RESUMEN
Late-life depression is common and often inadequately managed using existing therapies. Depression is also associated with increased markers of inflammation, suggesting a potential role for anti-inflammatory agents. ASPREE-D is a sub-study of ASPREE, a large multi-centre, population-based, double-blind, placebo-controlled trial of aspirin vs placebo in older Australian and American adults (median follow-up: 4.7 years) of whom 1879 were depressed at baseline. Participants were given 100 mg daily dose of aspirin or placebo. Depressive symptoms were assessed annually using the validated, self-rated short version of the Center for Epidemiological Studies Depression scale. There was a significant increase in depressive scores (0.6; 95% CI 0.2 to 0.9; χ2 (1) = 10.37; p = 0.001) and a decreased score in the mental health component of a quality of life scale (-0.7; 95% CI -1.4 to -0.1; χ2 (1) = 4.74; p = 0.029) in the aspirin group compared to the placebo group. These effects were greater in the first year of follow-up and persisted throughout the study, albeit with small to very small effect sizes. This study failed to demonstrate any benefit of aspirin in the long-term course of depression in this community-dwelling sample of older adults over a 5-year period, and identified an adverse effect of aspirin in the course of depression in those with pre-existing depressive symptoms.
Asunto(s)
Aspirina , Depresión , Anciano , Australia , Depresión/tratamiento farmacológico , Método Doble Ciego , Humanos , Calidad de VidaRESUMEN
BACKGROUND: Inflammation contributes to the pathophysiology of major depressive disorder (MDD), and anti-inflammatory strategies might therefore have therapeutic potential. This trial aimed to determine whether adjunctive aspirin or rosuvastatin, compared with placebo, reduced depressive symptoms in young people (15-25 years). METHODS: YoDA-A, Youth Depression Alleviation with Anti-inflammatory Agents, was a 12-week triple-blind, randomised, controlled trial. Participants were young people (aged 15-25 years) with moderate to severe MDD (MADRS mean at baseline 32.5 ± 6.0; N = 130; age 20.2 ± 2.6; 60% female), recruited between June 2013 and June 2017 across six sites in Victoria, Australia. In addition to treatment as usual, participants were randomised to receive aspirin (n = 40), rosuvastatin (n = 48), or placebo (n = 42), with assessments at baseline and weeks 4, 8, 12, and 26. The primary outcome was change in the Montgomery-Åsberg Depression Rating Scale (MADRS) from baseline to week 12. RESULTS: At the a priori primary endpoint of MADRS differential change from baseline at week 12, there was no significant difference between aspirin and placebo (1.9, 95% CI (- 2.8, 6.6), p = 0.433), or rosuvastatin and placebo (- 4.2, 95% CI (- 9.1, 0.6), p = 0.089). For rosuvastatin, secondary outcomes on self-rated depression and global impression, quality of life, functioning, and mania were not significantly different from placebo. Aspirin was inferior to placebo on the Quality of Life Enjoyment and Satisfaction Questionnaire (Q-LES-Q-SF) at week 12. Statins were superior to aspirin on the MADRS, the Clinical Global Impressions Severity Scale (CGI-S), and the Negative Problem Orientation Questionnaire scale (NPOQ) at week 12. CONCLUSIONS: The addition of either aspirin or rosuvastatin did not to confer any beneficial effect over and above routine treatment for depression in young people. Exploratory comparisons of secondary outcomes provide limited support for a potential therapeutic role for adjunctive rosuvastatin, but not for aspirin, in youth depression. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry, ACTRN12613000112763. Registered on 30/01/2013.
Asunto(s)
Antiinflamatorios no Esteroideos/uso terapéutico , Antiinflamatorios/uso terapéutico , Aspirina/uso terapéutico , Trastorno Depresivo Mayor/tratamiento farmacológico , Inhibidores de Hidroximetilglutaril-CoA Reductasas/provisión & distribución , Inhibidores de Hidroximetilglutaril-CoA Reductasas/uso terapéutico , Adolescente , Adulto , Femenino , Humanos , Masculino , Rosuvastatina Cálcica/uso terapéutico , Adulto JovenRESUMEN
Myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS) is a common and disabling condition with a paucity of effective and evidence-based therapies, reflecting a major unmet need. Cognitive behavioural therapy and graded exercise are of modest benefit for only some ME/CFS patients, and many sufferers report aggravation of symptoms of fatigue with exercise. The presence of a multiplicity of pathophysiological abnormalities in at least the subgroup of people with ME/CFS diagnosed with the current international consensus "Fukuda" criteria, points to numerous potential therapeutic targets. Such abnormalities include extensive data showing that at least a subgroup has a pro-inflammatory state, increased oxidative and nitrosative stress, disruption of gut mucosal barriers and mitochondrial dysfunction together with dysregulated bioenergetics. In this paper, these pathways are summarised, and data regarding promising therapeutic options that target these pathways are highlighted; they include coenzyme Q10, melatonin, curcumin, molecular hydrogen and N-acetylcysteine. These data are promising yet preliminary, suggesting hopeful avenues to address this major unmet burden of illness.
