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Position of Eukaryotic Translation Initiation Factor eIF1A on the 40S Ribosomal Subunit Mapped by Directed Hydroxyl Radical Probing
The universally conserved eukaryotic initiation factor (eIF), eIF1A, plays multiple roles throughout initiation: it stimulates eIF2/GTP/Met-tRNA_i^{Met} attachment to 40S ribosomal subunits, scanning, start codon selection and subunit joining. Its bacterial ortholog IF1 consists of an oligonucleotide/oligosaccharide-binding (OB) domain, whereas eIF1A additionally contains a helical subdomain, N-terminal tail (NTT) and C-terminal tail (CTT). The NTT and CTT both enhance ribosomal recruitment of eIF2/GTP/Met-tRNA_i^{Met}, but have opposite effects on the stringency of start codon selection: the CTT increases, whereas the NTT decreases it. Here, we determined the position of eIF1A on the 40S subunit by directed hydroxyl radical cleavage. eIF1A's OB domain binds in the A site, similar to IF1, whereas the helical subdomain contacts the head, forming a bridge over the mRNA channel. The NTT and CTT both thread under Met-tRNA_i^{Met} reaching into the P-site. The NTT threads closer to the mRNA channel. In the proposed model, the NTT does not clash with either mRNA or Met-tRNA_i^{Met}, consistent with its suggested role in promoting the âclosedâ conformation of ribosomal complexes upon start codon recognition. In contrast, eIF1A-CTT appears to interfere with the P-site tRNA-head interaction in the âclosedâ complex and is likely ejected from the P-site upon start codon recognition
Position of eukaryotic translation initiation factor eIF1A on the 40S ribosomal subunit mapped by directed hydroxyl radical probing
The universally conserved eukaryotic initiation factor (eIF), eIF1A, plays multiple roles throughout initiation: it stimulates eIF2/GTP/Met-tRNAiMet attachment to 40S ribosomal subunits, scanning, start codon selection and subunit joining. Its bacterial ortholog IF1 consists of an oligonucleotide/oligosaccharide-binding (OB) domain, whereas eIF1A additionally contains a helical subdomain, N-terminal tail (NTT) and C-terminal tail (CTT). The NTT and CTT both enhance ribosomal recruitment of eIF2/GTP/Met-tRNAiMet, but have opposite effects on the stringency of start codon selection: the CTT increases, whereas the NTT decreases it. Here, we determined the position of eIF1A on the 40S subunit by directed hydroxyl radical cleavage. eIF1A's OB domain binds in the A site, similar to IF1, whereas the helical subdomain contacts the head, forming a bridge over the mRNA channel. The NTT and CTT both thread under Met-tRNAiMet reaching into the P-site. The NTT threads closer to the mRNA channel. In the proposed model, the NTT does not clash with either mRNA or Met-tRNAiMet, consistent with its suggested role in promoting the âclosedâ conformation of ribosomal complexes upon start codon recognition. In contrast, eIF1A-CTT appears to interfere with the P-site tRNA-head interaction in the âclosedâ complex and is likely ejected from the P-site upon start codon recognition
Position of eukaryotic translation initiation factor eIF1A on the 40S ribosomal subunit mapped by directed hydroxyl radical probing
The universally conserved eukaryotic initiation factor (eIF), eIF1A, plays multiple roles throughout initiation: it stimulates eIF2/GTP/Met-tRNAiMet attachment to 40S ribosomal subunits, scanning, start codon selection and subunit joining. Its bacterial ortholog IF1 consists of an oligonucleotide/oligosaccharide-binding (OB) domain, whereas eIF1A additionally contains a helical subdomain, N-terminal tail (NTT) and C-terminal tail (CTT). The NTT and CTT both enhance ribosomal recruitment of eIF2/GTP/Met-tRNAiMet, but have opposite effects on the stringency of start codon selection: the CTT increases, whereas the NTT decreases it. Here, we determined the position of eIF1A on the 40S subunit by directed hydroxyl radical cleavage. eIF1A's OB domain binds in the A site, similar to IF1, whereas the helical subdomain contacts the head, forming a bridge over the mRNA channel. The NTT and CTT both thread under Met-tRNAiMet reaching into the P-site. The NTT threads closer to the mRNA channel. In the proposed model, the NTT does not clash with either mRNA or Met-tRNAiMet, consistent with its suggested role in promoting the âclosedâ conformation of ribosomal complexes upon start codon recognition. In contrast, eIF1A-CTT appears to interfere with the P-site tRNA-head interaction in the âclosedâ complex and is likely ejected from the P-site upon start codon recognition
