Insights into the specificity for the interaction of the promiscuous SARS-CoV-2 nucleocapsid protein N-terminal domain with deoxyribonucleic acids.

The SARS-CoV-2 nucleocapsid protein (N) is a multifunctional promiscuous nucleic acid-binding protein, which plays a major role in nucleocapsid assembly and discontinuous RNA transcription, facilitating the template switch of transcriptional regulatory sequences (TRS). Here, we dissect the structural features of the N protein N-terminal domain (N-NTD) and N-NTD plus the SR-rich motif (N-NTD-SR) upon binding to single and double-stranded TRS DNA, as well as their activities for dsTRS melting and TRS-induced liquid-liquid phase separation (LLPS). Our study gives insights on the specificity for N-NTD(-SR) interaction with TRS. We observed an approximation of the triple-thymidine (TTT) motif of the TRS to ß-sheet II, giving rise to an orientation difference of ~25° between dsTRS and non-specific sequence (dsNS). It led to a local unfavorable energetic contribution that might trigger the melting activity. The thermodynamic parameters of binding of ssTRSs and dsTRS suggested that the duplex dissociation of the dsTRS in the binding cleft is entropically favorable. We showed a preference for TRS in the formation of liquid condensates when compared to NS. Moreover, our results on DNA binding may serve as a starting point for the design of inhibitors, including aptamers, against N, a possible therapeutic target essential for the virus infectivity.

The 1H, 15N, and 13C resonance assignments of the N-terminal domain of the nucleocapsid protein from the Middle East respiratory syndrome coronavirus.

During the past 17 years, the coronaviruses have become a global public emergency, with the first appearance in 2012 in Saudi Arabia of the Middle East respiratory syndrome. Among the structural proteins encoded in the viral genome, the nucleocapsid protein is the most abundant in infected cells. It is a multifunctional phosphoprotein involved in the capsid formation, in the modulation and regulation of the viral life cycle. The N-terminal domain of N protein specifically interacts with transcriptional regulatory sequence (TRS) and is involved in the discontinuous transcription through the melting activity of double-stranded TRS (dsTRS).

High dilutions of euphorbia tirucalli L. (aveloz) modify the viability and glycolytic metabolism of cell lines / Altas diluições de Euphorbia tirucalli L. (aveloz) modificam a viabilidade e o metabolismo glicolítico de linhas celulares

The latex of Euphorbia tirucalli L. (Aveloz) is popularly used to treat cancers from diverse sources such as: breast, prostate, lung and kidney. Furthermore, high dilutions of this latex (latex-HDs) have been successfully used in the treatment of tumors, although the mechanisms involved in this antitumoral activity are not yet known [...] Latex-HDs were obtained through the interaction of two procedures: 1:100 dilution in mass and agitation, using 2 solvents, water and 70% ethanol in homeopathic preparations 5, 15 and 30cH, following the Brazilian Homeopathic Pharmacopeia. Cell lines were incubated with 1 % and 10 % of latex-HDs for 24 hours. Controls treated with similar preparations without latex were incubated under the same conditions. Cell viability was analyzed by MTT assay and morphological features were assessed by May-Grunwald-Giemsa method. Cell ultrastructure was analyzed by transmission electron microscopy. Metabolic alterations were detected by spectrophotometric assay for the enzyme 6-phosphofructo-1-kinase (PFK-1) activity. 1% of ethanolic latex-HDs induced no alterations in MelanA cells viability, however Aveloz 15cH induced an increase in MCF7 cells viability. After aqueous treatment, MelanA cells viability decreased in almost all systems, whereas in MCF7 cells, an increase was detected in dynamized water systems and Aveloz 15CH. However, only water 15cH increased cell viability in comparison to control and non-dynamized water. No alterations in MCF7 morphology and ultrastructure were visualized through light microscopy or electronic microscopy, respectively. Interesting results were detected when we studied the glycolytic metabolism of both cells, giving support to evidences showing that HDs interfere in the metabolism of cell lines. Further studies are needed to better understand the mechanisms involved in this in vitro biological response to HDs.(AU)

