Quinternet M.,University of Lorraine |
Rothe B.,University of Lorraine |
Rothe B.,Ecole Polytechnique Federale de Lausanne |
Barbier M.,University of Lorraine |
And 13 more authors.
Journal of Molecular Biology | Year: 2015
In eukaryotes, nucleotide post-transcriptional modifications in RNAs play an essential role in cell proliferation by contributing to pre-ribosomal RNA processing, ribosome assembly and activity. Box C/D small nucleolar ribonucleoparticles catalyze site-specific 2′-O-methylation of riboses, one of the most prevalent RNA modifications. They contain one guide RNA and four core proteins and their in vivo assembly requires numerous factors including (HUMAN/Yeast) BCD1/Bcd1p, NUFIP1/Rsa1p, ZNHIT3/Hit1p, the R2TP complex composed of protein PIH1D1/Pih1p and RPAP3/Tah1p that bridges the R2TP complex to the HSP90/Hsp82 chaperone and two AAA + ATPases. We show that Tah1p can stabilize Pih1p in the absence of Hsp82 activity during the stationary phase of growth and consequently that the Tah1p:Pih1p interaction is sufficient for Pih1p stability. This prompted us to establish the solution structure of the Tah1p:Pih1p complex by NMR. The C-terminal tail S93-S111 of Tah1p snakes along Pih1p264-344 folded in a CS domain to form two intermolecular β-sheets and one covering loop. However, a thorough inspection of the NMR and crystal structures revealed structural differences that may be of functional importance. In addition, our NMR and isothermal titration calorimetry data revealed the formation of direct contacts between Pih1p257-344 and the Hsp82MC domain in the presence of Tah1p. By co-expression in Escherichia coli, we demonstrate that Pih1p has two other direct partners, the Rsa1p assembly factor and the Nop58p core protein, and in vivo and in vitro experiments mapped the required binding domains. Our data suggest that these two interactions are mutually exclusive. The implication of this finding for box C/D small nucleolar ribonucleoparticle assembly is discussed. © 2015 Elsevier Ltd. All rights reserved.
Moreau V.,French Institute of Health and Medical Research |
Moreau V.,University of Bordeaux 1 |
Cordelieres F.P.,University of Bordeaux 1 |
Cordelieres F.P.,French Institute of Health and Medical Research |
And 7 more authors.
Journal of Cell Science | Year: 2015
Every two years, the French Society for Cell Biology (SBCF) organises an international meeting called 'Imaging the Cell'. This year, the 8th edition was held on 24-26 June 2015 at University of Bordeaux Campus Victoire in the city of Bordeaux, France, a UNESCO World Heritage site. Over the course of three days, the meeting provided a forum for experts in different areas of cell imaging. Its unique approach was to combine conventional oral presentations during morning sessions with practical workshops at hosting institutes and the Bordeaux Imaging Center during the afternoons. The meeting, co-organised by Violaine Moreau and Frédéric Saltel (both INSERM U1053, Bordeaux, France), Christel Poujol and Fabrice Cordelières (both Bordeaux Imaging Center, Bordeaux, France) and Isabelle Sagot (Institut de Biochimie et Génétique Cellulaires, Bordeaux, France), brought together about 120 scientists including 16 outstanding speakers to discuss the latest advances in cell imaging. Thanks to recent progress in imaging technologies, cell biologists are now able to visualise, follow and manipulate cellular processes with unprecedented accuracy. The meeting sessions and workshops highlighted some of the most exciting developments in the field, with sessions dedicated to optogenetics, high-content screening, in vivo and live-cell imaging, correlative light and electron microscopy, as well as super-resolution imaging. © 2015.
Saliou J.-M.,University of Strasbourg |
Saliou J.-M.,CNRS Hubert Curien Multi-disciplinary Institute |
Saliou J.-M.,University of Lille Nord de France |
Manival X.,University of Lorraine |
And 11 more authors.
