Staphylococcus aureus NAD kinase is required for envelop and antibiotic stress responses

International audienceGlobal burden of infectious diseases and antimicrobial resistance are major public health issues calling for innovative control measures. Bacterial NAD kinase (NADK) is a crucial enzyme for production of NADP(H) and growth. In Staphylococcus aureus, NADK promotes pathogenesis by supporting production of key virulence determinants. Here, we find that knockdown of NADK by CRISPR interference sensitizes S. aureus to osmotic stress and to stresses induced by antibiotics targeting the envelop as well as replication, transcription and translation. Thus, NADK represents a promising target for the development of inhibitors which could be used in combination with current antibiotics

Emerging Evasion Mechanisms of Macrophage Defenses by Pathogenic Bacteria

International audienceMacrophages participate to the first line of defense against infectious agents. Microbial pathogens evolved sophisticated mechanisms to escape macrophage killing. Here, we review recent discoveries and emerging concepts on bacterial molecular strategies to subvert macrophage immune responses. We focus on the expanding number of fascinating subversive tools developed by Listeria monocytogenes, Staphylococcus aureus, and pathogenic Yersinia spp., illustrating diversity and commonality in mechanisms used by microorganisms with different pathogenic lifestyles

Complete Genome Sequences of Bioluminescent Staphylococcus aureus Strains Xen31 and Xen36, Derived from Two Clinical Isolates

International audienceHere, we report complete genome sequences of two clinical isolates of Staphylococcus aureus , namely, Xen31 and Xen36, which have been genetically modified to express an optimized Photorhabdus luminescens luciferase operon. Xen31 and Xen36 are bioluminescent strains used widely for investigation of bacterial pathogenesis, drug discovery, and development of novel therapies

Study of the recent morphodynamic and internal architecture of the Sillon de Talbert gravel barrier spit using GPR method (Brittany, France)

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NAD kinase promotes Staphylococcus aureus pathogenesis by supporting production of virulence factors and protective enzymes

International audienceNicotinamide adenine dinucleotide phosphate (NADPH) is the primary electron donor for reductive reactions that are essential for the biosynthesis of major cell components in all organisms. Nicotinamide adenine dinucleotide kinase (NADK) is the only enzyme that catalyzes the synthesis of NADP(H) from NAD(H). While the enzymatic properties and physiological functions of NADK have been thoroughly studied, the role of NADK in bacterial pathogenesis remains unknown. Here, we used CRISPR interference to knock down NADK gene expression to address the role of this enzyme in Staphylococcus aureus pathogenic potential. We find that NADK inhibition drastically decreases mortality of zebrafish infected with S. aureus. Furthermore, we show that NADK promotes S. aureus survival in infected macrophages by protecting bacteria from antimicrobial defense mechanisms. Proteome-wide data analysis revealed that production of major virulence-associated factors is sustained by NADK. We demonstrate that NADK is required for expression of the quorum-sensing response regulator AgrA, which controls critical S. aureus virulence determinants. These findings support a key role for NADK in bacteria survival within innate immune cells and the host during infection

Nouvelle sonde chimique ciblant la NAD kinase bactérienne

International audienceNicotinamide adenine dinucleotide (NAD) kinases are essential and ubiquitous enzymes involved in the tight regulation of NAD/nicotinamide adenine dinucleotide phosphate (NADP) levels in many metabolic pathways. Consequently, they represent promising therapeutic targets in cancer and antibacterial treatments. We previously reported diadenosine derivatives as NAD kinase inhibitors with bactericidal activities on Staphylococcus aureus. Among them, one compound (namely NKI1) was found effective in vivo in a mouse infection model. With the aim to gain detailed knowledge about the selectivity and mechanism of action of this lead compound, we planned to develop a chemical probe that could be used in affinity-based chemoproteomic approaches. Here, we describe the first functionalized chemical probe targeting a bacterial NAD kinase. Aminoalkyl functional groups were introduced on NKI1 for further covalent coupling to an activated Sepharose TM matrix. Inhibitory properties of functionalized NKI1 derivatives together with X-ray characterization of their complexes with the NAD kinase led to identify candidate compounds that are amenable to covalent coupling to a matrix

