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BACKGROUND: The risk of infection with avian influenza A viruses currently circulating in wild and domestic birds in the Americas is considered low for the general public; however, detections in humans have been reported and warning signs of increased zoonotic potential have been identified. In December 2022, two Canada geese residing on the grounds of an urban hospital in Maine tested positive for influenza A H5N1 clade 2.3.4.4b. AIMS: Given the opportunity for exposure to staff and hospital visitors through potentially infected faeces on the property, public health authorities determined mitigation efforts were needed to prevent the spread of disease. The ensuing response relied on collaboration between the public health and animal health agencies to guide the hospital through efforts in preventing possible zoonotic transmission to humans. MATERIALS AND METHODS: Mitigation efforts included staff communication and education, environmental cleaning and disinfection, enhanced illness surveillance among staff and patients, and exposure and source reduction. RESULTS: No human H5N1 cases were identified, and no additional detections in birds on the property occurred. Hospital staff identified barriers to preparedness resulting from a lack of understanding of avian influenza A viruses and transmission prevention methods, including avian influenza risk in resident wild bird populations and proper wildlife management methods. CONCLUSION: As this virus continues to circulate at the animal-human interface, this event and resulting response highlights the need for influenza A H5N1 risk awareness and guidance for facilities and groups not traditionally involved in avian influenza responses.
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Subtipo H5N1 del Virus de la Influenza A , Virus de la Influenza A , Gripe Aviar , Gripe Humana , Humanos , Animales , Gripe Aviar/epidemiología , Gripe Aviar/prevención & control , Gripe Humana/epidemiología , Gripe Humana/prevención & control , Maine/epidemiología , Aves , Animales Salvajes , Hospitales , FilogeniaRESUMEN
N-carbamoyl-ß-alanine amidohydrolase (CßAA) constitutes one of the most important groups of industrially relevant enzymes used in the production of optically pure amino acids and derivatives. In this study, a CßAA-encoding gene from Rhizobium radiobacter strain MDC 8606 was cloned and overexpressed in Escherichia coli. The purified recombinant enzyme (RrCßAA) showed a specific activity of 14 U·mg-1 using N-carbamoyl-ß-alanine as a substrate with an optimum activity at 55 °C and pH 8.0. In this work, we report also the first prokaryotic CßAA structure at a resolution of 2.0 Å. A discontinuous catalytic domain and a dimerisation domain attached through a flexible hinge region at the domain interface have been revealed. We identify key ligand binding residues, including a conserved glutamic acid (Glu131), histidine (H385) and arginine (Arg291). Our results allowed us to explain the preference of the enzyme for linear carbamoyl substrates, as large and branched carbamoyl substrates cannot fit in the active site of the enzyme. This work envisages the use of RrCßAA from R. radiobacter MDC 8606 for the industrial production of L-α-, L-ß- and L-γ-amino acids. The structural analysis provides new insights on enzyme-substrate interaction, which shed light on engineering of CßAAs for high catalytic activity and broad substrate specificity.
