Insights into the hyperthermostability and unusual region-specificity of archaeal Pyrococcus abyssi tRNA m1A57/58 methyltransferase

The S-adenosyl-l-methionine dependent methylation of adenine 58 in the T-loop of tRNAs is essential for cell growth in yeast or for adaptation to high temperatures in thermophilic organisms. In contrast to bacterial and eukaryotic tRNA m1A58 methyltransferases that are site-specific, the homologous archaeal enzyme from Pyrococcus abyssi catalyzes the formation of m1A also at the adjacent position 57, m1A57 being a precursor of 1-methylinosine. We report here the crystal structure of P. abyssi tRNA m1A57/58 methyltransferase (PabTrmI), in complex with S-adenosyl-l-methionine or S-adenosyl-l-homocysteine in three different space groups. The fold of the monomer and the tetrameric architecture are similar to those of the bacterial enzymes. However, the inter-monomer contacts exhibit unique features. In particular, four disulfide bonds contribute to the hyperthermostability of the archaeal enzyme since their mutation lowers the melting temperature by 16.5°C. His78 in conserved motif X, which is present only in TrmIs from the Thermococcocales order, lies near the active site and displays two alternative conformations. Mutagenesis indicates His78 is important for catalytic efficiency of PabTrmI. When A59 is absent in tRNAAsp, only A57 is modified. Identification of the methylated positions in tRNAAsp by mass spectrometry confirms that PabTrmI methylates the first adenine of an AA sequence

Typical investigational medicinal products follow relatively uniform regulations in 10 European Clinical Research Infrastructures Network (ECRIN) countries

<p>Abstract</p> <p>Background</p> <p>In order to facilitate multinational clinical research, regulatory requirements need to become international and harmonised. The EU introduced the Directive 2001/20/EC in 2004, regulating investigational medicinal products in Europe.</p> <p>Methods</p> <p>We conducted a survey in order to identify the national regulatory requirements for major categories of clinical research in ten European Clinical Research Infrastructures Network (ECRIN) countries-Austria, Denmark, France, Germany, Hungary, Ireland, Italy, Spain, Sweden, and United Kingdom-covering approximately 70% of the EU population. Here we describe the results for regulatory requirements for typical investigational medicinal products, in the ten countries.</p> <p>Results</p> <p>Our results show that the ten countries have fairly harmonised definitions of typical investigational medicinal products. Clinical trials assessing typical investigational medicinal products require authorisation from a national competent authority in each of the countries surveyed. The opinion of the competent authorities is communicated to the trial sponsor within the same timelines, i.e., no more than 60 days, in all ten countries. The authority to which the application has to be sent to in the different countries is not fully harmonised.</p> <p>Conclusion</p> <p>The Directive 2001/20/EC defined the term 'investigational medicinal product' and all regulatory requirements described therein are applicable to investigational medicinal products. Our survey showed, however, that those requirements had been adopted in ten European countries, not for investigational medicinal products overall, but rather a narrower category which we term 'typical' investigational medicinal products. The result is partial EU harmonisation of requirements and a relatively navigable landscape for the sponsor regarding typical investigational medicinal products.</p

Structural comparison of tRNA m¹A58 methyltransferases revealed different molecular strategies to maintain their oligomeric architecture under extreme conditions

<p>Abstract</p> <p>Background</p> <p>tRNA m¹A58 methyltransferases (TrmI) catalyze the transfer of a methyl group from S-adenosyl-L-methionine to nitrogen 1 of adenine 58 in the T-loop of tRNAs from all three domains of life. The m¹A58 modification has been shown to be essential for cell growth in yeast and for adaptation to high temperatures in thermophilic organisms. These enzymes were shown to be active as tetramers. The crystal structures of five TrmIs from hyperthermophilic archaea and thermophilic or mesophilic bacteria have previously been determined, the optimal growth temperature of these organisms ranging from 37°C to 100°C. All TrmIs are assembled as tetramers formed by dimers of tightly assembled dimers.</p> <p>Results</p> <p>In this study, we present a comparative structural analysis of these TrmIs, which highlights factors that allow them to function over a large range of temperature. The monomers of the five enzymes are structurally highly similar, but the inter-monomer contacts differ strongly. Our analysis shows that bacterial enzymes from thermophilic organisms display additional intermolecular ionic interactions across the dimer interfaces, whereas hyperthermophilic enzymes present additional hydrophobic contacts. Moreover, as an alternative to two bidentate ionic interactions that stabilize the tetrameric interface in all other TrmI proteins, the tetramer of the archaeal <it>P. abyssi </it>enzyme is strengthened by four intersubunit disulfide bridges.</p> <p>Conclusions</p> <p>The availability of crystal structures of TrmIs from mesophilic, thermophilic or hyperthermophilic organisms allows a detailed analysis of the architecture of this protein family. Our structural comparisons provide insight into the different molecular strategies used to achieve the tetrameric organization in order to maintain the enzyme activity under extreme conditions.</p

Review on physical and chemical characterizations of contaminated sediments from urban stormwater infiltration basins within the framework of the French observatory for urban hydrology (SOERE URBIS)

International audienceUrban stormwater infiltration basins are designed to hold runoff from impervious surfaces and allow the settling of sediments and associated pollutants. However concerns have been expressed about the environmental impacts that may be exerted by the trapped pollutants on groundwater, soils and ecosystems. In this context, sediment characterization represents a key issue for local authorities in terms of management strategies. During the last two decades, several studies were launched including either physical or chemical characterization of stormwater sediments but without real synthesis of data and methods used. Consequently, there is an important need for reviewing the current experimental techniques devoted to the physico-chemical characterization of sediment. The review is based on the outcomes of two experimental sites for which long term monitoring and data collection have been done: the Chevir, basin (near Nantes) and the Django Reinhardt basin (near Lyon). The authors summarize the studies dealing with bulk properties, pollutant contents, their potential mobility and speciation. This paper aims at promoting the significant progresses that were made through a multidisciplinary approach involving multi-scaled and combined experimental techniques

