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1.
Sci Rep ; 14(1): 8585, 2024 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-38615123

RESUMO

This paper provides an extensive examination of a sizable dataset of English tweets focusing on nine widely recognized cryptocurrencies, specifically Cardano, Binance, Bitcoin, Dogecoin, Ethereum, Fantom, Matic, Shiba, and Ripple. Our goal was to conduct a psycholinguistic and emotional analysis of social media content associated with these cryptocurrencies. Such analysis can enable researchers and experts dealing with cryptocurrencies to make more informed decisions. Our work involved comparing linguistic characteristics across the diverse digital coins, shedding light on the distinctive linguistic patterns emerging in each coin's community. To achieve this, we utilized advanced text analysis techniques. Additionally, this work unveiled an understanding of the interplay between these digital assets. By examining which coin pairs are mentioned together most frequently in the dataset, we established co-mentions among different cryptocurrencies. To ensure the reliability of our findings, we initially gathered a total of 832,559 tweets from X. These tweets underwent a rigorous preprocessing stage, resulting in a refined dataset of 115,899 tweets that were used for our analysis. Overall, our research offers valuable perception into the linguistic nuances of various digital coins' online communities and provides a deeper understanding of their interactions in the cryptocurrency space.

2.
Micromachines (Basel) ; 14(8)2023 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-37630183

RESUMO

Photothermal therapy is one of the most promising and rapidly developing fields in modern oncology due to its high efficiency, localized action, and minimal invasiveness. Polymeric nanoparticles (NPs) incorporating low molecular-weight photothermal dyes are capable of delivering therapeutic agents to the tumor site, releasing them in a controlled manner, and providing tumor treatment under external light irradiation. The nanoparticle synthesis components are critically important factors that influence the therapeutically significant characteristics of polymeric NPs. Here, we show the impact of stabilizers and solvents used for synthesis on the properties of PLGA NPs for photothermal therapy. We synthesized PLGA nanocarriers using the microemulsion method and varied the nature of the solvent and the concentration of the stabilizer-namely, chitosan oligosaccharide lactate. A phthalocyanine-based photosensitizer, which absorbs light in the NIR window, was encapsulated in the PLGA NPs. When mQ water was used as a solvent and chitosan oligosaccharide lactate was used at a concentration of 1 g/L, the PLGA NPs exhibited highly promising photothermal properties. The final composite of the nanocarriers demonstrated photoinduced cytotoxicity against EMT6/P cells under NIR laser irradiation in vitro and was suitable for bioimaging.

3.
Science ; 381(6655): 313-319, 2023 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-37384673

RESUMO

Loss of H2A-H2B histone dimers is a hallmark of actively transcribed genes, but how the cellular machinery functions in the context of noncanonical nucleosomal particles remains largely elusive. In this work, we report the structural mechanism for adenosine 5'-triphosphate-dependent chromatin remodeling of hexasomes by the INO80 complex. We show how INO80 recognizes noncanonical DNA and histone features of hexasomes that emerge from the loss of H2A-H2B. A large structural rearrangement switches the catalytic core of INO80 into a distinct, spin-rotated mode of remodeling while its nuclear actin module remains tethered to long stretches of unwrapped linker DNA. Direct sensing of an exposed H3-H4 histone interface activates INO80, independently of the H2A-H2B acidic patch. Our findings reveal how the loss of H2A-H2B grants remodelers access to a different, yet unexplored layer of energy-driven chromatin regulation.