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Agrobacterium tumefaciens , Aminoácidos , Agrobacterium tumefaciens/genética , Agrobacterium tumefaciens/metabolismo , beta-Alanina , Amidohidrolasas/genética , Amidohidrolasas/metabolismo , Especificidad por SustratoRESUMEN
OBJECTIVES: Early in the COVID-19 pandemic, several outbreaks were linked with facilities employing essential workers, such as long-term care facilities and meat and poultry processing facilities. However, timely national data on which workplace settings were experiencing COVID-19 outbreaks were unavailable through routine surveillance systems. We estimated the number of US workplace outbreaks of COVID-19 and identified the types of workplace settings in which they occurred during August-October 2021. METHODS: The Centers for Disease Control and Prevention collected data from health departments on workplace COVID-19 outbreaks from August through October 2021: the number of workplace outbreaks, by workplace setting, and the total number of cases among workers linked to these outbreaks. Health departments also reported the number of workplaces they assisted for outbreak response, COVID-19 testing, vaccine distribution, or consultation on mitigation strategies. RESULTS: Twenty-three health departments reported a total of 12 660 workplace COVID-19 outbreaks. Among the 12 470 workplace types that were documented, 35.9% (n = 4474) of outbreaks occurred in health care settings, 33.4% (n = 4170) in educational settings, and 30.7% (n = 3826) in other work settings, including non-food manufacturing, correctional facilities, social services, retail trade, and food and beverage stores. Eleven health departments that reported 3859 workplace outbreaks provided information about workplace assistance: 3090 (80.1%) instances of assistance involved consultation on COVID-19 mitigation strategies, 1912 (49.5%) involved outbreak response, 436 (11.3%) involved COVID-19 testing, and 185 (4.8%) involved COVID-19 vaccine distribution. CONCLUSIONS: These findings underscore the continued impact of COVID-19 among workers, the potential for work-related transmission, and the need to apply layered prevention strategies recommended by public health officials.
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COVID-19 , Humanos , COVID-19/epidemiología , Pandemias/prevención & control , Prueba de COVID-19 , Vacunas contra la COVID-19 , Lugar de Trabajo , Brotes de EnfermedadesRESUMEN
During July 2021, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) B.1.617.2 variant infections, including vaccine breakthrough infections, occurred after large public gatherings in Provincetown, Massachusetts, USA, prompting a multistate investigation. Public health departments identified primary and secondary cases by using coronavirus disease surveillance data, case investigations, and contact tracing. A primary case was defined as SARS-CoV-2 detected <14 days after travel to or residence in Provincetown during July 3-17. A secondary case was defined as SARS-CoV-2 detected <14 days after close contact with a person who had a primary case but without travel to or residence in Provincetown during July 3-August 10. We identified 1,098 primary cases and 30 secondary cases associated with 26 primary cases among fully and non-fully vaccinated persons. Large gatherings can have widespread effects on SARS-CoV-2 transmission, and fully vaccinated persons should take precautions, such as masking, to prevent SARS-CoV-2 transmission, particularly during substantial or high transmission.
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COVID-19 , Vacunas contra la COVID-19 , Brotes de Enfermedades , Humanos , Massachusetts , SARS-CoV-2 , Estados Unidos/epidemiologíaRESUMEN
We describe coronavirus disease (COVID-19) among US food manufacturing and agriculture workers and provide updated information on meat and poultry processing workers. Among 742 food and agriculture workplaces in 30 states, 8,978 workers had confirmed COVID-19; 55 workers died. Racial and ethnic minority workers could be disproportionately affected by COVID-19.
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Agricultura , COVID-19/epidemiología , COVID-19/transmisión , Industria de Alimentos , SARS-CoV-2 , Adulto , Anciano , Femenino , Humanos , Masculino , Persona de Mediana Edad , Estados Unidos/epidemiología , Adulto JovenRESUMEN
SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), is spread from person to person (1-3). Quarantine of exposed persons (contacts) for 14 days following their exposure reduces transmission (4-7). Contact tracing provides an opportunity to identify contacts, inform them of quarantine recommendations, and monitor their symptoms to promptly identify secondary COVID-19 cases (7,8). On March 12, 2020, Maine Center for Disease Control and Prevention (Maine CDC) identified the first case of COVID-19 in the state. Because of resource constraints, including staffing, Maine CDC could not consistently monitor contacts, and automated technological solutions for monitoring contacts were explored. On May 14, 2020, Maine CDC began enrolling contacts of patients with reported COVID-19 into Sara Alert (MITRE Corporation, 2020),* an automated, web-based, symptom monitoring tool. After initial communication with Maine CDC staff members, enrolled contacts automatically received daily symptom questionnaires via their choice of e-mailed weblink, text message, texted weblink, or telephone call until completion of their quarantine. Epidemiologic investigations were conducted for enrollees who reported symptoms or received a positive SARS-CoV-2 test result. During May 14-June 26, Maine CDC enrolled 1,622 contacts of 614 COVID-19 patients; 190 (11.7%) eventually developed COVID-19, highlighting the importance of identifying, quarantining, and monitoring contacts of COVID-19 patients to limit spread. In Maine, symptom monitoring was not feasible without the use of an automated symptom monitoring tool. Using a tool that permitted enrollees to specify a method of symptom monitoring was well received, because the majority of persons monitored (96.4%) agreed to report using this system.
