Lipocalin 2 (Lcn2) interferes with iron uptake by Brucella abortus and dampens immunoregulation during infection of RAW 264.7 macrophages

Lipocalin 2 (Lcn2) is an important innate immunity component against bacterial pathogens. In this study, we report that Lcn2 is induced by Brucella (B.) abortus infection and significantly contributes to the restriction of intracellular survival of Brucella in macrophages. We found that Lcn2 prevented iron uptake by B. abortus through two distinct mechanisms. First, Lcn2 is secreted to capture bacterial siderophore(s) and abrogate iron import by Brucella. Second, Lcn2 decreases the intracellular iron levels during Brucella infection, which probably deprives the invading Brucella of the iron source needed for growth. Suppression of Lcn2 signalling resulted in a marked induction of anti‐inflammatory cytokine, interleukin 10, which was shown to play a major role in Lcn2‐induced antibrucella immunity. Similarly, interleukin 6 was also found to be increased when Lcn2 signalling is abrogated; however, this induction was thought to be an alternative pathway that rescues the cell from infection when the effective Lnc2 pathway is repressed. Furthermore, Lcn2 deficiency also caused a marked decrease in brucellacidal effectors, such as reactive oxygen species and nitric oxide but not the phagolysosome fusion. Taken together, our results indicate that Lcn2 is required for the efficient restriction of intracellular B. abortus growth that is through limiting iron acquisition and shifting cells to pro‐inflammatory brucellacidal activity in murine macrophages.     

Transformation of Δ<Superscript>4</Superscript>-3-ketosteroids by free and immobilized cells of <Emphasis Type="Italic">Rhodococcus erythropolis</Emphasis> actinobacterium

9α-Hydroxy derivatives were prepared from 11 steroids of androstane and pregnane series using Rhodococcus erythropolis VKPM Ac-1740 culture with 0.5–10 g/l substrate concentration in the reaction mixture. 9α-Monohydroxylation proceeded regardless of the substituent structure at C17. However, the structure of the steroid molecule influenced the time of complete conversion of the substrate and the yield of the transformation product. 9α-Hydroxy-androstenedione was obtained in 35 h in a yield of 85% when the maximum concentration of androstenedione (AD) was 10 g/l. 9α-Hydroxy-AD was also formed by the actinobacterium cells entrapped in poly(vinyl alcohol) cryogel beads. Nine successive transformation cycles were carried out using immobilized cells at 4.0 g/l concentration of AD in the medium. The yield of 9α-hydroxy-AD formed during six cycles (from two to eight with the duration of each cycle for 22–24 h) was 98%.     

Aquaporin Trafficking in Plant Cells: An Emerging Membrane‐Protein Model

Aquaporins (AQPs) are channel proteins that facilitate the transport of water and small solutes across biological membranes. In plants, AQPs exhibit a high multiplicity of isoforms in relation to a high diversity of sub‐cellular localizations, at the plasma membrane (PM) and in various intracellular compartments. Some members also exhibit a dual localization in distinct cell compartments, whereas others show polarized or domain‐specific expression at the PM or tonoplast, respectively. A diversity of mechanisms controlling the routing of newly synthesized AQPs towards their destination membranes and involving diacidic motifs, phosphorylation or tetramer assembly is being uncovered. Recent approaches using single particle tracking, fluorescence correlation spectroscopy and fluorescence recovery after photobleaching have, in combination with pharmacological interference, stressed the peculiarities of AQP sub‐cellular dynamics in environmentally challenging conditions. A role for clathrin and sterol‐rich domains in cell surface dynamics and endocytosis of PM AQPs was uncovered. These recent advances provide deep insights into the cellular mechanisms of water transport regulation in plants. They also point to AQPs as an emerging model for studying the sub‐cellular dynamics of plant membrane proteins .     

Crystal structure of malonyl CoA-Acyl carrier protein transacylase from Xanthomanous oryzae pv. oryzae and its proposed binding with ACP

Xanthomonas oryzae pv. oryzae (Xoo) is a plant bacterial pathogen that causes bacterial blight (BB) disease, resulting in serious production losses of rice. The crystal structure of malonyl CoA-acyl carrier protein transacylase (XoMCAT), encoded by the gene fabD (Xoo0880) from Xoo, was determined at 2.3 Å resolution in complex with N-cyclohexyl-2-aminoethansulfonic acid. Malonyl CoA-acyl carrier protein transacylase transfers malonyl group from malonyl CoA to acyl carrier protein (ACP). The transacylation step is essential in fatty acid synthesis. Based on the rationale, XoMCAT has been considered as a target for antibacterial agents against BB. Protein-protein interaction between XoMCAT and ACP was also extensively investigated using computational docking, and the proposed model revealed that ACP bound to the cleft between two XoMCAT subdomains.     