Asunto(s)
Síndrome de Fatiga Crónica/tratamiento farmacológico , Síndrome de Fatiga Crónica/patología , Animales , Humanos , Inflamación/tratamiento farmacológico , Inflamación/patología , Mucosa Intestinal/efectos de los fármacos , Estrés Nitrosativo/efectos de los fármacos , Estrés Oxidativo/efectos de los fármacosRESUMEN
The aim of this pilot randomised control trial (RCT) was to test, 1) feasibility and acceptability of a surf therapy program to improve symptoms of mental ill-health among children and adolescents, and 2) the design and procedures of an evaluative study. This pilot RCT compared a 6-week mentor-supported surf therapy program with a wait list control group, in Australian children and adolescents aged 8-18yrs (M age = 11.28, SD = 2.34; 15 females), who were help seeking for issues relating to their mental health. Exclusion criteria included if an individual was actively suicidal or experiencing a psychotic episode or being unavailable for program dates. The primary outcome was the feasibility and acceptability of the intervention and study design assessed via 11 pre-defined criteria. A secondary outcome was to investigate the effectiveness signal of the intervention on child indicators of depression and anxiety, assessed via the Revised Children's Anxiety and Depression Scale-Short Form and the Strengths and Difficulties Questionnaire. Random allocation was computer generated and while it was not possible to blind participants, researchers collecting assessments were blinded to group allocation. Thirty-six youth were randomised (intervention = 18; wait list controls = 18), representing an 84% participation rate among eligible youth. Of the 11 a priori feasibility and acceptability criteria, 4 of 5 relating to the intervention, and 4 of 6 addressing the study design were fully met, with the unmet factors guiding program revision. At the completion of the intervention, children and adolescents receiving the intervention reported reductions in symptoms of depression (ES = 0.57), anxiety (ES = 0.43), emotional problems, (ES = 0.79), peer problems (ES = 0.56), hyperactivity/inattention (ES = 0.28), and overall difficulties (ES = 0.64). These reductions were not sustained 6-weeks after completion of the intervention. Surf therapy is an acceptable and feasible intervention for addressing symptoms of mental ill-health among children and adolescents. Preliminary evidence suggests that surf therapy improves symptoms of mental ill-health in the short-term but that these improvements were not sustained after the intervention is ceased.
Asunto(s)
Ansiedad , Salud Mental , Femenino , Adolescente , Humanos , Niño , Proyectos Piloto , Australia , Ansiedad/terapia , Trastornos de AnsiedadRESUMEN
BACKGROUND: LGBQ+ people (Lesbian, Gay, Bisexual, Queer) are at-risk of discrimination and developing mental health issues within general populations. Limited research has assessed their mental health in emergency services occupations, a population which are known to experience poorer mental health. The current study explores the extent to which sexual orientation is associated with higher rates of mental health issues among emergency personnel. METHODS: A stratified random sample of employees from twenty-nine police (N = 8,088), ambulance (N = 3,473), and fire and rescue (N = 2,975) agencies from around Australia participated in a cross-sectional mental health survey (N = 14,536, male = 64.2%, 42.7% over 45 years of age, heterosexual = 92.7%). RESULTS: Employees with a bisexual/pansexual orientation or those who were not sure about their sexual orientation were significantly more likely to report suicidal thoughts, suicide plans, psychological distress, and illicit drug use when compared with heterosexual employees. LGBQ+ employees reported significantly higher rates of lifetime suicide plans and attempts. Specifically, LGBQ+ fire and rescue personnel were roughly six times more likely to report lifetime suicide attempts, and approximately five times more likely to use illicit drugs weekly than their heterosexual colleagues in the fire and rescue sector. Female LGBQ+ personnel were significantly less likely to consume illicit drugs weekly and monthly than male LGBQ+ personnel. CONCLUSIONS: Emergency services personnel are already at-risk of developing pervasive mental health difficulties. It is important that organisations foster positive working environments, particularly for LGBQ+ people who may be more marginalized within organisations.