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Trazado de Contacto , Infecciones por Coronavirus/diagnóstico , Infecciones por Coronavirus/terapia , Monitoreo Epidemiológico , Neumonía Viral/diagnóstico , Neumonía Viral/terapia , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Automatización , COVID-19 , Niño , Preescolar , Infecciones por Coronavirus/epidemiología , Infecciones por Coronavirus/prevención & control , Femenino , Humanos , Lactante , Recién Nacido , Maine/epidemiología , Masculino , Persona de Mediana Edad , Pandemias/prevención & control , Neumonía Viral/epidemiología , Neumonía Viral/prevención & control , Evaluación de Programas y Proyectos de Salud , Evaluación de Síntomas/métodos , Adulto JovenRESUMEN
During January 1, 2020-May 18, 2020, approximately 1.3 million cases of coronavirus disease 2019 (COVID-19) and 83,000 COVID-19-associated deaths were reported in the United States (1). Understanding the demographic and clinical characteristics of decedents could inform medical and public health interventions focused on preventing COVID-19-associated mortality. This report describes decedents with laboratory-confirmed infection with SARS-CoV-2, the virus that causes COVID-19, using data from 1) the standardized CDC case-report form (case-based surveillance) (https://www.cdc.gov/coronavirus/2019-ncov/php/reporting-pui.html) and 2) supplementary data (supplemental surveillance), such as underlying medical conditions and location of death, obtained through collaboration between CDC and 16 public health jurisdictions (15 states and New York City).
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Infecciones por Coronavirus/mortalidad , Disparidades en el Estado de Salud , Neumonía Viral/mortalidad , Vigilancia en Salud Pública , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , COVID-19 , Enfermedad Crónica , Infecciones por Coronavirus/etnología , Etnicidad/estadística & datos numéricos , Femenino , Humanos , Masculino , Persona de Mediana Edad , Pandemias , Neumonía Viral/etnología , Grupos Raciales/estadística & datos numéricos , Factores de Riesgo , Estados Unidos/epidemiología , Adulto JovenRESUMEN
Meat and poultry processing facilities face distinctive challenges in the control of infectious diseases, including coronavirus disease 2019 (COVID-19) (1). COVID-19 outbreaks among meat and poultry processing facility workers can rapidly affect large numbers of persons. Assessment of COVID-19 cases among workers in 115 meat and poultry processing facilities through April 27, 2020, documented 4,913 cases and 20 deaths reported by 19 states (1). This report provides updated aggregate data from states regarding the number of meat and poultry processing facilities affected by COVID-19, the number and demographic characteristics of affected workers, and the number of COVID-19-associated deaths among workers, as well as descriptions of interventions and prevention efforts at these facilities. Aggregate data on confirmed COVID-19 cases and deaths among workers identified and reported through May 31, 2020, were obtained from 239 affected facilities (those with a laboratory-confirmed COVID-19 case in one or more workers) in 23 states.* COVID-19 was confirmed in 16,233 workers, including 86 COVID-19-related deaths. Among 14 states reporting the total number of workers in affected meat and poultry processing facilities (112,616), COVID-19 was diagnosed in 9.1% of workers. Among 9,919 (61%) cases in 21 states with reported race/ethnicity, 87% occurred among racial and ethnic minority workers. Commonly reported interventions and prevention efforts at facilities included implementing worker temperature or symptom screening and COVID-19 education, mandating face coverings, adding hand hygiene stations, and adding physical barriers between workers. Targeted workplace interventions and prevention efforts that are appropriately tailored to the groups most affected by COVID-19 are critical to reducing both COVID-19-associated occupational risk and health disparities among vulnerable populations. Implementation of these interventions and prevention efforts across meat and poultry processing facilities nationally could help protect workers in this critical infrastructure industry.