Assuntos
Chaetomium , Montagem e Desmontagem da Cromatina , Cromatina , Histonas , Nucleossomos , Cromatina/química , DNA/química , Histonas/química , Nucleossomos/química , Microscopia Crioeletrônica , Chaetomium/química , Chaetomium/ultraestrutura
4.
Pharmaceutics ; 15(1)2023 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-36678860

RESUMO

Targeted nanoparticles of different origins are considered as new-generation diagnostic and therapeutic tools. However, there are no targeted drug formulations within the composition of nanoparticles approved by the FDA for use in the clinic, which is associated with the insufficient effectiveness of the developed candidates, the difficulties of their biotechnological production, and inadequate batch-to-batch reproducibility. Targeted protein self-assembling nanoparticles circumvent this problem since proteins are encoded in DNA and the final protein product is produced in only one possible way. We believe that the combination of the endless biomedical potential of protein carriers as nanoparticles and the standardized protein purification protocols will make significant progress in "magic bullet" creation possible, bringing modern biomedicine to a new level. In this review, we are focused on the currently existing platforms for targeted self-assembling protein nanoparticles based on transferrin, lactoferrin, casein, lumazine synthase, albumin, ferritin, and encapsulin proteins, as well as on proteins from magnetosomes and virus-like particles. The applications of these self-assembling proteins for targeted delivery in vitro and in vivo are thoroughly discussed, including bioimaging applications and different therapeutic approaches, such as chemotherapy, gene delivery, and photodynamic and photothermal therapy. A critical assessment of these protein platforms' efficacy in biomedicine is provided and possible problems associated with their further development are described.

5.
Nat Commun ; 13(1): 6569, 2022 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-36323657

RESUMO

Single-stranded breaks (SSBs) are the most frequent DNA lesions threatening genomic integrity. A highly kinked DNA structure in complex with human PARP-1 domains led to the proposal that SSB sensing in Eukaryotes relies on dynamics of both the broken DNA double helix and PARP-1's multi-domain organization. Here, we directly probe this process at the single-molecule level. Quantitative smFRET and structural ensemble calculations reveal how PARP-1's N-terminal zinc fingers convert DNA SSBs from a largely unperturbed conformation, via an intermediate state into the highly kinked DNA conformation. Our data suggest an induced fit mechanism via a multi-domain assembly cascade that drives SSB sensing and stimulates an interplay with the scaffold protein XRCC1 orchestrating subsequent DNA repair events. Interestingly, a clinically used PARP-1 inhibitor Niraparib shifts the equilibrium towards the unkinked DNA conformation, whereas the inhibitor EB47 stabilizes the kinked state.


Assuntos
Quebras de DNA de Cadeia Simples , Inibidores de Poli(ADP-Ribose) Polimerases , Humanos , Proteína 1 Complementadora Cruzada de Reparo de Raio-X/metabolismo , Reparo do DNA , Dano ao DNA , DNA/metabolismo
6.
Materials (Basel) ; 15(19)2022 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-36234321

RESUMO

During mining, only 4-8% is converted to final products, and the rest is accumulated in landfills. There is a lack of research on the study of various patterns and mechanisms of the formation of cement clinker minerals during the simultaneous distillation of zinc. This paper presents studies of thermodynamic stimulation of environmental and population protection by utilization of technogenic enrichment waste as secondary raw materials for clinker production and zinc extraction. In particular, a comparison of the Gibbs energy (ΔG) of clinker formation under standard chemical equations and under non-standard chemical equations is given. According to the results of the study, using thermodynamic simulation, the temperature intervals of mineral formation, the dependence of the Gibbs energy on temperature (ΔGT°), and the approximation equations were found; it was established that the presence of zinc ferrite contributes to the intensification of the formation of clinker minerals and the extraction of Zn to gas.

7.
Materials (Basel) ; 15(7)2022 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-35407873

RESUMO

This paper presents studies on the possibility of utilization of technogenic waste from the metallurgical industry by the method of complex processing in order to reduce the anthropogenic load on the environment of the region with the example of the zinc silicate-magnetite-carbon system. The selected sample of clinker dump from welting was subjected to chemical and scanning electron microscopic analyses and thermodynamic modeling. Thermodynamic studies were carried out in the temperature range 1600-2200 K and pressure p = 0.1 MPa, modeling the process of electric melting of clinker from welting in an arc furnace using the software application Astra 4 developed at the Bauman Moscow State Technical University (Moscow, Russian Federation). As a result of the thermodynamic modeling, the optimal temperature range was established, which was 1800-1900 K. Thermodynamic studies established that it is possible to drive away zinc from the system under study by 99-100% in the entire temperature range under study. The maximum degree of silicon extraction (αSi) in the alloy is up to 69.44% at T = 1900 K, and the degree of iron extraction (αFe) in the alloy is up to 99.996%. In particular, it was determined and proved that clinker waste from welting can act as a secondary technogenic raw material when it is processed as a mono mixture to produce iron silicides with a silicon content of 18 to 28%.