Asunto(s)
Salud Mental , Conducta Sexual , Australia/epidemiología , Bisexualidad , Estudios Transversales , Femenino , Humanos , Masculino , PrevalenciaRESUMEN
Importance: Depression is associated with increased inflammation, which may precede its onset, especially in older people. Some preclinical data suggest potential antidepressant effects of aspirin, supported by limited observational data suggesting lower rates of depression in individuals treated with aspirin. There currently appears to be no evidence-based pharmacotherapies for the primary prevention of depression. Objective: To determine whether low-dose aspirin (100 mg) reduces the risk of depression in healthy older adults. Design, Setting, and Participants: This double-blinded, placebo-controlled randomized clinical trial was a substudy of the Aspirin in Reducing Events in the Elderly (ASPREE) trial, which examined if aspirin increased healthy life span, defined as survival free of dementia and disability. The prespecified secondary outcome was depression. Individuals of all races/ethnicities older than 70 years in Australia, as well as white individuals older than 70 years and black and Hispanic individuals older than 65 years in the United States, were included. Interventions: Participants were randomized to aspirin (100 mg daily) or placebo, with a median (interquartile range) follow-up of 4.7 (3.5-5.6) years. Main Outcomes and Measures: The primary outcome was a proxy measure of major depressive disorder defined as a score of 8 or more on the Center for Epidemiologic Studies Depression 10-item (CES-D-10) scale. Results: Of the 19â¯114 participants enrolled in the trial, 9525 received aspirin and 9589 received a placebo. The mean (SD) age was 75.2 (4.0) years in the aspirin group and 75.1 (4.5) years in the placebo group; 9531 (56.4%) were women. Participants' demographics and clinical characteristics at baseline were similar between groups. A total of 79â¯886 annual CES-D-10 measurements were taken, with a mean of 4.2 measurements per participant. There were no significant differences at annual visits in the proportions of CES-D-10 scores of 8 or more between the aspirin and placebo groups. The incidence rate of new CES-D-10 scores of 8 or more was 70.4 events per 1000 person-years in the aspirin group and 69.1 in the placebo group (hazard ratio, 1.02 [95% CI, 0.96-1.08]; P = .54). Conclusions and Relevance: Low-dose aspirin did not prevent depression in this large-scale study of otherwise healthy older adults. Trial Registration: ClinicalTrials.gov Identifier: NCT01038583.
Asunto(s)
Aspirina/uso terapéutico , Trastorno Depresivo Mayor/prevención & control , Anciano , Aspirina/efectos adversos , Trastorno Depresivo Mayor/psicología , Relación Dosis-Respuesta a Droga , Método Doble Ciego , Femenino , Estudios de Seguimiento , Humanos , Masculino , Factores de RiesgoRESUMEN
Binding of mRNA 5' cap by the nuclear cap-binding complex (CBC) is crucial for a wide variety of mRNA metabolic events. The interaction involving the CBP20 subunit of CBC is mediated by numerous hydrogen bonds and by stacking of the tyrosine sidechains with two first bases of the capped mRNA. To examine a possible role of a longer mRNA chain in the CBC-cap recognition, we have synthesized an mRNA tetramer using a novel way of capping an RNA trimer and determined its affinity for CBC by fluorescence titration.
Asunto(s)
Complejo Proteico Nuclear de Unión a la Caperuza/química , Caperuzas de ARN/química , ARN Mensajero/química , Relación Dosis-Respuesta a Droga , Humanos , Cinética , Sustancias Macromoleculares , Modelos Químicos , Conformación de Ácido Nucleico , Unión Proteica , Precursores del ARN , Empalme del ARN , ARN Mensajero/metabolismo , Ribonucleoproteínas/química , Espectrometría de Fluorescencia/métodosRESUMEN
The heterodimeric nuclear cap-binding complex (CBC) specifically recognizes the monomethylguanosine 5' cap structure of the eukaryotic RNA polymerase II transcripts such as mRNA and U snRNA. The binding is essential for nuclear maturation of mRNA, for nuclear export of U snRNA in metazoans, and for nonsense-mediated decay of mRNA and the pioneer round of translation. We analysed the recognition of the cap by native human CBC and mutants in which each tyrosine that stacks with the 7-methylguanosine moiety was replaced by phenylalanine or alanine and both tyrosines were replaced by phenylalanines. The equilibrium association constants (K(as)) for two selected cap analogues, P(1)-7-methylguanosine-5' P(3)-guanosine-5' triphosphate and 7-methylguanosine triphosphate, were determined by two independent methods, fluorescence titration and surface plasmon resonance. We could distinguish two tyrosines, Y43 and Y20, in stabilization of the cap inside the CBC-binding pocket. In particular, lack of Y20 in CBC leads to a greater affinity of the mono- than the dinucleotide cap analogue, in contrast to the wild-type protein. A crucial role of cation-pi stacking in the mechanism of the specific cap recognition by CBC was postulated from the comparison of the experimentally derived Gibbs free binding energy (DeltaG degrees) with the stacking energy (DeltaE) of the 7-methylguanosine/Y binary and ternary complexes calculated by the Møller-Plesset second-order perturbation method. The resulting kinetic model of the association between the capped RNA and CBC, based on the experimental data and quantum calculations, is discussed with respect to the "CBC-to-eukaryotic initiation factor 4E handoff" of mRNA.
