RESUMEN
Old age is a crucial risk factor for severe coronavirus disease 2019 (COVID-19), with serious or fatal outcomes disproportionately affecting older adults compared with the rest of the population. We proposed that the physiological health status and biological age, beyond the chronological age itself, could be the driving trends affecting COVID-19 severity and mortality. A total of 155 participants hospitalized with confirmed COVID-19 aged 26-94 years were recruited for the study. Four different physiological summary indices were calculated: Klemera and Doubal's biological age, PhenoAge, physiological dysregulation (PD; globally and in specific systems), and integrated albunemia. All of these indices significantly predicted the risk of death (p < 0.01) after adjusting for chronological age and sex. In all models, men were 2.4-4.4-times more likely to die than women. The global PD was shown to be a good predictor of deterioration, with the odds of deterioration increasing by 41.7% per 0.5-unit increase in the global PD. As for death, the odds also increased by 68.3% per 0.5-unit increase in the global PD. Our results are partly attributed to common chronic diseases that aggravate COVID-19, but they also suggest that the underlying physiological state could capture vulnerability to severe COVID-19 and serve as a tool for prognosis that would, in turn, help inpatient management.
Asunto(s)
COVID-19/mortalidad , COVID-19/fisiopatología , Estado de Salud , Adulto , Anciano , Anciano de 80 o más Años , Envejecimiento , Femenino , Humanos , Masculino , Persona de Mediana EdadRESUMEN
The heterotrimeric archaeal IF2 orthologue of eukaryotic translation initiation factor 2 consists of the α-subunit, ß-subunit and γ-subunit. Previous studies showed that the γ-subunit of aIF2, besides its central role in Met-tRNAi binding, has an additional function: it binds to the 5'-triphosphorylated end of mRNA and protects its 5'-part from degradation. Competition studies with nucleotides and mRNA, as well as structural and kinetic analyses of aIF2γ mutants, strongly implicate the canonical GTP/GDP-binding pocket in binding to the 5'-triphosphate end of mRNAs. The biological implication of these findings is being discussed.
Asunto(s)
Factores de Iniciación de Péptidos/metabolismo , ARN Mensajero/metabolismo , Sulfolobus solfataricus/metabolismo , Sitios de Unión , Cristalografía por Rayos X , Guanosina Trifosfato/metabolismo , Simulación del Acoplamiento Molecular , Simulación de Dinámica Molecular , Factores de Iniciación de Péptidos/química , Subunidades de Proteína , ARN de Archaea/química , ARN de Archaea/metabolismo , ARN Mensajero/química , Sulfolobus solfataricus/químicaRESUMEN
The human YB-1 protein plays multiple cellular roles, of which many are dictated by its binding to RNA and DNA through its Cold Shock Domain (CSD). Using molecular dynamics simulation approaches validated by experimental assays, the YB1 CSD was found to interact with nucleic acids in a sequence-dependent manner and with a higher affinity for RNA than DNA. The binding properties of the YB1 CSD were close to those observed for the related bacterial Cold Shock Proteins (CSP), albeit some differences in sequence specificity. The results provide insights in the molecular mechanisms whereby YB-1 interacts with nucleic acids.
Asunto(s)
Proteínas y Péptidos de Choque por Frío/genética , ADN/genética , ARN/genética , Proteína 1 de Unión a la Caja Y/genética , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Sitios de Unión/genética , Proteínas de Unión al ADN/genética , Humanos , Simulación de Dinámica Molecular , Datos de Secuencia Molecular , Ácidos Nucleicos/genética , Estructura Terciaria de Proteína , Proteínas de Unión al ARN/genética , Alineación de SecuenciaRESUMEN
The formation of a specific and stable complex between two (macro)molecules implies complementary contact surface regions. We used ribosomal protein L1, which specifically binds a target site on 23S rRNA, to study the influence of surface modifications on the protein-RNA affinity. The threonine residue in the universally conserved triad Thr-Met-Gly significant for RNA recognition and binding was substituted by phenylalanine, valine and alanine, respectively. The crystal structure of the mutant Thr217Val of the isolated domain I of L1 from Thermus thermophilus (TthL1) was determined. This structure and that of two other mutants, which had been determined earlier, were analysed and compared with the structure of the wild type L1 proteins. The influence of structural changes in the mutant L1 proteins on their affinity for the specific 23S rRNA fragment was tested by kinetic experiments using surface plasmon resonance (SPR) biosensor analysis. Association rate constants undergo minor changes, whereas dissociation rate constants displayed significantly higher values in comparison with that for the wild type protein. The analysed L1 mutants recognize the specific RNA target site, but the mutant L1-23S rRNA complexes are less stable compared to the wild type complexes.