Proteomics | Year: 2015
Site-specific isomerization of uridines into pseudouridines in RNAs is catalyzed either by stand-alone enzymes or by box H/ACA ribonucleoprotein particles (sno/sRNPs). The archaeal box H/ACA sRNPs are five-component complexes that consist of a guide RNA and the aCBF5, aNOP10, L7Ae, and aGAR1 proteins. In this study, we performed pairwise incubations of individual constituents of archaeal box H/ACA sRNPs and analyzed their interactions by native MS to build a 2D-connectivity map of direct binders. We describe the use of native MS in combination with ion mobility-MS to monitor the in vitro assembly of the active H/ACA sRNP particle. Real-time native MS was used to monitor how box H/ACA particle functions in multiple-turnover conditions. Native MS also unambiguously revealed that a substrate RNA containing 5-fluorouridine (f5U) was hydrolyzed into 5-fluoro-6-hydroxy-pseudouridine (f5ho6Ψ). In terms of enzymatic mechanism, box H/ACA sRNP was shown to catalyze the pseudouridylation of a first RNA substrate, then to release the RNA product (S22f5ho6ψ) from the RNP enzyme and reload a new substrate RNA molecule. Altogether, our native MS-based approaches provide relevant new information about the potential assembly process and catalytic mechanism of box H/ACA RNPs. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Lebaudy A.,CNRS Biochemistry and Plant Molecular Physiology Laboratory |
Lebaudy A.,Institute Of Biochimie Et Genetique Cellulaires |
Pascaud F.,CNRS Biochemistry and Plant Molecular Physiology Laboratory |
Very A.-A.,CNRS Biochemistry and Plant Molecular Physiology Laboratory |
And 4 more authors.
Journal of Biological Chemistry | Year: 2010
Guard cells adjust their volume by changing their ion content due to intense fluxes that, for K+, are believed to flow through inward or outward Shaker channels. Because Shaker channels can be homo- or heterotetramers and Arabidopsis guard cells express at least five genes encoding inward Shaker subunits, including the two major ones, KAT1 and KAT2, the molecular identity of inward Shaker channels operating therein is not yet completely elucidated. Here, we first addressed the properties of KAT1-KAT2 heteromers by expressing KAT1-KAT2 tandems in Xenopus oocytes. Then, computer analyses of the data suggested that coexpression of free KAT1 and KAT2 subunits resulted mainly in heteromeric channels made of two subunits of each type due to some preferential association of KAT1-KAT2 heterodimers at the first step of channel assembly. This was further supported by the analysis of KAT2 effect on KAT1 targeting in tobacco cells. Finally, patch-clamp recordings of native inward channels in wild-type and mutant genotypes strongly suggested that this preferential heteromerization occurs in planta and that Arabidopsis guard cell inward Shaker channels are mainly heteromers of KAT1 and KAT2 subunits. © 2010 by The American Society for Biochemistry and Molecular Biology, Inc.
Deletion of the uracil permease gene confers cross-resistance to 5-fluorouracil and azoles in Candida lusitaniae and highlights antagonistic interaction between fluorinated nucleotides and fluconazole
Gabriel F.,University of Bordeaux 1 |
Gabriel F.,French National Center for Scientific Research |
Sabra A.,University of Bordeaux 1 |
Sabra A.,French National Center for Scientific Research |
And 14 more authors.
Antimicrobial Agents and Chemotherapy | Year: 2014
We characterized two additional membrane transporters (Fur4p and Dal4p) of the nucleobase cation symporter 1 (NCS1) family involved in the uptake transport of pyrimidines and related molecules in the opportunistic pathogenic yeast Candida lusitaniae. Simple and multiple null mutants were constructed by gene deletion and genetic crosses. The function of each transporter was characterized by supplementation experiments, and the kinetic parameters of the uptake transport of uracil were measured using radiolabeled substrate. Fur4p specifically transports uracil and 5-fluorouracil. Dal4p is very close to Fur4p and transports allantoin (glyoxyldiureide). Deletion of the FUR4 gene confers resistance to 5-fluorouracil as well as cross-resistance to triazoles and imidazole antifungals when they are used simultaneously with 5-fluorouracil. However, the nucleobase transporters are not involved in azole uptake. Only fluorinated pyrimidines, not pyrimidines themselves, are able to promote cross-resistance to azoles by both the salvage and the de novo pathway of pyrimidine synthesis. A reinterpretation of the data previously obtained led us to show that subinhibitory doses of 5-fluorocytosine, 5-fluorouracil, and 5-fluorouridine also were able to trigger resistance to fluconazole in susceptible wild-type strains of C. lusitaniae and of different Candida species. Our results suggest that intracellular fluorinated nucleotides play a key role in azole resistance, either by preventing azoles from targeting the lanosterol 14-alpha-demethylase or its catalytic site or by acting as a molecular switch for the triggering of efflux transportCopyright © 2014, American Society for Microbiology. All Rights Reserved.