Asunto(s)
Complejo Proteico Nuclear de Unión a la Caperuza/metabolismo , Caperuzas de ARN/metabolismo , Tirosina/metabolismo , Sustitución de Aminoácidos/genética , Humanos , Cinética , Modelos Moleculares , Mutagénesis Sitio-Dirigida , Unión Proteica , Estructura Terciaria de Proteína , Resonancia por Plasmón de Superficie , Tirosina/genéticaRESUMEN
MHC-encoded molecules govern adaptive immune responses by presenting peptides to T cell receptors (TCRs). Based on TCR-MHC crystal structures, we revisit the extent of TCR binding degeneracy, a property with important biological consequences because the diversity of TCR ligands that can be encountered exceeds the number of T cell clones present in a person at any one time. We also discuss whether the approximate diagonal binding of TCR on MHC molecules is due to an intrinsic property of the TCR variable regions, or results from the action of the CD4 and CD8 coreceptors during intrathymic T cell selection. Finally, we discuss how MHC restriction of antigen recognition might have emerged during evolution.
Asunto(s)
Presentación de Antígeno/inmunología , Complejo Mayor de Histocompatibilidad/inmunología , Receptores de Antígenos de Linfocitos T/inmunología , Linfocitos T/inmunología , Animales , Antígenos CD4/inmunología , Antígenos CD8/inmunología , HumanosRESUMEN
Binding degeneracy is thought to constitute a fundamental property of the T-cell antigen receptor (TCR), yet its structural basis is poorly understood. We determined the crystal structure of a complex involving the BM3.3 TCR and a peptide (pBM8) bound to the H-2K(bm8) major histocompatibility complex (MHC) molecule, and compared it with the structures of the BM3.3 TCR bound to H-2K(b) molecules loaded with two peptides that had a minimal level of primary sequence identity with pBM8. Our findings provide a refined structural view of the basis of BM3.3 TCR cross-reactivity and a structural explanation for the long-standing paradox that a TCR antigen-binding site can be both specific and degenerate. We also measured the thermodynamic features and biological penalties that incurred during cross-recognition. Our data illustrate the difficulty for a given TCR in adapting to distinct peptide-MHC surfaces while still maintaining affinities that result in functional in vivo responses. Therefore, when induction of protective effector T cells is used as the ultimate criteria for adaptive immunity, TCRs are probably much less degenerate than initially assumed.
Asunto(s)
Antígenos/química , Antígenos/inmunología , Péptidos/química , Receptores de Antígenos de Linfocitos T/inmunología , Secuencia de Aminoácidos , Animales , Regiones Determinantes de Complementariedad/química , Cristalografía por Rayos X , Antígenos H-2/inmunología , Ligandos , Ratones , Modelos Moleculares , Datos de Secuencia Molecular , Proteínas Mutantes/química , Estructura Secundaria de Proteína , Termodinámica , TirosinaRESUMEN
Poly(A)-specific ribonuclease (PARN) is a cap-interacting and poly(A)-specific 3'-exoribonuclease. Here we have investigated how the cap binding complex (CBC) affects human PARN activity. We showed that CBC, via its 80-kDa subunit (CBP80), inhibited PARN, suggesting that CBC can regulate mRNA deadenylation. The CBC-mediated inhibition of PARN was cap-independent, and in keeping with this, the CBP80 subunit alone inhibited PARN. Our data suggested a new function for CBC, identified CBC as a potential regulator of PARN, and emphasized the importance of communication between the two extreme ends of the mRNA as a key strategy to regulate mRNA degradation. Based on our data, we have proposed a model for CBC-mediated regulation of PARN, which relies on an interaction between CBP80 and PARN. Association of CBC with PARN might have importance in the regulated recruitment of PARN to the nonsense-mediated decay pathway during the pioneer round of translation.