Low arthroplasty survival after treatment for proximal humerus fracture sequelae: 3,245 shoulder replacements from the Nordic Arthroplasty Register Association
Background and purpose - Proximal humerus fractures (PHF) may result in sequelae indicating arthroplasty. We report cumulative survival rates and reasons for revision after arthroplasty for proximal humerus fracture sequelae (PHFS). Patients and methods - Data were derived from the Nordic Arthroplasty Register Association. The Kaplan-Meier method was used to illustrate survival rates. A scaled Schoenfeld residual plot was used to report the risk of revision for men relative to women in patients who were treated with reverse shoulder arthroplasty (RSA). Revision was defined as removal or exchange of any component or the addition of a glenoid component. Results - 30,190 primary arthroplasties were reported from 2004 to 2016, of which 3,245 were for PHFS. The estimated 1-, 5-, and 10-year cumulative survival rates (95% CI) were 96% (95-97), 90% (89-92), and 86% (83-88) for stemmed hemiarthroplasty and 94% (92-95), 89% (87-91), and 86% (82-90) for RSA with a median time to revision of 18 months (IQR 9-44) and 3 months (IQR 0-17). The risk of revision for men relative to women in patients who were treated with RSA was 3.2 (1.9-5.1) 0-1 year after surgery and 1.9 (0.9-4.1) 1-8 years after surgery. The estimated 1-, 5-, and 10-year cumulative survival rates (95% CI) were 94% (92-96), 88% (85-90), and 80% (75-86) for men and 95% (94-96), 86% (84-89), and 81% (77-84) for young patients. Interpretation - Shoulder arthroplasty for PHFS was associated with lower survival rates, compared with previously published results of shoulder arthroplasty for acute PHF. The low arthroplasty survival rates for men and young patients especially are worrying
Analysis of natural variants of the hepatitis C virus internal ribosome entry site reveals that primary sequence plays a key role in cap-independent translation
The HCV internal ribosome entry site (IRES) spans a region of âŒ340 nt that encompasses most of the 5âČ untranslated region (5âČUTR) of the viral mRNA and the first 24â40 nt of the core-coding region. To investigate the implication of altering the primary sequence of the 5âČUTR on IRES activity, naturally occurring variants of the 5âČUTR were isolated from clinical samples and analyzed. The impact of the identified mutations on translation was evaluated in the context of RLuc/FLuc bicistronic RNAs. Results show that depending on their location within the RNA structure, these naturally occurring mutations cause a range of effects on IRES activity. However, mutations within subdomain IIId hinder HCV IRES-mediated translation. In an attempt to explain these data, the dynamic behavior of the subdomain IIId was analyzed by means of molecular dynamics (MD) simulations. Despite the loss of function, MD simulations predicted that mutant G266A/G268U possesses a structure similar to the wt-RNA. This prediction was validated by analyzing the secondary structure of the isolated IIId RNAs by circular dichroism spectroscopy in the presence or absence of Mg2+ ions. These data strongly suggest that the primary sequence of subdomain IIId plays a key role in HCV IRES-mediated translation
Final Pre-40S Maturation Depends on the Functional Integrity of the 60S Subunit Ribosomal Protein L3
Ribosomal protein L3 is an evolutionarily conserved protein that participates in the assembly of early pre-60S particles. We report that the rpl3[W255C] allele, which affects the affinity and function of translation elongation factors, impairs cytoplasmic maturation of 20S pre-rRNA. This was not seen for other mutations in or depletion of L3 or other 60S ribosomal proteins. Surprisingly, pre-40S particles containing 20S pre-rRNA form translation-competent 80S ribosomes, and translation inhibition partially suppresses 20S pre-rRNA accumulation. The GTP-dependent translation initiation factor Fun12 (yeast eIF5B) shows similar in vivo binding to ribosomal particles from wild-type and rpl3[W255C] cells. However, the GTPase activity of eIF5B failed to stimulate processing of 20S pre-rRNA when assayed with ribosomal particles purified from rpl3[W255C] cells. We conclude that L3 plays an important role in the function of eIF5B in stimulating 3âČ end processing of 18S rRNA in the context of 80S ribosomes that have not yet engaged in translation. These findings indicate that the correct conformation of the GTPase activation region is assessed in a quality control step during maturation of cytoplasmic pre-ribosomal particles