8.
Materials (Basel) ; 15(7)2022 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-35407915

RESUMO

The paper studies the properties of brass workpieces for antifriction rings under severe plastic deformation by high-pressure torsion. The evolution of microstructure and mechanical properties of deformed workpieces after six cycles of deformation by high-pressure torsion at 500 °C have been studied. All metallographic studies were performed using modern methods: transmission electron microscopy (TEM) and analysis electron back scatter diffraction patterns (EBSD). The deformation resulted in an ultrafine grained structure with a large number of large-angle boundaries. The strength properties of brass increased compared to the initial state almost by three times, the microhardness also increases by three times, i.e., increased from 820 MPa in the initial state to 2115 MPa after deformation. In this case, the greatest increase in strength properties occurs in the first two cycles of deformation.

11.
Sci Rep ; 12(1): 2030, 2022 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-35132103

RESUMO

The Baculovirus/insect cell expression system is a powerful technology for reconstitution of eukaryotic macromolecular assemblies. Most multigene expression platforms rely on Tn7-mediated transposition for transferring the expression cassette into the baculoviral genome. This allows a rigorous characterization of recombinant bacmids but involves multiple steps, a limitation when many constructs are to be tested. For parallel expression screening and potential high throughput applications, we have established an open source multigene-expression toolbox exploiting homologous recombination, thus reducing the recombinant baculovirus generation to a single-step procedure and shortening the time from cloning to protein production to 2 weeks. The HR-bac toolbox is composed of a set of engineered bacmids expressing a fluorescent marker to monitor virus propagation and a library of transfer vectors. They contain single or dual expression cassettes bearing different affinity tags and their design facilitates the mix and match utilization of expression units from Multibac constructs. The overall cost of virus generation with HR-bac toolbox is relatively low as the preparation of linearized baculoviral DNA only requires standard reagents. Various multiprotein assemblies (nuclear hormone receptor heterodimers, the P-TEFb or the ternary CAK kinase complex associated with the XPD TFIIH subunit) are used as model systems to validate the toolbox presented.

12.
Materials (Basel) ; 15(1)2022 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-35009470

RESUMO

This paper presents studies on the processing of enrichment tailings as a component of a raw mixture in order to obtain cement clinker, with simultaneous distillation of zinc. Thermodynamic studies were carried out in the temperature range of 600-1600 °C using the software application "HSC Chemistry 6" developed by the metallurgical company Outokumpu (Finland). As a result of the conducted studies, we found that zinc contributes to the intensification of mineral formation of cement clinker. In particular, it was found that the formation of belite is possible in the temperature range from 990.7 to 1500 °C with Gibbs energy values of -0.01 and -323.8 kJ (which is better than the standard process by -11.4 kJ), respectively; the formation of alite is possible in the temperature range from 982.9 to 1500 °C with Gibbs energy values of -0.05 and -402.1 kJ (better than the standard process by -11.4 kJ), respectively; the formation of tricalcium aluminate is thermodynamically possible in the temperature range from 600 °C at ΔGTo = -893.8 kJ to 1500 °C at ΔGTo = -1899.3 kJ (better than the standard process by -1570.1 kJ), respectively; and the formation of four calcium aluminoferrite is possible in the temperature range from 600 °C at ΔGTo = -898.9 kJ to 1500 °C at ΔGTo = -1959.3 kJ (better than the standard process by -1570.2 kJ), respectively, with simultaneous distillation of zinc into a gaseous state for its further capture.