La viticulture antique en Aquitaine

Le présent bilan est le fruit d'un travail d'équipe qui a été mené entre 1997 et 1999 dans le cadre d'un programme collectif de recherche sur la viticulture antique en Aquitaine, centré à l'origine sur les installations de production reconnues ou supposées dans plusieurs départements au nord et au sud de la Garonne (Charente-Maritime, Charente, Dordogne, Gironde, Lot-et-Garonne, Lot, Gers, Tarn et Haute-Garonne). L'article s'organise en deux parties complémentaires. La première met en évidence les principales sources d'information sur la viticulture en Aquitaine : témoignages littéraires et surtout documentation archéologique fournie par les travaux sur les amphores vinaires et entièrement renouvelée par l'apport des fouilles récentes d'établissements vinicoles (Bapteste, Belmont, Les Chapelles, Lestagnac...). Des exposés synthétiques évoquent ensuite différents aspects de la production du vin, depuis les cépages et les outils jusqu'aux techniques agricoles et à la vinification. Un essai de chronologie clôt l'ensemble de l'étude.The present work is the result of a team effort conducted from 1997 to 1999 in a multidisciplinary program of research dealing with vine growing in Aquitaine. From the outset, this research was focused on known or presumed wine-making facilities in several departments located north and south of the Garonne (Charente-Maritime, Charente, Dordogne, Gironde, Lot-et-Garonne, Lot, Gers, Tarn and Haute-Garonne). The article is divided into two complementary parts. The first treats of the chief sources of information about vine growing in Aquitaine: literary accounts and especially archaeological documentation gained from research on wine amphorae, which has been richly supplemented by recent excavations of wine-making establishments (Bapteste, Belmont, Les Chapelles, Lestagnac...). In addition, interpretative essays discuss assorted aspects of wine production, including varieties of wine and tools, as well as techniques for cultivating and processing wine. A chronological study completes the work

Les Parentalités en Afrique musulmane

L’étude de la famille dans le Nord de l’Afrique, et dans les sociétés musulmanes, a connu ces quinze dernières années des développements fort intéressants en raison des transformations des codes familiaux, ainsi que du déploiement de nouvelles technologies dans le domaine de la reproduction et des questions bioéthiques qui l’accompagnent (Bras, 2007 ; Bonte, Benkheira, 2009-2010 ; Clarke, 2009 ; Fortier, 2010 ; Voorhoeve, 2012 ; Benkheira et al., 2013). Celles-ci traduisent par ailleurs des mutations sociétales importantes et profondes (augmentation de la population urbaine, de l’accès à l’éducation et du travail salarié féminin, notamment) et une relecture des normes islamiques et/ou traditionnelles/coutumières, notamment en matière d’égalité entre hommes et femmes. Toutefois, alors qu’une vaste littérature aborde le sujet des transformations de la famille en Europe et ailleurs, sous l’angle de la parentalité (parenthood) – repenser la famille à partir de l’enfant et de son bien-être –, force est de constater que les travaux dans cette perspective sont rares s’agissant des sociétés du Nord de l’Afrique, et plus largement des sociétés musulmanes. Cet ouvrage constitue donc une contribution à l’étude de la parentalité en Afrique musulmane, avec un focus particulier sur les pays de l’Afrique du Nord. L’objectif, ici, est de renouveler les questionnements, les perspectives et les analyses s’agissant des constances et des transformations des liens familiaux en contexte musulman africain. Les directeurs de la publication souhaitent remercier Sabrina Mervin, l'ancienne directrice du Centre Jacques Berque, pour le soutien apporté au programme à l'origine de cet ouvrage collectif

Typical investigational medicinal products follow relatively uniform regulations in 10 european clinical research infrastructures network (ecrin) countries

Background: In order to facilitate multinational clinical research, regulatory requirements need to become international and harmonised. The EU introduced the Directive 2001/20/EC in 2004, regulating investigational medicinal products in Europe. Methods: We conducted a survey in order to identify the national regulatory requirements for major categories of clinical research in ten European Clinical Research Infrastructures Network (ECRIN) countries-Austria, Denmark, France, Germany, Hungary, Ireland, Italy, Spain, Sweden, and United Kingdom-covering approximately 70% of the EU population. Here we describe the results for regulatory requirements for typical investigational medicinal products, in the ten countries. Results: Our results show that the ten countries have fairly harmonised definitions of typical investigational medicinal products. Clinical trials assessing typical investigational medicinal products require authorisation from a national competent authority in each of the countries surveyed. The opinion of the competent authorities is communicated to the trial sponsor within the same timelines, i.e., no more than 60 days, in all ten countries. The authority to which the application has to be sent to in the different countries is not fully harmonised. Conclusion: The Directive 2001/20/EC defined the term \u27investigational medicinal product\u27 and all regulatory requirements described therein are applicable to investigational medicinal products. Our survey showed, however, that those requirements had been adopted in ten European countries, not for investigational medicinal products overall, but rather a narrower category which we term \u27typical\u27 investigational medicinal products. The result is partial EU harmonisation of requirements and a relatively navigable landscape for the sponsor regarding typical investigational medicinal products