Two-Component Systems of Mycobacterium tuberculosis as potential targets for drug development

Tuberculosis, caused by Mycobacterium tuberculosis, is a global health problem with approximately two million deaths every year. Furthermore, up to one-third of the world population is infected with latent form of this bacterium.Existing anti-tuberculosis therapies are directed against actively replicating bacteria, while there is no particular treatment for latent tuberculosis infection. Bacterial two-component systems (TCSs) are pleiotropic and play a central role in the adaptation of pathogenic bacteria to the environment prevailing within host tissues. TCS allow microorganisms to sense and respond to changes in many different environmental conditions therefore are consideredpotential pharmacological targets for the developmentof novel antimycobacterial drugs.In this work, we review the current knowledge of the TCSs of Mycobacterium tuberculosis. We discuss their role in bacterial pathogenesis and virulence. We pay special attention to the DosS/DosT/DosR TCS, emphasizing its importance in latent tuberculosis development

The DosRST two-component system of Mycobacterium tuberculosis: Characterizing the activation mechanism of DosR response regulator as a potential target for novel antimycobacterial drugs

La tuberculosi, la malaltia infecciosa causada per Mycobacterium tuberculosis, es un problema de salut global que provoca aproximadament 2 milions de morts anuals. Un terç de la població mundial es troba crònicament infectada amb Mycobacterium tuberculosis però no mostra símptomes clínics encara que té un risc d’un 10% de desenvolupar la malaltia, la qual cosa representa un reservori incontrolable de tuberculosi. En aquesta condició asimptomàtica, coneguda com a tuberculosi latent, Mycobacterium tuberculosis es localitza en lesions granulomatoses a l’hoste i és resistent als medicaments antimicobacterians existents en l’actualitat. En bacteris, els sistemes reguladors de dos components son un conjunt de proteïnes implicades en l’adaptació a canvis en l’entorn del microorganisme. Un sistema de dos components típic consta d’una histidina quinasa unida a membrana que té un paper essencial com a sensor dels canvis ambientals i un regulador transcripcional citosòlic que exerceix la seva funció controlant l’expressió de gens diana. Aquest parell de proteïnes funciona com un interruptor molecular que controla diferents respostes adaptatives a canvis a l’ambient cel•lular. Mycobacterium tuberculosis té 11 sistemes de dos components complets. El sistema DosRST, composat per un regulador transcripcional, DosR, i dues histidines quinases, DosS i DosT, té un paper estel•lar en l’adaptació de Mycobacterium tuberculosis a la tuberculosi latent. DosS i DosT s’autofosforilen en residus conservats d’histidina i ambdues proteïnes transfereixen aquesta un unitat de fosfat al residu d’àcid aspàrtic en posició 54 del regulador DosR. La fosforilació d’Asp54 és un interruptor que activa DosR i incrementa la seva afinitat per als promotors dels gens que regula. Les treonines 198 i 205 de DosR tenen un paper crucial en la dimerització de DosR i en la seva unió al DNA. Les dinàmiques moleculars realitzades amb la proteïna salvatge DosR i amb versions mutants mostren diferències notables en la formació del dímer actiu. També mostren una reducció o abolició completa de les interaccions proteïna-DNA a causa de les repulsions generades pels residus mutants carregats negativament. Encara més, les substitucions en Thr198 i Thr205 tenen un important efecte en la fosforilació química i enzimàtica de DosR així com també en la seva defosforilació catalitzada per DosS. El sistema de dos components DosRST és una bona diana per al desenvolupament de nous compostos amb activitat antimicobacteriana contra formes dorments de Mycobacterium tuberculosis. S’ha iniciat un programa de recerca dirigit al desenvolupament d’inhibidors específics de la proteïna reguladors DosR, usant com a punt de partida compostos comercials estructuralment relacionats amb un derivat fenilcumarínic que ha estat descrit com a molècula que interfereix en la interacció DosR-DNA.La tuberculosis, la enfermedad infecciosa causada por Mycobacterium tuberculosis, es un problema de salud global que provoca aproximadamente 2 millones de muertes anuales. Un tercio de la población mundial se encuentra crónicamente infectada con Mycobacterium tuberculosis pero no muestra síntomas clínicos aunque tiene un riesgo de un 10% de desarrollar la enfermedad, lo que representa un reservorio incontrolable de tuberculosis. En esta condición asintomática, conocida como tuberculosis latente, Mycobacterium tuberculosis se localiza en lesiones granulomatosas en el huésped y es resistente a los medicamentos antimicobacterianos existentes en la actualidad. En bacterias, los sistemas regulatorios de dos componentes son un conjunto de proteínas implicadas en la adaptación a cambios en el entorno del microorganismo. Un sistema de dos componentes típico consta de una histidina quinasa unida a membrana que tiene un papel esencial como sensor de los cambios ambientales y un regulador transcripcional citosólico que ejerce su función controlando la expresión de genes diana. Este par de proteínas funciona como un interruptor molecular que controla distintas respuestas adaptativas a cambios en el ambiente celular. Mycobacterium tuberculosis tiene 11 sistemas de dos componentes completos. El sistema DosRST, compuesto por un regulador transcripcional, DosR, y dos histidinas quinasas, DosS y DosT, juega un papel estelar en la adaptación de Mycobacterium tuberculosis a la