Cupriavidus metallidurans CH34

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Etude de la résistance de Cupriavidus metallidurans CH34 aux oxyanions sélénite et séléniate : accumulation, localisation et transformation du sélénium.

Etude de la résistance de Cupriavidus metallidurans CH34 aux oxyanions sélénite et séléniate : accumulation, localisation et transformation du sélénium.

DISCUSSION ET CONCLUSION du chapitre I La résistance aux oxyanions de sélénium de C. metallidurans CH34 est déterminée par l’évaluation de leurs toxicités se traduisant par la perturbation ou l’inhibition de la croissance cellulaire de la souche. Nous avons montré une différence de résistance au sélénite et au séléniate chez C. metallidurans CH34. La durée de la phase de latence augmente proportionnellement à la concentration en sélénite présent dans le milieu de culture au moment de l’exposition, comme cela a déjà été montré lors d’une étude précédente (Roux et al., 2001). La phase de latence peut également conduire à une mutation de la souche. En effet, si les nouvelles conditions environnementales sont trop exigeantes, par exemple en présence d’un agent toxique, les micro-organismes ont la capacité de s’adapter par des mutations aléatoires (Wright et al., 2004). Dans ce cas, si la mutation générée est bénéfique pour la bactérie, alors les mutants sélectionnés survivront dans cet environnement sélectif.
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Homéostasie et résistance au cuivre chez Cupriavidus metallidurans CH34 : la protéine CopH et les transporteurs membranaires CusA et CzcA

Homéostasie et résistance au cuivre chez Cupriavidus metallidurans CH34 : la protéine CopH et les transporteurs membranaires CusA et CzcA

la résistance au cuivre chez Pseudomonas syringae (Bender C. L. et Cooksey, D. A. 1986), Enterococcus hirae (Odermatt A. et al. 1992) ou C. metallidurans CH34 (voir paragraphe IV). Un autre exemple est donné par la bactérie Bacillus subtilis, qui fait appel à l’ATPase CopA et la métallo-chaperonne CopZ au travers de l’opéron copZA, en présence de cuivre. La protéine régulatrice CueR induit alors la transcription de l’opéron copZA : l’efflux du métal est alors assuré par l’intervention de la pompe multi-drogues YfmO (Gaballa A. et Helmann, J. D. 2003). L’opéron mer a été étudié et révèle la présence d’un système de détoxication du mercure (Lund, P. A. et al. 1986). L’opéron mer est composé d’un régulateur transcriptionnel MerR, de protéines de transport comme MerT et MerP et d’une protéine appelée MerA impliquée dans la réduction de l’ion mercurique en mercure élémentaire (Fig. 3). Un modèle de résistance au mercure, proposé par Brown dès 1986, implique la prise en charge de Hg(II) par une métallo-chaperonne MerP dès le passage de l’ion à travers la membrane externe de la bactérie. MerP transmet alors le mercure sous la forme Hg(II) à MerT, transporteur localisé dans la membrane interne. Une dernière étape de ce processus de résistance est attribuée au passage de l’ion de MerT à la réductase MerA dans le cytosol. Ainsi ce mécanisme implique paradoxalement une internalisation du mercure avant sa réduction en mercure élémentaire Hg(0) et son évacuation de la cellule par diffusion passive (Brown, N. L. et al. 2002).
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Perception du stress métallique (nickel/cobalt) par le système de signalisation transmembranaire Cnr chez Cupriavidus metallidurans CH34

Perception du stress métallique (nickel/cobalt) par le système de signalisation transmembranaire Cnr chez Cupriavidus metallidurans CH34

4.1.3.2 Déterminants situés sur le plasmide pMOL30 Le plasmide pMOL30 comprend le locus pbrTRABCD codant pour la résistance au plomb (Borremans et al., 2001), l’opéron merRTPADE qui intervient dans la défense contre les ions mercure [voir section 2.4.4 page 38] et l’opéron copSRABCD impliqué dans l’efflux des ions cuivre (Mergeay, 2000). Il contient de plus les gènes czcNICBADRSE qui codent la pompe CzcCBA, un système d’efflux RND de type HME [voir section 2.3.2 page 35] (Nies, 1995), CzcD une protéine CDF (Anton et al., 1999), CzcRS un système à deux composants régulant la transcription des gènes czcCBA (Grosse et al., 1999), CzcE une protéine périplasmique dont il a été montré qu’elle était spécifique du cuivre (Zoropogui et al., 2008), CzcI et CzcN dont la fonction est inconnue. Adjacent à ce locus, le gène czcP code une ATPase de type P (Scherer et Nies, 2009). pMOL30 inclut aussi l’opéron ncc impliqué dans la résistance au nickel, cobalt et cadmium. .Il est silencieux dans CH34 par suite d’une mutation introduisant un décalage du cadre de lecture (Nies et al., 2006). silencieux dans la souche CH34. Ce déterminant, qui possède de fortes homologies avec l’opéron cnr décrit dans la partie suivante, existe également dans la souche 31A sur le plasmide pTOM9 où il est fonctionnel [voir section 4.2.2.1 page 68] (Schmidt et Schlegel, 1994).
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2-Ketogluconate Kinase from Cupriavidus necator H16: Purification, Characterization, and Exploration of Its Substrate Specificity