Prospects for combined analyses of hadronic emission from -ray sources in the Milky Way with CTA and KM3NeT
The Cherenkov Telescope Array and the KM3NeT neutrino telescopes are major
upcoming facilities in the fields of -ray and neutrino astronomy,
respectively. Possible simultaneous production of rays and neutrinos
in astrophysical accelerators of cosmic-ray nuclei motivates a combination of
their data. We assess the potential of a combined analysis of CTA and KM3NeT
data to determine the contribution of hadronic emission processes in known
Galactic -ray emitters, comparing this result to the cases of two
separate analyses. In doing so, we demonstrate the capability of Gammapy, an
open-source software package for the analysis of -ray data, to also
process data from neutrino telescopes. For a selection of prototypical
-ray sources within our Galaxy, we obtain models for primary proton and
electron spectra in the hadronic and leptonic emission scenario, respectively,
by fitting published -ray spectra. Using these models and instrument
response functions for both detectors, we employ the Gammapy package to
generate pseudo data sets, where we assume 200 hours of CTA observations and 10
years of KM3NeT detector operation. We then apply a three-dimensional binned
likelihood analysis to these data sets, separately for each instrument and
jointly for both. We find that the largest benefit of the combined analysis
lies in the possibility of a consistent modelling of the -ray and
neutrino emission. Assuming a purely leptonic scenario as input, we obtain, for
the most favourable source, an average expected 68% credible interval that
constrains the contribution of hadronic processes to the observed -ray
emission to below 15%.Comment: 18 pages, 15 figures. Submitted to journa
The KM3NeT potential for the next core-collapse supernova observation with neutrinos
The authors acknowledge the financial support of the funding agencies: Agence Nationale de la Recherche (contract ANR-15-CE31-0020), Centre National de la Recherche Scientifique (CNRS), Commission Europeenne (FEDER fund and Marie Curie Program), Institut Universitaire de France (IUF), LabEx UnivEarthS (ANR-10-LABX-0023 and ANR-18-IDEX-0001), Paris Ile-de-France Region, France; Shota Rustaveli National Science Foundation of Georgia (SRNSFG, FR-18-1268), Georgia; Deutsche Forschungsgemeinschaft (DFG), Germany; The General Secretariat of Research and Technology (GSRT), Greece; Istituto Nazionale di Fisica Nucleare (INFN), Ministero dell'Universita e della Ricerca (MIUR), PRIN 2017 program (Grant NAT-NET 2017W4HA7S) Italy; Ministry of Higher Education Scientific Research and Professional Training, ICTP through Grant AF-13, Morocco; Nederlandse organisatie voor Wetenschappelijk Onderzoek (NWO), the Netherlands; The National Science Centre, Poland (2015/18/E/ST2/00758); National Authority for Scientific Research (ANCS), Romania; Ministerio de Ciencia, Innovacion, Investigacion y Universidades (MCIU): Programa Estatal de Generacion de Conocimiento (refs. PGC2018-096663-B-C41, -A-C42, -B-C43, -B-C44) (MCIU/FEDER), Severo Ochoa Centre of Excellence and MultiDark Consolider (MCIU), Junta de Andalucia (ref. SOMM17/6104/UGR), Generalitat Valenciana: Grisolia (ref. GRISO-LIA/2018/119) and GenT (ref. CIDEGENT/2018/034 and CIDE-GENT/2019/043) programs, La Caixa Foundation (ref. LCF/BQ/IN17/11620019), EU: MSC program (ref. 713673), Spain. This work has also received funding from the European Union'sHorizon 2020 research and innovation program under Grant agreement no 739560.The KM3NeT research infrastructure is under construction in the Mediterranean Sea. It consists of two water Cherenkov neutrino detectors, ARCA and ORCA, aimed at neutrino astrophysics and oscillation research, respectively. Instrumenting a large volume of sea water with similar to 6200 optical modules comprising a total of similar to 200,000 photomultiplier tubes, KM3NeT will achieve sensitivity to similar to 10 MeV neutrinos from Galactic and