Asunto(s)
Exorribonucleasas/antagonistas & inhibidores , Complejo Proteico Nuclear de Unión a la Caperuza/fisiología , ARN Mensajero/metabolismo , Exorribonucleasas/fisiología , Humanos , Poliadenilación , Subunidades de Proteína , Caperuzas de ARN/fisiologíaRESUMEN
We have characterized three different programs of activation for alloreactive CD8 T cells expressing the BM3.3 TCR, their elicitation depending on the characteristics of the stimulating peptide/MHC complex. The high-affinity interaction between the TCR and the K(b)-associated endogenous peptide pBM1 (INFDFNTI) induced a complete differentiation program into effector cells correlated with sustained ERK activation. The K(bm8) variant elicited a partial activation program with delayed T cell proliferation, poor CTL activity and undetectable ERK phosphorylation; this resulted from a low-avidity interaction of TCR BM3.3 with a newly identified endogenous peptide, pBM8 (SQYYYNSL). Interestingly, mismatched pBM1/K(bm8) complexes induced a split response in BM3.3 T cells, with total reconstitution of T cell proliferation but defective generation of CTL activity that was correlated with strong but shortened ERK phosphorylation. Crystal structures highlight the molecular basis for the higher stability of pBM8/K(bm8) compared to pBM1/K(bm8) complexes that exist in two conformers. This study illustrates the importance of the stability of both peptide/MHC and peptide/MHC-TCR interactions for induction of sustained signaling required to induce optimal CTL effector functions. Subtle allelic structural variations, amplified by peptide selection, may thus orient distinct outcomes of alloreactive TCR-based therapies.
Asunto(s)
Linfocitos T CD8-positivos/inmunología , Antígenos H-2/inmunología , Antígenos de Histocompatibilidad/inmunología , Isoantígenos/fisiología , Activación de Linfocitos/inmunología , Péptidos/fisiología , Animales , Linfocitos T CD8-positivos/metabolismo , Células Clonales , Ratones , Ratones Transgénicos , Receptores de Antígenos de Linfocitos T/genéticaRESUMEN
The heterodimeric nuclear cap-binding complex (CBC) binds to the mono-methylated 5' cap of eukaryotic RNA polymerase II transcripts such as mRNA and U snRNA. The binding is important for nuclear maturation of mRNAs and possibly in the first round of translation and nonsense-mediated decay. It is also essential for nuclear export of U snRNAs in metazoans. We report characterization by fluorescence spectroscopy of the recognition of 5' capped RNA by human CBC. The association constants (K(as)) for 17 mono- and dinucleotide cap analogs as well as for the oligomer m7GpppA(m2') pU(m2')pA(m2') cover the range from 1.8 x 10(6) M(-1) to 2.3 x 10(8) M(-1). Higher affinity for CBC is observed for the dinucleotide compared with mononucleotide analogs, especially for those containing a purine nucleoside next to m7G. The mRNA tetramer associates with CBC as tightly as the dinucleotide analogs. Replacement of Tyr138 by alanine in the CBP20 subunit of CBC reduces the cap affinity except for the mononucleotide analogs, consistent with the crystallographic observation of the second base stacking on this residue. Our spectroscopic studies showed that contrary to the other known cap-binding proteins, the first two nucleotides of a capped-RNA are indispensable for its specific recognition by CBC. Differences in the cap binding of CBC compared with the eukaryotic translation initiation factor 4E (eIF4E) are analyzed and discussed regarding replacement of CBC by eIF4E.