2-Ketogluconate Kinase from Cupriavidus necator H16: Purification, Characterization, and Exploration of Its Substrate Specificity

M of imidazole retained 90% of initial activity after one month, whereas protein samples in the Figure 1. Reaction catalyzed by 2-ketogluconate kinase (KGUK). 2-ketogluconate kinase was first discovered as an inducible activity in 1953 in Aerobacter cloacae [ 32 ] and then in Pseudomonas fluorescens [ 24 ]. The enzyme’s product, 2-ketogluconate-6-phosphate, was isolated and described at the same time [ 23 ]. Later, four other KGUKs were identified from: (i) the Gram-positive L. mesenteroides [ 19 ], (ii) Aerobacter aerogenes (nowadays classified as Klebsiella pneumoniae) [ 25 ], (iii) Hydrogenomonas eutropha H16 (newer and alternative designations are Ralstonia eutropha H16 or Cupriavidus necator H16) [ 33 ], and (iv) P. aeruginosa [ 20 , 28 ]. To the best of our knowledge, however, no studies on the substrate specificity of any bacterial KGUK have been published so far. We focused our attention on the kinase from C. necator, the complete genome sequence of which has been published [ 34 ], and we abbreviated this enzyme as KGUK Cnec . In this work, we cloned, overexpressed, and purified the recombinant N-terminal his-tagged 2-ketogluconate kinase from C. necator (KGUK Cnec ) in Escherichia coli. For the first time, its substrate specificity was studied with different commercially available sugars and with various synthetic analogues of the natural substrate 2-ketogluconate. Finally, a preparative scale of the 2-ketogluconate-6-phosphate was performed to demonstrate the synthetic potential of this enzyme.
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Transcriptomic profiling of Burkholderia phymatum STM815, Cupriavidus taiwanensis LMG19424 and Rhizobium mesoamericanum STM3625 in response to Mimosa pudica root exudates illuminates the molecular basis of their nodulation competitiveness and symbiotic ev

Transcriptomic profiling of Burkholderia phymatum STM815, Cupriavidus taiwanensis LMG19424 and Rhizobium mesoamericanum STM3625 in response to Mimosa pudica root exudates illuminates the molecular basis of their nodulation competitiveness and symbiotic evolutionary history

Mimosa pudica is a legume that has the rare ability to be nodulated naturally by both alpha (Rhizobium spp.) and beta-rhizobia (Burkholderia, Cupriavidus). Diversity studies showed that proportions between beta- and alpha- rhizobia hosted in nodules of M. pudica vary significantly in different geographical locations. For example, Burkhol- deria were found to be predominant in nodules of M. pudica in Barro Colorado Island and in French Guiana [10, 32], whereas the proportions of Burkholderia and Cupriavidus symbionts were more equal in Costa Rica, China and India [18, 20, 24], and finally Cupriavidus was found to be predominant in nodules of M. pudica in Taiwan and in New Caledonia [23, 33]. Several parameters can help explain the proportions of symbionts in nodules of M. pudica in worldwide diversity studies, but soil char- acteristics, especially the presence of combined nitrogen affect strain competitiveness [34]. In a previous study [35], we made a large survey of strain nodulation competitive- ness between Burkholderia, Cupriavidus and Rhizobium species and showed that B. phymatum and B. tuberum sv. mimosae are the most competitive species on Mimosa pudica, but Cupriavidus taiwanensis could compete with Burkholderia when tested on specific M. pudica genotypes (on variety unijuga from Taiwan where Cupriavidus domi- nates in nodules of this variety). In the case of Rhizobium species, all species were poorly competitive, despite the fact that R. mesoamericanum are frequently found in diversity studies, although in small proportions, such as in Costa Rica [18], Mexico [36], New Caledonia [23] and French Guiana [10], which raises questions about their capacity to be maintained as M. pudica symbionts. The only case of a Rhizobium species dominating in the nod- ules of M. pudica is R. altiplani in central Brazil [37].
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Biosynthesis and characterization of polyhydroxyalkanoate containing high 3-hydroxyhexanoate monomer fraction from crude palm kernel oil by recombinant Cupriavidus necator

Biosynthesis and characterization of polyhydroxyalkanoate containing high 3-hydroxyhexanoate monomer fraction from crude palm kernel oil by recombinant Cupriavidus necator

how this access benefits you. Your story matters. Citation Wong, Yoke-Ming, Christopher J. Brigham, ChoKyun Rha, Anthony J. Sinskey, and Kumar Sudesh. “Biosynthesis and Characterization of Polyhydroxyalkanoate Containing High 3-Hydroxyhexanoate Monomer Fraction from Crude Palm Kernel Oil by Recombinant Cupriavidus Necator.” Bioresource Technology 121 (October 2012): 320–327.