Asunto(s)
ARN Ribosómico 23S/metabolismo , Proteínas Ribosómicas/química , Proteínas Ribosómicas/metabolismo , Secuencia de Aminoácidos , Sitios de Unión/genética , Sitios de Unión/fisiología , Cinética , Simulación de Dinámica Molecular , Datos de Secuencia Molecular , Unión Proteica/genética , Unión Proteica/fisiología , Estructura Secundaria de Proteína , ARN Ribosómico 23S/genética , Proteínas Ribosómicas/genética , Homología de Secuencia de Aminoácido , Resonancia por Plasmón de Superficie/métodos , Thermus thermophilus/genética , Thermus thermophilus/metabolismoRESUMEN
The two-domain ribosomal protein L1 has a dual function as a primary rRNA-binding ribosomal protein and as a translational repressor that binds its own mRNA. Here, we report the crystal structure of a complex between the isolated domain I of L1 from the bacterium Thermus thermophilus and a specific mRNA fragment from Methanoccocus vannielii. In parallel, we report kinetic characteristics measured for complexes formed by intact TthL1 and its domain I with the specific mRNA fragment. Although, there is a close similarity between the RNA-protein contact regions in both complexes, the association rate constant is higher in the case of the complex formed by the isolated domain I. This finding demonstrates that domain II hinders mRNA recognition by the intact TthL1.
Asunto(s)
Proteínas Bacterianas/química , ARN Bacteriano/metabolismo , ARN Mensajero/metabolismo , Proteínas Ribosómicas/química , Thermus thermophilus/metabolismo , Secuencia de Aminoácidos , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Sitios de Unión , Cristalografía por Rayos X , Cinética , Methanococcus/genética , Methanococcus/metabolismo , Modelos Moleculares , Datos de Secuencia Molecular , Estructura Terciaria de Proteína , ARN Bacteriano/química , ARN Mensajero/química , Proteínas Ribosómicas/genética , Proteínas Ribosómicas/metabolismo , Thermus thermophilus/genéticaRESUMEN
Ribosomal protein L1 has a dual function as a ribosomal protein binding 23S rRNA and as a translational repressor binding its mRNA. L1 is a two-domain protein with N- and C-termini located in domain I. Earlier it was shown that L1 interacts with the same targets on both rRNA and mRNA mainly through domain I. We have suggested that domain I is necessary and sufficient for specific RNA-binding by L1. To test this hypothesis, a truncation mutant of L1 from Thermus thermophilus, representing domain I, was constructed by deletion of the central part of the L1 sequence, which corresponds to domain II. It was shown that the isolated domain I forms stable complexes with specific fragments of both rRNA and mRNA. The crystal structure of the isolated domain I was determined and compared with the structure of this domain within the intact protein L1. This comparison revealed a close similarity of both structures. Our results confirm our suggestion that in protein L1 its domain I alone is sufficient for specific RNA binding, whereas domain II stabilizes the L1-rRNA complex.
Asunto(s)
Proteínas Bacterianas/química , ARN Mensajero/metabolismo , ARN Ribosómico 23S/metabolismo , Proteínas Ribosómicas/química , Secuencia de Aminoácidos , Sitios de Unión , Cristalografía por Rayos X , Modelos Moleculares , Datos de Secuencia Molecular , Unión Proteica , Estructura Terciaria de Proteína , Proteínas Ribosómicas/metabolismo , Thermus thermophilusRESUMEN
The RNA-binding ability of ribosomal protein L1 is of profound interest, since L1 has a dual function as a ribosomal structural protein that binds rRNA and as a translational repressor that binds its own mRNA. Here, we report the crystal structure at 2.6 A resolution of ribosomal protein L1 from the bacterium Thermus thermophilus in complex with a 38 nt fragment of L1 mRNA from Methanoccocus vannielii. The conformation of RNA-bound T.thermophilus L1 differs dramatically from that of the isolated protein. Analysis of four copies of the L1-mRNA complex in the crystal has shown that domain II of the protein does not contribute to mRNA-specific binding. A detailed comparison of the protein-RNA interactions in the L1-mRNA and L1-rRNA complexes identified amino acid residues of L1 crucial for recognition of its specific targets on the both RNAs. Incorporation of the structure of bacterial L1 into a model of the Escherichia coli ribosome revealed two additional contact regions for L1 on the 23S rRNA that were not identified in previous ribosome models.