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Infecciones por Coronavirus/epidemiología , Brotes de Enfermedades , Industria de Procesamiento de Alimentos , Enfermedades Profesionales/epidemiología , Neumonía Viral/epidemiología , Adulto , Animales , COVID-19 , Femenino , Humanos , Masculino , Carne , Persona de Mediana Edad , Pandemias , Aves de Corral , Estados Unidos/epidemiologíaRESUMEN
BACKGROUND: Chronic otitis media (COM) is characterized by middle ear fluid predominantly containing cytokines, Nontypeable haemophilus influenzae (NTHi), the mucin MUC5B, and neutrophil extracellular traps (NETs). NETs consist of extracellular DNA coated with antibacterial proteins such as myeloperoxidase (MPO) and citrullinated histone 3 (CitH3). NETs can damage tissues and sustain inflammation. Our study aimed to develop an in vitro model of NETosis, testing COM inductors. METHODS: NETosis was evaluated in fresh blood human neutrophils attached to collagen-coated plates and in suspension exposed to phorbol myristate acetate (PMA) as a control, and COM relevant mediators. Confocal microscopy, DNA fluorescence assay and flow cytometry were used to quantify NETosis. RESULTS: PMA exposure induced DNA, MPO, and CitH3 by immunofluorescence (IF) most significantly at 3 hours (3.8-fold for DAPI, 7.6-fold for MPO, and 6.9-fold for CitH3, all P < .05). IL-8 and TNF-α cytokines showed milder increases of DAPI, MPO, and CitH3 positive cells. NTHi had no effect on these NETs markers. Purified salivary MUC5B (10 to 40 µg/mL) produced potent increases, comparable to PMA. A composite NET score summing the fold-increases for DAPI, MPO, and CitH3 demonstrated PMA at 13.6 to 19 relative to control set at 1; and MUC5B at 8.6 to 16.3 (all P < .05). IL-8 and TNF-α showed scores of 5.4 and 3, respectively, but these were not statistically significant. CONCLUSION: We developed a reliable in vitro assay for NETosis which demonstrated that salivary MUC5B is a potent inductor of NETs whereas IL-8, TNF-α, live and lyzed NTHi demonstrated minimal to no NETosis. LEVEL OF EVIDENCE: NA.
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OBJECTIVES: Otitis media (OM) is a ubiquitous pediatric disease leading to a significant health care burden. There is no medication beneficial to resolving COM fluid, highlighting the need for research in the field. Crucially, current human middle ear epithelial cell models are transformed cells not recapitulating physiological functions. Herein, we describe a new method to proliferate and differentiate pediatric primary middle ear epithelial cells (pMEEC) from patients as a physiological model for the study of OM. METHODS: We adapted a cell reprogramming protocol using irradiated fibroblast feeder medium in addition to Rho kinase inhibitor to proliferate pMEEC collected during cochlear implant surgery. Cells were plated on transwell membranes, proliferated with conditionally reprogrammed culture medium, and transferred to air-liquid interface (ALI). Cultures were maintained for 4 weeks at ALI, photos were taken and cell lysates and secretions were collected over time for characterization analysis using quantitative polymerase chain reaction, Western bolt, and proteomics. Keratins, MUC5B and MUC5AC mucins, and beta tubulin (TUBB) were analyzed at the mRNA and protein level. RESULTS: Cultures took a mean of 2 weeks to proliferate before transwell plating and forming a tight epithelium at ALI from 2 to 4 weeks. Although mRNA expression of MUC5B, MUC5AC, TUBB, and keratin 5 (KRT5) were variable depending on the differentiation stage and the patient, both TUBB and KRT5 proteins were detected until week 2. CONCLUSION: We demonstrate a novel method to proliferate and differentiate pMEECs that express epithelial markers and that are able to secrete mucins for the study of OM. LEVEL OF EVIDENCE: NA.