tuberculosis latente. DosS y DosT se autofosforilan en residuos conservados de histidina y ambas proteínas transfieren esta unidad de fosfato al residuo de ácido aspártico en posición 54 del regulador DosR. La fosforilación de Asp54 es un interruptor que activa a DosR e incrementa su afinidad por los promotores de los genes que regula. Las treoninas 198 y 205 de DosR juegan un papel crucial en la dimerización de DosR y en su unión al DNA. Las dinámicas moleculares realizadas con la proteína salvaje DosR y con versiones mutantes muestran diferencias notables en la formación del dímero activo. También muestran una reducción o abolición completa de las interacciones proteína-DNA a causa de las repulsiones generadas por los residuos mutantes cargados negativamente. Más aún, las sustituciones en Thr198 y Thr205 tienen un importante efecto en la fosforilación química y enzimática de DosR así como también en su defosforilaición catalizada por DosS. El sistema de dos componentes DosRST es una buena diana para el desarrollo de nuevos compuestos con actividad antimicobacteriana contra formas durmientes de Mycobacterium tuberculosis. Se ha iniciado un programa de investigación dirigido al desarrollo de inhibidores específicos de la proteína reguladora DosR, usando como punto de partida compuestos comerciales estructuralmente relacionados con un derivado fenilcumarínico que ha sido descrito como molécula que interfiere en la interacción DosR-DNA.Tuberculosis, the infectious disease caused by Mycobacterium tuberculosis, is a global health problem with approximately two million deaths annually. One-third of the world population is chronically infected with Mycobacterium tuberculosis but do not show clinical symptoms although there is a 10% risk to development active disease, representing an uncontrollable reservoir of tuberculosis. In this asymptomatic condition, referred to as latent tuberculosis, Mycobacterium tuberculosis is located within granulomatous lesions in the host and is resistant to currently available antimycobacterial drugs. Two-component regulatory systems in bacteria are a major class of signal transduction proteins involved in adaptation to environmental changes. Typical system contains a membrane-bound histidine kinase that plays a crucial role in sensing environmental stimuli, and a cytosolic response regulator. This pair of proteins functions as a molecular switch that controls diverse adaptive environmental responses. Mycobacterium tuberculosis has eleven complete two-component systems. The DosRST system, composed of a response regulator, DosR, and two histidine kinases, DosS and DosT, plays a key role in Mycobacterium tuberculosis adaptation to latent tuberculosis. DosS and DosT autophosphorylate at conserved histidine residues and both proteins transfer this phosphor moiety to aspartic acid residue 54 of DosR. The phosphorylation of Asp54 serves as a switch to activate DosR and to increase the affinity for its cognate DNA promoters. Threonines 198 and 205 of DosR play a crucial role in DosR dimerization and DNA binding. The molecular dynamics with wild type and mutant version of DosR show different stability in the formation of the active DosR dimer. They also show the reduction or the abolishment of protein-DNA interactions because of the repulsions generated by negatively charged mutated residues. Moreover, substitutions in threonines 198 and 205 of DosR have a relevant effect on the chemical and enzymatic phosphorylation of DosR and on its DosS-catalysed dephosphorylation. The DosRST two-component system is a good target for the development of novel antimycobacterial drugs against dormant forms of M. tuberculosis. A structure-based discovery programme of inhibitors of DosR response regulator has been initiated with commercially available compounds showing a certain degree of similarity with a phenylcoumarin derivative previously described as DosR-DNA interfering molecule

Chemical order and crystallographic texture of FePd:Cu thin alloy films

FePd thin films have been recently considered as promising material for high-density magnetic storage devices. However, it is necessary to find a proper method of fabrication for the (001)-textured and chemically well-ordered alloy. In this paper, we present the detailed investigations of lattice parameters, chemical order degree, grain sizes and crystallographic texture, carried out on FePd alloys with 10 at.% of Cu addition. The initial [Cu(0.2 nm)/Fe(0.9 nm)/Pd(1.1 nm)]x5 multilayers were thermally evaporated in an ultra-high vacuum on MgO(100), Si(100), Si(111) and Si(100) covered by 100 nm thick layer of amorphous SiO2. In order to obtain homogeneous FePd:Cu alloy, the multilayers were annealed in two different ways. First, the samples were rapidly annealed in nitrogen atmosphere at 600oC for 90 seconds. Next, the long annealing in a high vacuum for 1 hour at 700oC was done. This paper focuses on quantitative investigations of the chemical order degree and crystallographic texture of ternary FePd:Cu alloys deposited on four different substrates. In order to obtain both quantities we have taken a novel approach to consider the problem of dopant atoms located in the FePd structure. The studies of the structure were done using X-Ray Diffraction (XRD) performed with synchrotron radiation and pole figures measurements. We have found that the addition of Cu changes the FePd lattice parameters and lattice distortion. We have also shown, that using different substrates it is possible to obtain a FePd:Cu alloy with different chemical order and texture. Moreover, it was observed that texture category is substrate dependent

