α-Syn along with the familial mutants H50Q and G51D needs to be studied in detail. METHODS: We investigated the residue specific mapping of Cu2+ binding sites and binding strength using solution-state NMR and ITC respectively. The aggregation kinetics, secondary structural changes, and morphology of the formed fibrils in the presence and absence of Cu2+ were studied using fluorescence, CD, and AFM respectively. RESULTS: Copper binding to α-Syn takes place at three different sites with a higher affinity for the region 48-53. While one of the sites got abolished in the case of H50Q, the mutant G51D showed a binding pattern similar to WT. The aggregation kinetics of these proteins in the presence of Cu2+ showed an enhanced rate of fibril formation with a pronounced effect for G51D. CONCLUSION: Cu2+ binding results in the destabilization of long-range tertiary interactions in α-Syn leading to the exposure of highly amyloidogenic NAC region which results in the increased rate of fibril formation. Although the residues 48-53 have a stronger affinity for Cu2+ in case of WT and G51D, the binding is not responsible for enhancing the rate of fibril formation in case of H50Q. GENERAL SIGNIFICANCE: These findings will help in the better understanding of Cu2+ catalyzed aggregation of synucleins.


Assuntos
Amiloide/metabolismo , Proteínas Amiloidogênicas/metabolismo , Cobre/metabolismo , alfa-Sinucleína/metabolismo , Amiloidose/metabolismo , Amiloidose/patologia , Sítios de Ligação , Linhagem Celular , Humanos , Cinética , Doença de Parkinson/metabolismo , Doença de Parkinson/patologia , Agregação Patológica de Proteínas/metabolismo , Agregação Patológica de Proteínas/patologia
16.
J Basic Microbiol ; 57(10): 862-872, 2017 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-28745822

RESUMO

The master regulator, DnrI of Streptomyces peucetius is a member of the family of transcriptional activator, Streptomyces antibiotic regulatory proteins (SARP), which controls the biosynthesis of antitumor anthracycline, daunorubicin (DNR) and doxorubicin (DXR). The binding of DnrI to the heptameric repeat sequence found within the -35 promoter region of biosynthetic gene, dpsE activates it. To combat the increased level of intracellular DNR, the cell has developed self resistance mechanism mediated by drrAB and drrC genes which are regulated by regulatory genes. We find that a drug non-producing mutant, ΔdpsA, showed sensitive phenotype in plate assay along with an increased level of dnrI transcript. Whereas the mutant grown in the presence of DNR showed a resistant phenotype with a six and eight folds increase in drrAB and drrC transcripts respectively. Computational studies followed by molecular docking showed that DnrI bound as a monomer to a slightly modified heptameric DNA motif, 5'-ACACGCA in drrA and 5'-ACAACCT in drrC which was also proved by electrophoretic mobility shift assay. These findings confirm that DnrI belongs to winged helix-turn-helix DNA-binding protein with Tetratricopeptide Repeat domain. The transcriptional regulator DnrI binds to the resistance genes at specific sites but they are activated only when an increased load of intracellular DNR is sensed.


Assuntos
Transportadores de Cassetes de Ligação de ATP/metabolismo , Proteínas de Bactérias/metabolismo , DNA Bacteriano/genética , Daunorrubicina/metabolismo , Streptomyces/metabolismo , Fatores de Transcrição/metabolismo , Transportadores de Cassetes de Ligação de ATP/genética , Proteínas de Bactérias/genética , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Daunorrubicina/biossíntese , Daunorrubicina/farmacologia , Regulação Bacteriana da Expressão Gênica , Genes Bacterianos , Genes MDR , Simulação de Acoplamento Molecular , Proteínas Associadas à Resistência a Múltiplos Medicamentos , Mutação , Streptomyces/genética , Streptomyces/crescimento & desenvolvimento , Fatores de Transcrição/genética , Ativação Transcricional
17.
J Biol Chem ; 289(24): 16884-903, 2014 Jun 13.
Artigo em Inglês | MEDLINE | ID: mdl-24782311

RESUMO

The storage of protein/peptide hormones within subcellular compartments and subsequent release are crucial for their native function, and hence these processes are intricately regulated in mammalian systems. Several peptide hormones were recently suggested to be stored as amyloids within endocrine secretory granules. This leads to an apparent paradox where storage requires formation of aggregates, and their function requires a supply of non-aggregated peptides on demand. The precise mechanism behind amyloid formation by these hormones and their subsequent release remain an open question. To address this, we examined aggregation and fibril reversibility of a cyclic peptide hormone somatostatin (SST)-14 using various techniques. After proving that SST gets stored as amyloid in vivo, we investigated the role of native structure in modulating its conformational dynamics and self-association by disrupting the disulfide bridge (Cys(3)-Cys(14)) in SST. Using two-dimensional NMR, we resolved the initial structure of somatostatin-14 leading to aggregation and further probed its conformational dynamics in silico. The perturbation in native structure (S-S cleavage) led to a significant increase in conformational flexibility and resulted in rapid amyloid formation. The fibrils formed by disulfide-reduced noncyclic SST possess greater resistance to denaturing conditions with decreased monomer releasing potency. MD simulations reveal marked differences in the intermolecular interactions in SST and noncyclic SST providing plausible explanation for differential aggregation and fibril reversibility observed experimentally in these structural variants. Our findings thus emphasize that subtle changes in the native structure of peptide hormone(s) could alter its conformational dynamics and amyloid formation, which might have significant implications on their reversible storage and secretion.