13.
Pharmaceutics ; 15(1)2022 Dec 24.
Artigo em Inglês | MEDLINE | ID: mdl-36678681

RESUMO

Nanoparticle-based chemotherapy is considered to be an effective approach to cancer diagnostics and therapy in modern biomedicine. However, efficient tumor targeting remains a great challenge due to the lack of specificity, selectivity, and high dosage of chemotherapeutic drugs required. A two-step targeted drug delivery strategy (DDS), involving cancer cell pre-targeting, first with a first nontoxic module and subsequent targeting with a second complementary toxic module, is a solution for decreasing doses for administration and lowering systemic toxicity. To prove two-step DDS efficiency, we performed a direct comparison of one-step and two-step DDS based on chemotherapy loaded PLGA nanoparticles and barnase*barstar interface. Namely, we developed and thoroughly characterized the two-step targeting strategy of HER2-overexpressing cancer cells. The first targeting block consists of anti-HER2 scaffold polypeptide DARPin9_29 fused with barstar. Barstar exhibits an extremely effective binding to ribonuclease barnase with Kaff = 1014 M-1, thus making the barnase*barstar protein pair one of the strongest known protein*protein complexes. A therapeutic PLGA-based nanocarrier coupled to barnase was used as a second targeting block. The PLGA nanoparticles were loaded with diagnostic dye, Nile Blue, and a chemotherapeutic drug, doxorubicin. We showed that the two-step DDS increases the performance of chemotherapy-loaded nanocarriers: IC50 of doxorubicin delivered via two-step DDS was more than 100 times lower than that for one-step DDS: IC50 = 43 ± 3 nM for two-step DDS vs. IC50 = 4972 ± 1965 nM for one-step DDS. The obtained results demonstrate the significant efficiency of two-step DDS over the classical one-step one. We believe that the obtained data will significantly change the direction of research in developing targeted anti-cancer drugs and promote the creation of new generation cancer treatment strategies.

14.
Pharmaceutics ; 15(1)2022 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-36678721

RESUMO

The extreme aggressiveness and lethality of many cancer types appeal to the problem of the development of new-generation treatment strategies based on smart materials with a mechanism of action that differs from standard treatment approaches. The targeted delivery of nanoparticles to specific cancer cell receptors is believed to be such a strategy; however, there are no targeted nano-drugs that have successfully completed clinical trials to date. To meet the challenge, we designed an alternative way to eliminate tumors in vivo. Here, we show for the first time that the targeting of lectin-equipped polymer nanoparticles to the glycosylation profile of cancer cells, followed by photodynamic therapy (PDT), is a promising strategy for the treatment of aggressive tumors. We synthesized polymer nanoparticles loaded with magnetite and a PDT agent, IR775 dye (mPLGA/IR775). The magnetite incorporation into the PLGA particle structure allows for the quantitative tracking of their accumulation in different organs and the performing of magnetic-assisted delivery, while IR775 makes fluorescent in vivo bioimaging as well as light-induced PDT possible, thus realizing the theranostics concept. To equip PLGA nanoparticles with targeting modality, the particles were conjugated with lectins of different origins, and the flow cytometry screening revealed that the most effective candidate for breast cancer cell labeling is ConA, a lectin from Canavalia ensiformis. In vivo experiments showed that after i.v. administration, mPLGA/IR775-ConA nanoparticles efficiently accumulated in the allograft tumors under the external magnetic field; produced a bright fluorescent signal for in vivo bioimaging; and led to 100% tumor growth inhibition after the single session of PDT, even for large solid tumors of more than 200 mm3 in BALB/c mice. The obtained results indicate that the mPLGA/IR775 nanostructure has great potential to become a highly effective oncotheranostic agent.