Tailoring of magnetic properties of NiO/Ni composite particles fabricated by pulsed laser irradiation

We present NiO/Ni composite particles with face-centered cubic (fcc) structure prepared by a pulsed laser irradiation of NiO nanoparticles dispersed in liquid. The sizes of particles and the Ni content in NiO/Ni composites were controlled by tuning the laser parameters, such as laser fluence and irradiation time. We found that the weight fraction of Ni has a significant impact on magnetic properties of composite particles. Large exchange bias (HEB) and coercivity field (HC) were observed at 5 K due to the creation of heterojunctions at interfaces of ferromagnetic Ni and antiferromagnetic NiO. For the NiO/Ni composites with 80% of NiO we have observed the largest values of exchange bias (175 Oe) and coercive field (950 Oe), but the increase of Ni weight fraction resulted in the decrease of both HC and HEB values

Is obesity more likely among children sharing a household with an older child with obesity?

Objectives We used a dynamic method of identifying household members from Electronic Health Records (EHRs) linked to National Child Measurement Programme (NCMP) data to estimate the likelihood of children with obesity sharing a household with an older child with obesity, accounting for individual and household characteristics. Methods We included 126,829 NCMP participants in four London boroughs and assigned households from encrypted Unique Property reference Numbers (UPRNs) at NCMP date for 115,466 (91%). We categorised the ethnic-adjusted body mass index of the youngest and oldest household child (underweight/healthy weight<91st, ≥91st to <98th overweight, obesity≥98th centile) and explored associations of the youngest child’s weight status with: oldest child’s weight status, number of household children (two, three or ≥4), youngest child’s sex, ethnicity and school year of NCMP participation (reception or year 6). We estimated adjusted odds ratios (aOR) and 95% confidence intervals (CI) of obesity in the youngest child. Results 19,702 UPRNs were shared by two or more NCMP participants (youngest children: 51.2% male, 69.5% reception). 10.4% of youngest (95% CI: 10.0,10.9) and 13.0% of oldest (12.5,14.3) children were living with obesity. One third of youngest children with obesity shared a household with another child with obesity (33.2%; 31.2,35.2), compared with 9.2% (8.8,9.7) of those with a healthy weight. Youngest children living with an older child with overweight (aOR: 2.33; 95% CI: 2.06,2.64) or obesity (4.59, 4.10,5.14), those from South Asian ethnic backgrounds (1.89; 1.64,2.19) or taking part in NCMP in year 6 (2.21; 2.00,2.43) were more likely, and girls (0.73; 0.67,0.81), children living with just one other child (0.87; 0.77,0.98) and from Black ethnic backgrounds (0.78; 0.66,0.93) less likely, to be living with obesity. Conclusion Linked EHRs can provide novel insights into the shared weight status of children sharing the same household. Further qualitative research is needed to understand how household food practices may vary by other household characteristics to improve our understanding of how the home environment influences childhood obesity

In vivo effects of romidepsin on T-Cell activation, apoptosis and function in the BCN02 HIV-1 kick&Kill clinical trial

Romidepsin (RMD) is a well-characterized histone deacetylase inhibitor approved for the treatment of cutaneous T-cell lymphoma. in vitro and in vivo studies have demonstrated that it is able to induce HIV-1 gene expression in latently infected CD4+ T cells from HIV-1+ individuals on suppressive antiretroviral therapy. However, in vitro experiments suggested that RMD could also impair T-cell functionality, particularly of activated T cells. Thus, the usefulness of RMD in HIV-1 kick&kill strategies, that aim to enhance the immune system elimination of infected cells after inducing HIV-1 viral reactivation, may be limited. In order to address whether the in vitro observations are replicated in vivo, we determined the effects of RMD on the total and HIV-1-specific T-cell populations in longitudinal samples from the BCN02 kick&kill clinical trial (NCT02616874). BCN02 was a proof-of-concept study in 15 early treated HIV-1+ individuals that combined MVA.HIVconsv vaccination with three weekly infusions of RMD given as a latency reversing agent. Our results show that RMD induced a transient increase in the frequency of apoptotic T cells and an enhanced activation of vaccine-induced T cells. Although RMD reduced the number of vaccine-elicited T cells secreting multiple cytokines, viral suppressive capacity of CD8+ T cells was preserved over the RMD treatment. These observations have important implications for the design of effective kick&kill strategies for the HIV-1 cure