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BACKGROUND: Lymphatic filariasis (LF) and podoconiosis are disabling diseases, endemic in Ethiopia. The main clinical manifestations include lymphoedema from LF and podoconiosis, and hydrocoele from LF. To ensure access to morbidity management and disability prevention (MMDP) services, data on patient numbers in each implementation unit (IU) is required. House-to-house census is considered the gold standard for determining patient numbers, and data are usually collated and reported using paper-based methods. However, often there are delays in data reaching the regional and central level, which leads to subsequent delays in rolling out and prioritising MMDP services. The increase in mobile phone mHealth tools offers an alternative, potentially more rapid and cost-effective approach. METHODS: As part of an LF and podoconiosis burden assessment conducted in Hawella Tula and Bensa districts in Ethiopia, this study compared the standard paper-based methods with the new MeasureSMS-Morbidity tool for clinical cases data collation and reporting. Health extension workers (HEWs) were trained on both methods. Comparisons were made on patient information; age, gender, location (i.e., kebele), condition, severity of condition and acute attacks. Data were analysed for trends, including the differences in ranking the villages in each district based on the highest to lowest number of cases. In addition, financial and human resource requirements were compared. RESULTS: In total, 59 HEWs (19 from Hawella Tula; 40 from Bensa) collated and reported a similar number of cases by paper-based (n=2,377) and SMS (n=2,372) methods. Significant correlations were found between the two methods for all cases and lymphoedema cases in both districts, and for hydrocoele cases in Bensa district only. The total cost of paper-based reporting was 13.7% more expensive than SMS reporting due to costs associated with data collection and entry. CONCLUSIONS: The rank correlation showed the same villages would be prioritised for delivery of MMDP services, with time and cost-savings observed using SMS reporting, suggesting it is an effective and efficient alternative tool to help facilitate care to those who need it most.
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Nontypeable Haemophilus influenzae (NTHi), one of the most common acute otitis media (OM) pathogens, is postulated to promote middle-ear epithelial remodeling in the progression of OM from acute to chronic. The goal of this study was to examine early quantitative proteomic secretome effects of NTHi lysate exposure in a human middle-ear epithelial cell (HMEEC) line. NTHi lysates were used to stimulate HMEEC, and conditional quantitative stable isotope labeling with amino acids in cell culture of cell secretions was performed. Mass spectrometry analysis identified 766 proteins across samples. Of interest, several heterogeneous nuclear ribonucleoproteins (hnRNPs) were regulated by NTHi lysate treatment, especially hnRNP A2B1 and hnRNP Q, known to be implicated in microRNA (miRNA) packaging in exosomes. After purification, the presence of exosomes in HMEEC secretions was characterized by dynamic light scattering (<100 nm), transmission electron microscopy, and CD63/heat shock protein 70 positivity. hnRNP A2B1 and hnRNP Q were confirmed to be found in exosomes by Western blot and proteomic analysis. Finally, exosomal miRNA content comprised 110 unique miRNAs, with 5 found to be statistically induced by NTHi lysate (miR-378a-3p + miR-378i, miR-200a-3p, miR-378g, miR30d-5p, and miR-222-3p), all known to target innate immunity genes. This study demonstrates that NTHi lysates promote release of miRNA-laden exosomes from middle-ear epithelium in vitro. -Val, S., Krueger, A., Poley, M., Cohen, A., Brown, K., Panigrahi, A., Preciado, D. Nontypeable Haemophilus influenzae lysates increase heterogeneous nuclear ribonucleoprotein secretion and exosome release in human middle-ear epithelial cells.