O látex de Ephorbia tirucalli L. (aveloz) é usado popularmente no tratamento de diversos tipos de câncer incluindo mama, próstata, pulmão e rim. Além do mais, altas diluições desse látex (latex-HDs) têm sido utilizadas com sucesso no tratamento de tumores, embora o mecanismo dessa ação ainda seja desconhecido [...] As látex-HDs foram obtidas através de 2 procedimentos: diluição 1:100 em massa e agitação, com 2 solventes, água e etanol 70%, nas diluições homeopáticas 5, 15cH e 30cH de acordo com a Farmacopéia Homeopática Brasileira. As linhas celulares foram incubadas com látex-HDs 1% e 10% por 24 horas. Foram preparados controles similares sem o látex e incubados sob as mesmas condições. A viabilidade celular foi analisada através do método May-grunwald-Giemsa. A ultrastrutura celular foi analisada através de microscopia eletrônica de transmissão. As alterações metabólicas foram detectadas por ensaio de espectrofotometria para a atividade da anzima 6-fosfofructo-1-quinase (PFK-1). Látex-Hds em etanol 1% não induziram qualquer alteração na viabilidade das células MelanA, mas Aveloz 15cH induziu aumento da viabilidade das células MCF7. Após tratamento, a viabilidade das células MelanA diminuiu em quase todos os sistemas, enquanto que nas células MCF7 foi detectado aumento nos sistemas aquosos e Aveloz 15cH, mas só água 15cH aumentou a viabilidade celular por comparação ao controle e agua não dinamizada. Não foram detectadas alterações na morfologia celular por microscopis de luz quando se estudou o metabolismo glicolítico em ambas as células, demonstrando que os padrões de resposta celular dependem do tipo de solvente, metabolismo celular e procedimento de diluição. esa é a primeira vez que se mostra que as altas diluições interferem no metabolismo de linhas celulares. Outros estudos são necessários para se compreender melhor os mecanismos envolvidos nesta resposta in vitro a altas diluições de aveloz.(AU)

High dilutions of Euphorbia tirucalli L. (aveloz) modify the viability and glycolytic metabolism of cell lines / Altas diluições de Euphorbia tirucalli L. (aveloz) modificam a viabilidade e o metabolismo glicolítico de linhas celulares

The latex of Euphorbia tirucalli L. (Aveloz) is popularly used to treat cancers from diverse sources such as: breast, prostate, lung and kidney. Furthermore, high dilutions of this latex (latex-HDs) have been successfully used in the treatment of tumors, although the mechanisms involved in this antitumoral activity are not yet known [...] Latex-HDs were obtained through the interaction of two procedures: 1:100 dilution in mass and agitation, using 2 solvents, water and 70% ethanol in homeopathic preparations 5, 15 and 30cH, following the Brazilian Homeopathic Pharmacopeia. Cell lines were incubated with 1 % and 10 % of latex-HDs for 24 hours. Controls treated with similar preparations without latex were incubated under the same conditions. Cell viability was analyzed by MTT assay and morphological features were assessed by May-Grunwald-Giemsa method. Cell ultrastructure was analyzed by transmission electron microscopy. Metabolic alterations were detected by spectrophotometric assay for the enzyme 6-phosphofructo-1-kinase (PFK-1) activity. 1% of ethanolic latex-HDs induced no alterations in MelanA cells viability, however Aveloz 15cH induced an increase in MCF7 cells viability. After aqueous treatment, MelanA cells viability decreased in almost all systems, whereas in MCF7 cells, an increase was detected in dynamized water systems and Aveloz 15CH. However, only water 15cH increased cell viability in comparison to control and non-dynamized water. No alterations in MCF7 morphology and ultrastructure were visualized through light microscopy or electronic microscopy, respectively. Interesting results were detected when we studied the glycolytic metabolism of both cells, giving support to evidences showing that HDs interfere in the metabolism of cell lines. Further studies are needed to better understand the mechanisms involved in this in vitro biological response to HDs.

O látex de Ephorbia tirucalli L. (aveloz) é usado popularmente no tratamento de diversos tipos de câncer incluindo mama, próstata, pulmão e rim. Além do mais, altas diluições desse látex (latex-HDs) têm sido utilizadas com sucesso no tratamento de tumores, embora o mecanismo dessa ação ainda seja desconhecido [...] As látex-HDs foram obtidas através de 2 procedimentos: diluição 1:100 em massa e agitação, com 2 solventes, água e etanol 70%, nas diluições homeopáticas 5, 15cH e 30cH de acordo com a Farmacopéia Homeopática Brasileira. As linhas celulares foram incubadas com látex-HDs 1% e 10% por 24 horas. Foram preparados controles similares sem o látex e incubados sob as mesmas condições. A viabilidade celular foi analisada através do método May-grunwald-Giemsa. A ultrastrutura celular foi analisada através de microscopia eletrônica de transmissão. As alterações metabólicas foram detectadas por ensaio de espectrofotometria para a atividade da enzima 6-fosfofructo-1-quinase (PFK-1). Látex-Hds em etanol 1% não induziram qualquer alteração na viabilidade das células MelanA, mas Aveloz 15cH induziu aumento da viabilidade das células MCF7. Após tratamento, a viabilidade das células MelanA diminuiu em quase todos os sistemas, enquanto que nas células MCF7 foi detectado aumento nos sistemas aquosos e Aveloz 15cH, mas só água 15cH aumentou a viabilidade celular por comparação ao controle e água não dinamizada. Não foram detectadas alterações na morfologia celular por microscopis de luz quando se estudou o metabolismo glicolítico em ambas as células, demonstrando que os padrões de resposta celular dependem do tipo de solvente, metabolismo celular e procedimento de diluição. Esta é a primeira vez que se mostra que as altas diluições interferem no metabolismo de linhas celulares. Outros estudos são necessários para se compreender melhor os mecanismos envolvidos nesta resposta in vitro a altas diluições de aveloz.