15.
ACS Omega ; 6(24): 16000-16008, 2021 Jun 22.
Artigo em Inglês | MEDLINE | ID: mdl-34179645

RESUMO

Targeted drug delivery is one of the most intriguing and challenging issues in modern biomedicine. For active targeting, full-size IgG molecules (150 kDa) are usually used. Recent studies have revealed that small artificial polypeptide scaffolds such as DARPins (14 kDa) and affibodies (8 kDa) are much more promising tools for drug delivery due to their small size, artificial nature, low immunogenicity, and many other properties. However, there is no comparative information on the targeting abilities of scaffold polypeptides, which should be taken into account when developing drug delivery systems (DDSs). The present work is the first comprehensive study on the comparison of the effectiveness of different HER2-targeting proteins within the architecture of nanoparticles. Namely, we synthesized trimodal nanoparticles: magnetic, fluorescent, and directed toward HER2 oncomarker on cancer cells. The magnetic particles (MPs) were covalently modified with (i) full-size IgG, 150 kDa, (ii) DARPin_G3, 14 kDa, and (iii) affibody ZHER2:342, 8 kDa. We showed that the number of DARPin_G3 and affibody ZHER2:342 molecules conjugated to the nanoparticle surface are 10 and 40 times higher, respectively, than the corresponding value for trastuzumab. Using the methods of magnetic particle quantification (MPQ)-cytometry and confocal microscopy, we showed that all types of the obtained magnetic conjugates specifically labeled HER2-overexpressing cells. Namely, we demonstrated that particle binding to HER2-positive cells is 1113 ± 39 fg/cell for MP*trastuzumab, 1431 ± 186 fg/cell for MP*ZHER2:342, and 625±21 fg/cell for MP*DARPin_G3, which are 2.77, 2.75, and 2.30 times higher than the corresponding values for control HER2-negative cells. Thus, we showed that the smallest HER2-recognizing polypeptide affibody ZHER2:342 is more effective in terms of specificity and selectivity in nanoparticle-mediated cell labeling.

16.
C R Biol ; 343(3): 247-255, 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33621454

RESUMO

The transcription of eukaryotic protein genes is controlled by a plethora of proteins which act together in multi-component complexes to facilitate the DNA dependent RNA polymerase II (Pol II) enzyme to bind to the transcription start site and to generate messenger RNA from the gene's coding sequence. The protein that guides the transcription machinery to the exact transcription start site is called TATA-box Binding Protein, or TBP. TBP is part of two large protein complexes involved in Pol II transcription, TFIID and SAGA. The two complexes share several subunits implicated in the interaction with TBP and contain proteins with structural elements highly homologous to nucleosomal histones. Despite the intensive study of transcription initiation, the mode of interaction of TBP with these complexes and its release upon DNA binding was elusive. In this study we demonstrate the quasi-atomic model of SAGA in complex with TBP. The structure reveals the intricate network of interactions that coordinate the different functional domains of SAGA and resolves a deformed octamer of histone-fold domains at the core of SAGA. This deformed octamer is precisely tuned to establish a peripheral site for TBP binding, where it is protected by steric hindrance against the binding of spurious DNA. Complementary biochemical analysis points to a mechanism for TBP delivery and release from SAGA that requires the general transcription factor TFIIA and whose efficiency correlates with the affinity of DNA to TBP.As the TBP binding machinery is highly similar in TFIID and SAGA, we demonstrated a universal mechanism of how TBP is delivered to gene promoters during transcription initiation.