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Oído Medio/citología , Células Epiteliales/metabolismo , Exosomas/metabolismo , Haemophilus influenzae/patogenicidad , Ribonucleoproteínas/metabolismo , Extractos Celulares/farmacología , Línea Celular , Células Epiteliales/efectos de los fármacos , Células Epiteliales/microbiología , Exocitosis , Haemophilus influenzae/química , Humanos , MicroARNs/genética , MicroARNs/metabolismoRESUMEN
BACKGROUND: Otitis media (OM) is characterized by acute infection progressing to chronic middle ear effusion (MEE). Extracellular secretion of microRNAs (miRNAs) in exosomes is a newly discovered mechanism for cells exerting distant cell genetic regulation. Whether MEE contains exosomes with specific miRNAs is unknown. This study aimed to purify and characterize the exosomal and miRNA content of MEE. METHOD: MEEs were subjected to Exoquick exosomal purification and EXOCET exosomal quantification. Extracted vesicles were analyzed by dynamic light scattering (DLS), transmission electron microscopy (TEM), and immunoblotting of HSP-70. NanoString hybridization was performed to profile miRNAs. Exosomal protein content was profiled by Liquid chromatography tandem mass spectrometry (LC-MS/MS). RESULTS: EXOCET assays showed presence of exosomes (0-0.5 × 107/ml) in MEEs. DLS confirmed exosomal size between 10 and 200 nm. Western blot analysis showed presence of HSP-70. Twenty-nine miRNAs were found to be unique to MEEs. The most abundant miRNA was miR-223, a miRNA typically secreted by neutrophils. Proteomics demonstrated typical neutrophil markers as well as common innate immune molecules. CONCLUSION: To our knowledge, this the first report demonstrating the presence of exosomes transporting miRNAs in MEEs. These findings open a broad and novel area of research in OM pathophysiology as driven by miRNA cell communication.
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Exosomas/metabolismo , MicroARNs/aislamiento & purificación , Otitis Media/metabolismo , Western Blotting , Cromatografía Liquida , Exosomas/ultraestructura , Humanos , Espectrometría de Masas , MicroARNs/metabolismo , Microscopía Electrónica de Transmisión , Otitis Media/fisiopatología , Reacción en Cadena de la Polimerasa , ProteómicaRESUMEN
BACKGROUND: Acute otitis media, an infection of the middle ear, can become chronic after multiple episodes. Microbial influence on chronic otitis media remains unclear. It has been reported that mucin glycoproteins are required for middle ear immune defense against pathogens. We aim to characterize the middle ear effusion (MEE) microbiome using high-throughput sequencing and assess potential associations in microbiome diversity with the presence of the secretory mucins MUC5B and MUC5AC. We hypothesize that MEEs containing MUC5B will exhibit a microbiome largely devoid of typical acute otitis media bacteria. METHODS: Fifty-five MEEs from children undergoing myringotomy at Children's National Health System were recovered. Mucin was semiquantitatively determined through Western blot analysis. DNA was subjected to 16S rRNA amplicon sequencing using the Illumina MiSeq platform. Raw data were processed in mothur (SILVA reference database). Alpha- and beta-diversity metrics were determined. Abundance differences between sample groups were estimated. RESULTS: MUC5B was present in 94.5% and MUC5AC in 65.5% of MEEs. Sequencing revealed 39 genera with a relative abundance ≥0.1%. Haemophilus (22.54%), Moraxella (11.11%) and Turicella (7.84%) were the most abundant. Turicella and Pseudomonas proportions were greater in patients older than 24 months of age. In patients with hearing loss, Haemophilus was more abundant, while Turicella and Actinobacteria were less abundant. Haemophilus was also more abundant in samples containing both secretory mucins. CONCLUSIONS: The microbiome of MEEs from children with chronic otitis media differs according to specific clinical features, such as mucin content, age and presence of hearing loss. These associations provide novel pathophysiologic insights across the spectrum of otitis media progression.
