RESUMO
Inorganic polyphosphates (polyPs) are linear polymers composed of repeated phosphate (PO4 3-) units linked together by multiple high-energy phosphoanhydride bonds. In addition to being a source of energy, polyPs have cytoprotective and antiviral activities. Here, we investigated the antiviral activities of long-chain polyPs against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. In molecular docking analyses, polyPs interacted with several conserved amino acid residues in angiotensin-converting enzyme 2 (ACE2), the host receptor that facilitates virus entry, and in viral RNA-dependent RNA polymerase (RdRp). ELISA and limited proteolysis assays using nano- LC-MS/MS mapped polyP120 binding to ACE2, and site-directed mutagenesis confirmed interactions between ACE2 and SARS-CoV-2 RdRp and identified the specific amino acid residues involved. PolyP120 enhanced the proteasomal degradation of both ACE2 and RdRp, thus impairing replication of the British B.1.1.7 SARS-CoV-2 variant. We thus tested polyPs for functional interactions with the virus in SARS-CoV-2-infected Vero E6 and Caco2 cells and in primary human nasal epithelial cells. Delivery of a nebulized form of polyP120 reduced the amounts of viral positive-sense genomic and subgenomic RNAs, of RNA transcripts encoding proinflammatory cytokines, and of viral structural proteins, thereby presenting SARS-CoV-2 infection in cells in vitro.
Assuntos
Antivirais/farmacologia , Tratamento Farmacológico da COVID-19 , Polifosfatos/farmacologia , SARS-CoV-2/efeitos dos fármacos , Administração por Inalação , Sequência de Aminoácidos , Enzima de Conversão de Angiotensina 2/química , Enzima de Conversão de Angiotensina 2/metabolismo , Animais , Antivirais/administração & dosagem , Antivirais/química , COVID-19/metabolismo , COVID-19/virologia , Células CACO-2 , Chlorocebus aethiops , RNA-Polimerase RNA-Dependente de Coronavírus/química , RNA-Polimerase RNA-Dependente de Coronavírus/genética , RNA-Polimerase RNA-Dependente de Coronavírus/metabolismo , Citocinas/metabolismo , Células HEK293 , Interações entre Hospedeiro e Microrganismos/efeitos dos fármacos , Interações entre Hospedeiro e Microrganismos/genética , Interações entre Hospedeiro e Microrganismos/fisiologia , Humanos , Técnicas In Vitro , Modelos Biológicos , Simulação de Acoplamento Molecular , Nebulizadores e Vaporizadores , Polifosfatos/administração & dosagem , Polifosfatos/química , Complexo de Endopeptidases do Proteassoma/metabolismo , Domínios e Motivos de Interação entre Proteínas , Proteólise/efeitos dos fármacos , RNA Viral/genética , RNA Viral/metabolismo , SARS-CoV-2/genética , SARS-CoV-2/fisiologia , Homologia de Sequência de Aminoácidos , Transdução de Sinais/efeitos dos fármacos , Células Vero , Replicação Viral/efeitos dos fármacosRESUMO
Nitrate is an essential element for plant growth, both as a primary nutrient in the nitrogen assimilation pathway and as an important signal for plant development. Low- and high-affinity transport systems are involved in the nitrate uptake from the soil and its distribution between different plant tissues. By an in silico search, we identified putative members of both systems in the model legume Lotus japonicus. We investigated, by a time course analysis, the transcripts abundance in root tissues of nine and four genes encoding putative low-affinity (NRT1) and high-affinity (NRT2) nitrate transporters, respectively. The genes were sub-classified as inducible, repressible and constitutive on the basis of their responses to provision of nitrate, auxin or cytokinin. Furthermore, the analysis of the pattern of expression in root and nodule tissues after Mesorhizobium loti inoculation permitted the identification of sequences significantly regulated during the symbiotic interaction. The interpretation of the global regulative networks obtained allowed to postulate roles for nitrate transporters as possible actors in the cross-talks between different signalling pathways triggered by biotic and abiotic factors.