La transcription des gènes des protéines eucaryotes est contrôlée par une pléthore de protéines agissant de concert sous forme de complexes multi-composants pour faciliter la liaison de l'enzyme ARN polymérase II ADN-dépendante (Pol II) au site d'initiation de la transcription et pour générer un ARN messager à partir de la séquence codante du gène. La protéine qui guide la machinerie de transcription vers le site d'initiation de la transcription est appelée protéine de liaison à la boîte TATA, ou TBP. TBP fait partie de deux complexes protéiques impliqués dans la transcription par la Pol II, TFIID et SAGA. Les deux complexes partagent plusieurs sous-unités impliquées dans l'interaction avec TBP et comportent des protéines présentant des éléments structuraux hautement homologues aux histones nucléosomiques. Malgré l'étude intensive de l'initiation de la transcription, le mode d'interaction de TBP avec ces complexes ainsi que sa libération lors de sa liaison de l'ADN étaient évasifs. Dans cette étude, nous avons déterminé un modèle quasi-atomique de SAGA en complexe avec TBP. La structure révèle le réseau d'interactions qui coordonnent les différents domaines fonctionnels de SAGA et résout un octamère déformé des domaines homologues aux histones au cœur de SAGA. Cet octamère déformé est précisément adapté pour établir un site périphérique de liaison à TBP, où ce dernier est protégé par une inhibition stérique contre la fixation d'un ADN parasite. L'analyse biochimique complémentaire a mis en évidence un mécanisme de libération de TBP de SAGA qui nécessite le facteur de transcription général TFIIA et dont l'efficacité corrèle avec l'affinité de l'ADN pour TBP.Comme le mécanisme de liaison de TBP est très similaire dans TFIID et SAGA, nous avons mis en évidence un mécanisme universel décrivant la manière dont TBP est délivré aux promoteurs de gènes lors de l'initiation de la transcription.


Assuntos
Transativadores , Fatores de Transcrição , Regiões Promotoras Genéticas , Proteína de Ligação a TATA-Box/genética , Proteína de Ligação a TATA-Box/metabolismo , Transativadores/metabolismo , Fatores de Transcrição/genética , Transcrição Gênica
17.
Methods Mol Biol ; 2247: 17-38, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33301110

RESUMO

Most cellular processes are mediated by multi-subunit protein complexes which have attracted major interest in both academia and industry. Recombinant production of such entities in quantity and quality sufficient for functional and structural investigations may be extremely challenging and necessitate specific technologies. The baculovirus expression vector system is widely used for the production of eukaryotic multiprotein complexes, and a variety of strategies are available to assemble transfer vectors for the generation of recombinant baculoviruses. Here we detail applications of homology-based cloning techniques for one-step construction of dual promoter baculovirus transfer plasmids and of restriction-free (RF) cloning for the modification of existing constructs.


Assuntos
Baculoviridae/genética , Expressão Gênica , Vetores Genéticos/genética , Complexos Multiproteicos/biossíntese , Complexos Multiproteicos/genética , Proteínas Recombinantes , Sequência de Bases , Linhagem Celular , Células Cultivadas , Clonagem Molecular/métodos , Ordem dos Genes , Complexos Multiproteicos/química , Plasmídeos/genética , Regiões Promotoras Genéticas , Proteínas Recombinantes de Fusão
18.
Nature ; 577(7792): 711-716, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31969704

RESUMO

SAGA (Spt-Ada-Gcn5-acetyltransferase) is a 19-subunit complex that stimulates transcription via two chromatin-modifying enzymatic modules and by delivering the TATA box binding protein (TBP) to nucleate the pre-initiation complex on DNA, a pivotal event in the expression of protein-encoding genes1. Here we present the structure of yeast SAGA with bound TBP. The core of the complex is resolved at 3.5 Å resolution (0.143 Fourier shell correlation). The structure reveals the intricate network of interactions that coordinate the different functional domains of SAGA and resolves an octamer of histone-fold domains at the core of SAGA. This deformed octamer deviates considerably from the symmetrical analogue in the nucleosome and is precisely tuned to establish a peripheral site for TBP, where steric hindrance represses binding of spurious DNA. Complementary biochemical analysis points to a mechanism for TBP delivery and release from SAGA that requires transcription factor IIA and whose efficiency correlates with the affinity of DNA to TBP. We provide the foundations for understanding the specific delivery of TBP to gene promoters and the multiple roles of SAGA in regulating gene expression.