Asunto(s)
Complejo Proteico Nuclear de Unión a la Caperuza/metabolismo , Caperuzas de ARN/metabolismo , ARN Mensajero/metabolismo , Sitios de Unión , Humanos , Cinética , Mutagénesis Sitio-Dirigida , Complejo Proteico Nuclear de Unión a la Caperuza/química , Complejo Proteico Nuclear de Unión a la Caperuza/genética , Unión Proteica , Caperuzas de ARN/genética , ARN Mensajero/genética , VolumetríaRESUMEN
The nuclear cap-binding complex (CBC) binds the 7-methyl-G(5')ppp(5')N cap structure at the 5' end of pre-messenger and uracil-rich small nuclear RNAs in the nucleus. It mediates interaction of these capped RNAs with various nuclear machineries involved in RNA maturation and is co-exported with them to the cytoplasm. The structure of human CBC, which comprises the subunits CBP20 and CBP80, has previously been determined in a mildly trypsinated form which can no longer bind the cap. Here, the engineering and crystallization of two variant CBCs with deletions in CBP80 which do not affect function are described. A complex with a small N-terminal deletion in CBP80 was crystallized in space group C2 with one complex per asymmetric unit. The crystals diffract to 2 A resolution and give the first structure of intact but cap-free CBC. An additional internal deletion in CBP80 of a prominent solvent-exposed coiled coil gives rise to a more compact complex. This was co-crystallized with the cap analogue m(7)GpppG in two different crystal forms which could grow in the same drop. Form 1 belongs to space group P3(1)21 with one complex per asymmetric unit and diffracts to 2.15 A resolution. Form 2 belongs to space group P2(1)2(1)2(1) with two complexes per asymmetric unit and diffracts to 2.3 A resolution. In both forms, strong extra electron density is observed for the cap analogue and for the N- and C-terminal extensions of CBP20 which was absent or disordered in all previous structures.
Asunto(s)
Fosfatos de Dinucleósidos/química , Complejo Proteico Nuclear de Unión a la Caperuza , Fosfoproteínas/química , Ingeniería de Proteínas , Caperuzas de ARN/química , Proteínas de Saccharomyces cerevisiae , Secuencia de Bases , Clonación Molecular , Cristalización , Cartilla de ADN , Humanos , Fosfoproteínas/genética , Fosfoproteínas/aislamiento & purificaciónRESUMEN
The heterodimeric nuclear cap-binding complex (CBC) binds to the 5' cap structure of RNAs in the nucleus and plays a central role in their diverse maturation steps. We describe the crystal structure at 2.1 A resolution of human CBC bound to an m(7)GpppG cap analogue. Comparison with the structure of uncomplexed CBC shows that cap binding induces co-operative folding around the dinucleotide of some 50 residues from the N- and C-terminal extensions to the central RNP domain of the small subunit CBP20. The cap-bound conformation of CBP20 is stabilized by an intricate network of interactions both to the ligand and within the subunit, as well as new interactions of the CBP20 N-terminal tail with the large subunit CBP80. Although the structure is very different from that of other known cap-binding proteins, such as the cytoplasmic cap-binding protein eIF4E, specificity for the methylated guanosine again is achieved by sandwiching the base between two aromatic residues, in this case two conserved tyrosines. Implications for the transfer of capped mRNAs to eIF4E, required for translation initiation, are discussed.
Asunto(s)
Fosfatos de Dinucleósidos/química , Fosfatos de Dinucleósidos/metabolismo , Complejo Proteico Nuclear de Unión a la Caperuza/química , Complejo Proteico Nuclear de Unión a la Caperuza/metabolismo , Análogos de Caperuza de ARN/química , Análogos de Caperuza de ARN/metabolismo , Secuencia de Aminoácidos , Animales , Sitios de Unión , Cristalografía por Rayos X , Femenino , Humanos , Técnicas In Vitro , Sustancias Macromoleculares , Modelos Moleculares , Datos de Secuencia Molecular , Estructura Molecular , Complejo Proteico Nuclear de Unión a la Caperuza/genética , Oocitos/metabolismo , Filogenia , Unión Proteica , Conformación Proteica , Pliegue de Proteína , Subunidades de Proteína , Caperuzas de ARN/química , Caperuzas de ARN/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Homología de Secuencia de Aminoácido , XenopusRESUMEN
When the nucleoprotein (N) of nonsegmented negative-strand RNA viruses is expressed in insect cells, it binds to cellular RNA and forms N-RNA complexes just like viral nucleocapsids. However, in virus-infected cells, N is prevented from binding to cellular RNA because a soluble complex is formed between N and the viral phosphoprotein (P), the N degrees -P complex. N is only released from this complex for binding to newly made viral or complementary RNA. We coexpressed rabies virus N and P proteins in insect cells and purified the N degrees -P complex. Characterisation by gel filtration, polyacrylamide gel electrophoresis, analytical ultracentrifugation, native mass spectroscopy, and electron microscopy showed that the complex consists of one N protein plus two P proteins, i.e., an N degrees -P(2) complex.