Assuntos
Amiloide/química , Dissulfetos/química , Exocitose , Somatostatina/química , Sequência de Aminoácidos , Amiloide/metabolismo , Animais , Hipotálamo/metabolismo , Simulação de Dinâmica Molecular , Dados de Sequência Molecular , Polimerização , Conformação Proteica , Ratos , Vesículas Secretórias/metabolismo , Somatostatina/metabolismo
18.
Langmuir ; 30(13): 3775-86, 2014 Apr 08.
Artigo em Inglês | MEDLINE | ID: mdl-24678792

RESUMO

It has been suggested that conjugated charged polymers are amyloid imaging agents and promising therapeutic candidates for neurological disorders. However, very less is known about their efficacy in modulating the amyloid aggregation pathway. Here, we studied the modulation of Parkinson's disease associated α-synuclein (AS) amyloid assembly kinetics using conjugated polyfluorene polymers (PF, cationic; PFS, anionic). We also explored the complexation of these charged polymers with the various AS aggregated species including amyloid fibrils and oligomers using multidisciplinary biophysical techniques. Our data suggests that both polymers irrespective of their different charges in the side chains increase the fibrilization kinetics of AS and also remarkably change the morphology of the resultant amyloid fibrils. Both polymers were incorporated/aligned onto the AS amyloid fibrils as evident from electron microscopy (EM) and atomic force microscopy (AFM), and the resultant complexes were structurally distinct from their pristine form of both polymers and AS supported by FTIR study. Additionally, we observed that the mechanism of interactions between the polymers with different species of AS aggregates were markedly different.


Assuntos
Amiloide/química , Polímeros de Fluorcarboneto/química , Agregados Proteicos , alfa-Sinucleína/química , Sequência de Aminoácidos , Benzotiazóis , Escherichia coli/genética , Escherichia coli/metabolismo , Polímeros de Fluorcarboneto/síntese química , Expressão Gênica , Humanos , Cinética , Microscopia de Força Atômica , Dados de Sequência Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Soluções , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Tiazóis , alfa-Sinucleína/genética
19.
Front Fungal Biol ; 5: 1355999, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38434188

RESUMO

Climate changes cause altering rainfall patterns resulting in an increase in drought occurrences globally. These events are disrupting plants and agricultural productivity. To evade droughts, plants try to adapt and modify in the best capacities possible. The plants have adapted by structurally modifying roots, stems, and leaves, as well as modifying functions. Lately, the association of microbial communities with plants has also been proven to be an important factor in aiding resilience. The fungal representatives of the microbial community also help safeguard the plants against drought. We discuss how these fungi associate with plants and contribute to evading drought stress. We specifically focus on Arbuscular mycorrhizal fungi (AMF) mediated mechanisms involving antioxidant defenses, phytohormone mediations, osmotic adjustments, proline expressions, fungal water absorption and transport, morphological modifications, and photosynthesis. We believe understanding the mechanisms would help us to optimize the use of fungi in agricultural practices. That way we could better prepare the plants for the anticipated future drought events.

20.
Wiley Interdiscip Rev RNA ; 15(4): e1864, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-39087253

RESUMO

A considerable proportion of the eukaryotic genome undergoes transcription, leading to the generation of noncoding RNA molecules that lack protein-coding information and are not subjected to translation. These noncoding RNAs (ncRNAs) are well recognized to have essential roles in several biological processes. Long noncoding RNAs (lncRNAs) represent the most extensive category of ncRNAs found in the human genome. Much research has focused on investigating the roles of cis-acting lncRNAs in the regulation of specific target gene expression. In the majority of instances, the regulation of sense gene expression by its corresponding antisense pair occurs in a negative (discordant) manner, resulting in the suppression of the target genes. The notion that a negative correlation exists between sense and antisense pairings is, however, not universally valid. In fact, several recent studies have reported a positive relationship between corresponding cis antisense pairs within plants, budding yeast, and mammalian cancer cells. The positive (concordant) correlation between anti-sense and sense transcripts leads to an increase in the level of the sense transcript within the same genomic loci. In addition, mechanisms such as altering chromatin structure, the formation of R loops, and the recruitment of transcription factors can either enhance transcription or stabilize sense transcripts through their antisense pairs. The primary objective of this work is to provide a comprehensive understanding of both aspects of antisense regulation, specifically focusing on the positive correlation between sense and antisense transcripts in the context of eukaryotic gene expression, including its implications towards cancer progression. This article is categorized under: RNA Processing > 3' End Processing Regulatory RNAs/RNAi/Riboswitches > Regulatory RNAs.


Assuntos
Regulação da Expressão Gênica , Humanos , Animais , RNA Antissenso/genética , RNA Antissenso/metabolismo , RNA Longo não Codificante/genética , RNA Longo não Codificante/metabolismo
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