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2-Ketogluconate Kinase from Cupriavidus necator H16: Purification, Characterization, and Exploration of Its Substrate Specificity

2-Ketogluconate Kinase from Cupriavidus necator H16: Purification, Characterization, and Exploration of Its Substrate Specificity

2 University of Stuttgart, Institute of Microbiology, D-70569 Stuttgart, Germany * Correspondence: christine.helaine@uca.fr (C.G.-H.); georg.sprenger@imb.uni-stuttgart.de (G.A.S.) Received: 7 June 2019; Accepted: 27 June 2019; Published: 28 June 2019    Abstract: We have cloned, overexpressed, purified, and characterized a 2-ketogluconate kinase (2-dehydrogluconokinase, EC 2.7.1.13) from Cupriavidus necator (Ralstonia eutropha) H16. Exploration of its substrate specificity revealed that three ketoacids (2-keto-3-deoxy-d-gluconate, 2-keto-d-gulonate, and 2-keto-3-deoxy-d-gulonate) with structures close to the natural substrate (2-keto-d-gluconate) were successfully phosphorylated at an efficiency lower than or comparable to 2-ketogluconate, as depicted by the measured kinetic constant values. Eleven aldo and keto monosaccharides of different chain lengths and stereochemistries were also assayed but not found to be substrates. 2-ketogluconate-6-phosphate was synthesized at a preparative scale and was fully characterized for the first time.
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Rhizobium metallidurans sp. nov., a symbiotic heavy metal resistant bacterium isolated from the Anthyllis vulneraria Zn-hyperaccumulator

Rhizobium metallidurans sp. nov., a symbiotic heavy metal resistant bacterium isolated from the Anthyllis vulneraria Zn-hyperaccumulator

78 89 0.005 Fig. 1. Maximum-likelihood phylogenetic tree based on 16S rRNA gene sequences, showing the relationships between strain ChimEc512 T and the most closely related reference strains. The analysis was based on 1330 nt. GenBank accession numbers are given in parentheses. The significance of each branch is indicated by a bootstrap value calculated for 1000 replicates. Bootstrap values greater than 50 % are indicated. M. metallidurans STM2683 T was used as an outgroup (data not shown). Bar,

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Metabolic engineering of Cupriavidus necator for heterotrophic and autotrophic alka(e)ne production

Metabolic engineering of Cupriavidus necator for heterotrophic and autotrophic alka(e)ne production

Heterologous expression into Escherichia coli of these two genes from Nostoc punctiforme PCC73102 allowed alka(e)ne pro- duction up to 300 mg/l (primarily C15 alkane and C17 alkene) with more than 80% of the hydrocarbons found outside of the cells ( Schirmer et al., 2010 ). Alka(e)ne content in Synechocystis sp. PCC6803 mutants overexpressing native alkane biosynthetic genes was 1.1% of dry weight cell and alka(e)ne production in photo- bioreactor reached 26 mg/l in 10 days ( Wang et al., 2013 ). In Sy- nechococcus sp. PCC 7002, overexpressing a heterologous alkane pathway allowed to reach 5% of cell dry weight (CDW) of alka(e)ne ( Reppas and Ridley, 2010 ). Alka(e)ne production was also obtained in Saccharomyces cerevisiae and Cupriavidus necator mutant strains Contents lists available at ScienceDirect
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In vitro activity of 20 antibiotics against Cupriavidus clinical strains

In vitro activity of 20 antibiotics against Cupriavidus clinical strains

In conclusion, our study showed that minocycline and cefepime exhibited the best in vitro activities against Cupriavidus strains. Meropenem, aminoglycosides and polymyxins, often considered antibiotics of last resort against infections caused by Gram- negative bacilli, do not have reliable activity against Cupriavidus. Perhaps resistance to these agents confers a selective advantage to Cupriavidus and therefore it may emerge in clinical scenarios where these agents are used, such as in patients with CF. Imipenem was more active than meropenem and cefotaxime/cef- triaxone was more active than ceftazidime. Ceftolozane/tazobac- tam had reasonable activity against Cupriavidus, whereas the novel inhibitor avibactam does not seem to add to the activity of
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