Assuntos
Proteínas Fúngicas/química , Proteínas Fúngicas/metabolismo , Pichia , Regiões Promotoras Genéticas/genética , Proteína de Ligação a TATA-Box/metabolismo , Transativadores/química , Transativadores/metabolismo , Sítios de Ligação , DNA Fúngico/química , DNA Fúngico/metabolismo , Regulação Fúngica da Expressão Gênica , Histona Acetiltransferases/química , Histona Acetiltransferases/metabolismo , Histonas/química , Histonas/metabolismo , Modelos Moleculares , Pichia/química , Pichia/genética , Ligação Proteica , Conformação Proteica , Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores Associados à Proteína de Ligação a TATA/química , Fatores Associados à Proteína de Ligação a TATA/metabolismo , Proteína de Ligação a TATA-Box/química , Fator de Transcrição TFIIA/química , Fator de Transcrição TFIIA/metabolismo , Fator de Transcrição TFIID/química , Fator de Transcrição TFIID/metabolismo
19.
Adv Protein Chem Struct Biol ; 115: 21-67, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30798933

RESUMO

Transcription factor IIH (TFIIH) is a multiprotein complex involved in both eukaryotic transcription and DNA repair, revealing a tight connection between these two processes. Composed of 10 subunits, it can be resolved into a 7-subunits core complex with the XPB translocase and the XPD helicase, and the 3-subunits kinase complex CAK, which also exists as a free complex with a distinct function. Initially identified as basal transcription factor, TFIIH also participates in transcription regulation and plays a key role in nucleotide excision repair (NER) for opening DNA at damaged sites, lesion verification and recruitment of additional repair factors. Our understanding of TFIIH function in eukaryotic cells has greatly benefited from studies of the genetic rare diseases xeroderma pigmentosum (XP), Cockayne syndrome (CS) and trichothiodystrophy (TTD), that are not only characterized by cancer and aging predispositions but also by neurological and developmental defects. Although much remains unknown about TFIIH function, significant progresses have been done regarding the structure of the complex, the functions of its catalytic subunits and the multiple roles of the regulatory core-TFIIH subunits. This review provides a non-exhaustive survey of key discoveries on the structure and function of this pivotal factor, which can be considered as a promising target for therapeutic strategies.


Assuntos
Reparo do DNA , Fator de Transcrição TFIIH/metabolismo , Transcrição Gênica , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/genética , Neoplasias/metabolismo , Bibliotecas de Moléculas Pequenas/farmacologia , Fator de Transcrição TFIIH/antagonistas & inibidores , Transcrição Gênica/efeitos dos fármacos
20.
Nat Commun ; 9(1): 4666, 2018 11 07.
Artigo em Inglês | MEDLINE | ID: mdl-30405110

RESUMO

Transcription preinitiation complex assembly on the promoters of protein encoding genes is nucleated in vivo by TFIID composed of the TATA-box Binding Protein (TBP) and 13 TBP-associate factors (Tafs) providing regulatory and chromatin binding functions. Here we present the cryo-electron microscopy structure of promoter-bound yeast TFIID at a resolution better than 5 Å, except for a flexible domain. We position the crystal structures of several subunits and, in combination with cross-linking studies, describe the quaternary organization of TFIID. The compact tri lobed architecture is stabilized by a topologically closed Taf5-Taf6 tetramer. We confirm the unique subunit stoichiometry prevailing in TFIID and uncover a hexameric arrangement of Tafs containing a histone fold domain in the Twin lobe.


Assuntos
Regiões Promotoras Genéticas/genética , Fator de Transcrição TFIID/química , Fator de Transcrição TFIID/metabolismo , Leveduras/metabolismo , DNA Fúngico/química , DNA Fúngico/metabolismo , Modelos Moleculares , Ligação Proteica , Subunidades Proteicas/química , Subunidades Proteicas/isolamento & purificação , Subunidades Proteicas/metabolismo , Saccharomyces cerevisiae/metabolismo , Fator de Transcrição TFIID/isolamento & purificação
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