Synthesis and structure-activity relationship studies of original cyclic diadenosine derivatives as nanomolar inhibitors of NAD kinase from pathogenic bacteria

International audienceNicotinamide adenine dinucleotide kinases (NAD kinases) are essential and ubiquitous enzymes involved in the production of NADP(H) which is an essential cofactor in many metabolic pathways. Targeting NAD kinase (NADK), a rate limiting enzyme of NADP biosynthesis pathway, represents a new promising approach to treat bacterial infections. Previously, we have produced the first NADK inhibitor active against staphylococcal infection. From this linear di-adenosine derivative, namely NKI1, we designed macrocyclic analogues. Here, we describe the synthesis and evaluation of an original series of cyclic diadenosine derivatives as NADK inhibitors of two pathogenic bacteria, Listeria monocytogenes and Staphylococcus aureus. The nature and length of the link between the two adenosine units were examined leading to sub-micromolar inhibitors of NADK1 from L. monocytogenes, including its most potent in vitro inhibitor reported so far (with a 300-fold improvement compared to NKI1)

ESS Elliptical Cavities and Cryomodules

The accelerator of the European Spallation Source (ESS) is a 5 MW proton linac to be built in Lund Sweden. Its superconducting section is composed of 3 cavity families: double spoke resonators, medium beta and high beta elliptical multi-cell cavities. This paper presents the electromagnetic and mechanical design of the elliptical cavities. Both elliptical families are housed in 4-cavity cryomodules which share a common design and set of components which will be described here

Structure-based design of NAD+ analogues targeting bacterial NAD kinases, promising targets for new antibiotics

International audienceMulti-drug resistance is a major public health problem that requires the urgent development of new antibiotics and therefore the identification of novel bacterial targets. The activity of nicotinamide adenine dinucleotide kinase, NADK, is essential in all bacteria tested so far, including many human pathogens that display antibiotic resistance leading to failure of current treatments. Inhibiting NADK is therefore a promising and innovative antibacterial strategy since there is currently no drug on the market targeting this enzyme. Through a drug design approach based on substrate-derived fragments, we have recently developed NAD+-competitive inhibitors of NADKs, which displayed in vivo activity against Staphylococcus aureus or Pseudomonas aeruginosa in animal models of infection [1-3].Funding and supports: Agence Nationale de la Recherche (ANR-17-CE18-0011-02), Institut Pasteur, Centre National de la Recherche Scientifique (CNRS), Institut National de la Santé et de la Recherche Médicale (INSERM), University of Montpellier.References: [1] Clément DA, Leseigneur C, Gelin M, Coelho D, Huteau V, Lionne C, Labesse G, Dussurget O, Pochet S (2020) New chemical probe targeting bacterial NAD kinase. Molecules. doi: 10.3390/molecules25214893.[2] Gelin M, Paoletti J, Nahori MA, Huteau V, Leseigneur C, Jouvion G, Dugué L, Clément D, Pons JL, Assairi L, Pochet S, Labesse G, Dussurget O (2020) From substrate to fragments to inhibitor active in vivo against Staphylococcus aureus. ACS Infect Dis. doi: 10.1021/acsinfecdis.9b00368.[3] Rahimova R, Nogaret P, HuteauV, Gelin M, Clément D, Labesse G, Pochet S, Blanc-Potard A, Lionne C (2022) Structure-based design, synthesis and biological evaluation of a NAD+ analogue targeting Pseudomonas aeruginosa NAD kinase. In Preparation

Results of CEA Tests of SARAF Cavities Prototypes

International audienceCEA is committed to delivering a Medium Energy Beam Transfer line and a superconducting linac (SCL) for SARAF accelerator in order to accelerate 5mA beam of either protons to 35 MeV or deuterons to 40 MeV. The SCL consists in 4 cryomodules. The first two cryomodules host 6 & 7 half-wave resonator (HWR) low beta cavities (β = 0.09) at 176 MHz, and the last two crymodules host 7 HWR medium beta cavities (β = 0.18). The low beta prototype was qualified, the medium beta is being qualified. The results of the RF tests will be presented in this poster