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Microbiota/genética , Mucina 5B/análisis , Otitis Media con Derrame/epidemiología , Otitis Media con Derrame/microbiología , Adolescente , Niño , Preescolar , Estudios de Cohortes , Oído Medio/microbiología , Humanos , Lactante , Mucina 5B/metabolismo , ARN Ribosómico 16S/genéticaRESUMEN
The tRNA m(1)A58 methyltransferase is composed of two subunits encoded by the essential genes TRM6 and TRM61 (formerly GCD10 and GCD14). The trm6-504 mutation results in a defective m(1)A methyltransferase (Mtase) and a temperature-sensitive growth phenotype that is attributable to the absence of m(1)A58 and consequential tRNA(i)(Met) instability. We used a genetic approach to identify the genes responsible for tRNA(i)(Met) degradation in trm6 cells. Three recessive extragenic mutations that suppress trm6-504 mutant phenotypes and restore hypomodified tRNA(i)(Met) to near normal levels were identified. The wild-type allele of one suppressor, DIS3/RRP44, encodes a 3'-5' exoribonuclease and a member of the multisubunit exosome complex. We provide evidence that a functional nuclear exosome is required for the degradation of tRNA(i)(Met) lacking m(1)A58. A second suppressor gene encodes Trf4p, a DNA polymerase (pol sigma) with poly(A) polymerase activity. Whereas deletion of TRF4 leads to stabilization of tRNA(i)(Met), overexpression of Trf4p destabilizes the hypomodified tRNA(i)(Met) in trm6 cells. The hypomodified, but not wild-type, pre-tRNA(i)(Met) accumulates as a polyadenylated species, whose abundance and length distribution both increase upon Trf4p overexpression. These data indicate that a tRNA surveillance pathway exists in yeast that requires Trf4p and the exosome for polyadenylation and degradation of hypomodified pre-tRNA(i)(Met).
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Núcleo Celular/metabolismo , ARN de Transferencia de Metionina/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Núcleo Celular/genética , ADN Polimerasa Dirigida por ADN/genética , ADN Polimerasa Dirigida por ADN/metabolismo , Factor 3 de Iniciación Eucariótica/genética , Factor 3 de Iniciación Eucariótica/metabolismo , Exorribonucleasas/genética , Exorribonucleasas/metabolismo , Complejo Multienzimático de Ribonucleasas del Exosoma , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Regulación Fúngica de la Expresión Génica , Genes Supresores , Mutación , Poliadenilación , Precursores del ARN/metabolismo , Procesamiento Postranscripcional del ARN , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , ARNt Metiltransferasas/genética , ARNt Metiltransferasas/metabolismoRESUMEN
Transcriptional activators interact with multisubunit coactivators that modify chromatin structure or recruit the general transcriptional machinery to their target genes. Budding yeast cells respond to amino acid starvation by inducing an activator of amino acid biosynthetic genes, Gcn4p. We conducted a comprehensive analysis of viable mutants affecting known coactivator subunits from the Saccharomyces Genome Deletion Project for defects in activation by Gcn4p in vivo. The results confirm previous findings that Gcn4p requires SAGA, SWI/SNF, and SRB mediator (SRB/MED) and identify key nonessential subunits of these complexes required for activation. Among the numerous histone acetyltransferases examined, only that present in SAGA, Gcn5p, was required by Gcn4p. We also uncovered a dependence on CCR4-NOT, RSC, and the Paf1 complex. In vitro binding experiments suggest that the Gcn4p activation domain interacts specifically with CCR4-NOT and RSC in addition to SAGA, SWI/SNF, and SRB/MED. Chromatin immunoprecipitation experiments show that Mbf1p, SAGA, SWI/SNF, SRB/MED, RSC, CCR4-NOT, and the Paf1 complex all are recruited by Gcn4p to one of its target genes (ARG1) in vivo. We observed considerable differences in coactivator requirements among several Gcn4p-dependent promoters; thus, only a subset of the array of coactivators that can be recruited by Gcn4p is required at a given target gene in vivo.