Physical Activity in Vietnam: Estimates and Measurement Issues

IntroductionOur aims were to provide the first national estimates of physical activity (PA) for Vietnam, and to investigate issues affecting their accuracy.MethodsMeasurements were made using the Global Physical Activity Questionnaire (GPAQ) on a nationally-representative sample of 14706 participants (46.5% males, response 64.1%) aged 25−64 years selected by multi-stage stratified cluster sampling.ResultsApproximately 20% of Vietnamese people had no measureable PA during a typical week, but 72.9% (men) and 69.1% (women) met WHO recommendations for PA by adults for their age. On average, 52.0 (men) and 28.0 (women) Metabolic Equivalent Task (MET)-hours/week (largely from work activities) were reported. Work and total PA were higher in rural areas and varied by season. Less than 2% of respondents provided incomplete information, but an additional one-in-six provided unrealistically high values of PA. Those responsible for reporting errors included persons from rural areas and all those with unstable work patterns. Box-Cox transformation (with an appropriate constant added) was the most successful method of reducing the influence of large values, but energy-scaled values were most strongly associated with pathophysiological outcomes.ConclusionsAround seven-in-ten Vietnamese people aged 25–64 years met WHO recommendations for total PA, which was mainly from work activities and higher in rural areas. Nearly all respondents were able to report their activity using the GPAQ, but with some exaggerated values and seasonal variation in reporting. Data transformation provided plausible summary values, but energy-scaling fared best in association analyses.     

A novel nucleotide kinase encoded by gene 1.7 of bacteriophage T7

Gene 1.7 of bacteriophage T7 confers sensitivity of both phage T7 and its host Escherichia coli to dideoxythymidine (ddT). We have purified the product of gene 1.7, gp1.7. It exists in two forms of molecular weight 22 181 and 17 782. Only the C‐terminal half of the protein is required to confer ddT sensitivity. We show that gp1.7 catalyses the phosphorylation of dGMP and dTMP to dGDP and dTDP, respectively, by using either GTP, dGTP or dTTP as the phosphate donor. Either form of gp1.7 exhibit identical kinase activity as compared with wild‐type gp1.7 that contains a mixture of both forms. The K_m of 70 µM and Kcat of 4.3 s^?1 for dTMP are similar to those found for E. coli thymidylate kinase. However, unlike the host enzyme, gp1.7 efficiently catalyses the conversion of the chain‐terminating dideoxythymidylate (ddTMP) to ddTDP. This finding explains the sensitivity of phage T7 but not E. coli to exogenous ddT. Gp1.7 is unusual in that it has no sequence homology to any known nucleotide kinase, it has no identifiable nucleotide‐binding motif and its activity is independent of added metal ions. When coupled with nucleoside diphosphate kinase, gp1.7 exponentially converts dTMP to dTTP.     

Administration of vitamin E attenuates airway inflammation through restoration of Nrf2 in a mouse model of asthma

Accumulating evidence reveals that ROS is one of the key mediators that contribute to the development of asthma. Studies on antioxidants have shown to have beneficial effects on asthma management. However, we still do not know the precise mechanism, and the effects depend on age. This study was conducted to assess the levels of ROS and the effect of antioxidants in younger and older mice using an eosinophilic asthma model. We analyzed airway hyperresponsiveness (AHR), cytokines in bronchoalveolar lavage fluid (BALF), inflammatory cell counts, and the expression levels of NFκB, Nrf2, EPx, and EDN in the lung tissue, as well as the level of ROS in the lung tissue and BALF. The degree of eosinophilia and the levels of IL-5, ROS, and NFκB were significantly increased, whereas the endogenous levels of vitamin E and Nrf2 were decreased in the lung and BALF in the older mice compared to younger mice. The administration of vitamin E attenuated AHR, airway inflammation, and the level of IL-13 and ROS and enhanced the Nrf2 level in the older mice compared to the younger mice. Taken together, vitamin E treatment may have the therapeutic potential through restoration of the Nrf2 level, especially in elderly asthma.