near-Galactic core-collapse supernovae through the observation of coincident hits in photomultipliers above the background. In this paper, the sensitivity of KM3NeT to a supernova explosion is estimated from detailed analyses of background data from the first KM3NeT detection units and simulations of the neutrino signal. The KM3NeT observational horizon (for a 5 sigma discovery) covers essentially the Milky-Way and for the most optimistic model, extends to the Small Magellanic Cloud (similar to 60 kpc). Detailed studies of the time profile of the neutrino signal allow assessment of the KM3NeT capability to determine the arrival time of the neutrino burst with a few milliseconds precision for sources up to 5-8 kpc away, and detecting the peculiar signature of the standing accretion shock instability if the core-collapse supernova explosion happens closer than 3-5 kpc, depending on the progenitor mass. KM3NeT's capability to measure the neutrino flux spectral parameters is also presented.French National Research Agency (ANR) ANR-15-CE31-0020Centre National de la Recherche Scientifique (CNRS)Commission Europeenne, FranceInstitut Universitaire de France (IUF), FranceLabEx UnivEarthS, France ANR-10-LABX-0023
ANR-18-IDEX-0001Paris Ile-de-France Region, FranceShota Rustaveli National Science Foundation of Georgia (SRNSFG), Georgia FR-18-1268German Research Foundation (DFG)Greek Ministry of Development-GSRTGreek Ministry of Development-GSRTIstituto Nazionale di Fisica Nucleare (INFN)Ministry of Education, Universities and Research (MIUR)PRIN 2017 program, Italy NAT-NET 2017W4HA7SMinistry of Higher Education Scientific Research and Professional Training, ICTP, Morocco AF-13Netherlands Organization for Scientific Research (NWO)Netherlands GovernmentNational Science Centre, Poland 2015/18/E/ST2/00758National Authority for Scientific Research (ANCS), RomaniaMinisterio de Ciencia, Innovacion, Investigacion y Universidades (MCIU): Programa Estatal de Generacion de Conocimiento, Spain PGC2018-096663-B-C41
PGC2018-096663-A-C42
PGC2018-096663-B-C43
PGC2018-096663-B-C44Severo Ochoa Centre of Excellence and MultiDark Consolider (MCIU), SpainJunta de Andalucia
European Commission SOMM17/6104/UGRGeneralitat Valenciana: Grisolia, Spain GRISO-LIA/2018/119
GenT program, Spain CIDEGENT/2018/034
CIDE-GENT/2019/043La Caixa Foundation LCF/BQ/IN17/11620019
EU: MSC program, Spain 713673European Commission 73956
A deep spectromorphological study of the -ray emission surrounding the young massive stellar cluster Westerlund 1
Young massive stellar clusters are extreme environments and potentially
provide the means for efficient particle acceleration. Indeed, they are
increasingly considered as being responsible for a significant fraction of
cosmic rays (CRs) accelerated within the Milky Way. Westerlund 1, the most
massive known young stellar cluster in our Galaxy is a prime candidate for
studying this hypothesis. While the very-high-energy -ray source HESS
J1646-458 has been detected in the vicinity of Westerlund 1 in the past, its
association could not be firmly identified. We aim to identify the physical
processes responsible for the -ray emission around Westerlund 1 and
thus to better understand the role of massive stellar clusters in the
acceleration of Galactic CRs. Using 164 hours of data recorded with the High
Energy Stereoscopic System (H.E.S.S.), we carried out a deep
spectromorphological study of the -ray emission of HESS J1646-458. We
furthermore employed H I and CO observations of the region to infer the
presence of gas that could serve as target material for interactions of
accelerated CRs. We detected large-scale ( diameter) -ray
emission with a complex morphology, exhibiting a shell-like structure and
showing no significant variation with -ray energy. The combined energy
spectrum of the emission extends to several tens of TeV, and is uniform across
the entire source region. We did not find a clear correlation of the
-ray emission with gas clouds as identified through H I and CO
observations. We conclude that, of the known objects within the region, only
Westerlund 1 can explain the bulk of the -ray emission. Several CR
acceleration sites and mechanisms are conceivable, and discussed in detail.
(abridged)Comment: 15 pages, 9 figures. Corresponding authors: L. Mohrmann, S. Ohm, R.
Rauth, A. Specoviu
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