Comparing interfacial dynamics in protein-protein complexes: an elastic network approach

Background  

The transient, or permanent, association of proteins to form organized complexes is one of the most common mechanisms of regulation of biological processes. Systematic physico-chemical studies of the binding interfaces have previously shown that a key mechanism for the formation/stabilization of dimers is the steric and chemical complementarity of the two semi-interfaces. The role of the fluctuation dynamics at the interface of the interacting subunits, although expectedly important, proved more elusive to characterize. The aim of the present computational study is to gain insight into salient dynamics-based aspects of protein-protein interfaces.     

Antioxidant responses in Phanerochaete chrysosporium exposed to Astrazone Red FBL textile dye

Interest in environmental‐pollutant‐induced oxidative stress and knowledge of the interactions between reactive oxygen species and cellular systems have increased in toxicology and microbial ecology considerably in recent decades. These reactive oxidants are produced by a variety of environmental sources: ionizing radiations, ultraviolet light, redox cycling drugs, hyperoxia, ischemia and redox‐active xenobiotics or during metabolism of environmental pollutants, such as heavy metals in mining industries, dyes in wastewater of textile industries, pesticides and polycyclic hydrocarbons, i.e. foreign materials. In this study, the effect of dye on the antioxidative defence system of Phanerochaete chrysosporium was investigated, and we showed the ability of Phanerochaete chrysosporium to antioxidative response and defence system exposed to Astrazone Red FBL. Catalase, glutathione reductase, glutathione s‐transferase activities and level of glutathione decreased, depending on the period of growth in each exposure to low and high concentration group (20 and 50 ppm) compared with the control group. Copyright © 2012 John Wiley & Sons, Ltd.     

Chlamydia trachomatis as a cause of abortion

The possible role of C. trachomatis as a causative agent of abortion in humans was investigated using the tissue culture method for the isolation of chlamydia. Two cases of spontaneous abortion and another seven of recurrent abortion due to C. trachomatis were positively identified. Among those with recurrent abortion were four patients with history of second trimester abortion.     

Structural and functional analysis of perforin mutations in association with clinical data of familial hemophagocytic lymphohistiocytosis type 2 (FHL2) patients

Perforin plays a key role in the immune system via pore formation at the target cell membrane in the elimination of virus‐infected and transformed cells. A vast number of observed mutations in perforin impair this mechanism resulting in a rare but fatal disease, familial hemophagocytic lymphohistiocytosis type 2 (FHL2). Here we report a comprehensive in silico structural analysis of a collection of 76 missense perforin mutations based on a proposed pore model. In our model, perforin monomers oligomerize having cyclic symmetry in consistent with previously found experimental constraints yet having flexibility in the size of the pore and the number of monomers involved. Clusters of the mutations on the model map to three distinct functional regions of the perforin. Calculated stability (free energy) changes show that the mutations mainly destabilize the protein structure, interestingly however, A91V polymorphism, leads to a more stable one. Structural characteristics of mutations help explain the severe functional consequences on perforin deficient patients. Our study provides a structural approach to the mutation effects on the perforin oligomerization and impaired cytotoxic function in FHL2 patients.     

Synthesis of alginate‐silica hybrid hydrogel for biocatalytic conversion by β‐glucosidase in microreactor

The organic–inorganic hybrid materials have been used in different fields to immobilize biomolecules since they offer many advantages. The aim of this study was to optimize and characterize the alginate‐silica hybrid hydrogel as a stable and injectable form for microfluidic systems using internal gelation method and increase the stability and activity of immobilized enzyme for biocatalytic conversions as well. Characterization was carried out by scanning electron microscopy, energy dispersive spectroscopy/mapping, Brunauer–Emmett–Teller, Barrett–Joyner–Halenda, and Fourier‐transform infrared spectroscopy analyses, and the shrinkages of monoliths were evaluated. Subsequent to optimizing the enzyme concentration (40 μg), hydrolytic conversion of 4‐nitrophenyl β‐d ‐glucopyranoside (pNPG) was performed to understand the behavior of the bioconversion in the microfluidic system. The yield was 94% which reached the equilibrium at 24 h indicating that the alginate‐silica gel derived microsystem overcome some drawbacks of monolithic systems. Additionally, bioconversion of Ruscus aculeatus saponins was carried out at the same setup in order to obtain aglycon part, which has pharmaceutical significance. Although pure aglycon could not be achieved, an intermediate compound was obtained based on the HPLC analysis. The developed formulation can be utilized for various life science applications.     

Change in termite communities along a chronosequence of mango tree orchards in the north of Côte d’Ivoire

Termites constitute the major component of the macrofauna of the soil, and influence the structure of the soil, in tropical regions. This study aimed to estimate their assemblages in a chronosequence of mango tree orchards in the north of Côte d’Ivoire and compare them with those in unmanaged savanna. Using a standardized method of rapid biodiversity estimation, termites were collected in seven age classes of mango tree orchards (class 1: <5 years; class 2: 5–9 years; class 3: 10–14 years; class 4: 15–19 years; class 5: 20–24 years; class 6: 25–29 years; class 7: 30 years and over) and compared with termites collected from the savanna. Results show that the species richness was lowest in the young orchards of class 1 (9 species), and increased with the age of the orchards to reach its maximum in the old orchards of class 7 (28 species); these latter were comparable in richness with the savanna (26 species). The Shannon index (H’) and the evenness (E) follow the same trend as the species richness. The orchards of classes 1 and 2 were more dissimilar to the savanna. In contrast, termites were well represented in the savanna and in the old orchard of classes 6 and 7. Rhinotermitinae and Cubitermitinae subfamilies, absent in the young orchards of classes 1 and 2, were very abundant in the old orchards (classes 6 and 7). Overall, the findings of this study show that only the old mango orchards sustain termite diversity that comes close to that of the savanna. In this region, the cessation of agricultural activities in mango orchards favors the reconstitution of termite communities and presumably the restoration of the ecosystem services provided by termites. Thus it would be possible to combine agriculture and the conservation soil biodiversity.     

Enzyme immunoassay in the diagnosis of Chlamydia trachomatis infections in diverse patient groups

An enzyme immunoassay (EIA) in parallel with cell culture was used to investigate the extent of infections due to Chlamydia trachomatis. EIA reactive confirmed in cell culture was taken as positive. C. trachomatis was found in 6 (26.0%) of 23 men with symptomatic non-gonococcal urethritis (NGU), ten (17.2%) of 58 symptom-free males and in three of 4 with postgonococcal urethritis. Among 106 asymptomatic pregnant women studied the incidence of C. trachomatis was 8.5% while a higher incidence (16.7%) was found in those with symptoms. C. trachomatis positivity in asymptomatic and symptomatic post-natal screening were 11.4% and 7.7%. Of 43 symptomatic non-pregnant females investigated, 7 (16.3%) were found to be positive for C. trachomatis. Of 3 women with PID, 2 (66.7%) harboured C. trachomatis in their cervix while in another 29 infertile women, C. trachomatis was positive in 3 (8.1%). Contraceptives appeared to have an effect on the chlamydial positivity. Comparative testing of EIA with the standard cell culture method in this study indicate EIA as a suitable alternative for the definitive diagnosis of chlamydial infection in high prevalence settings and with caution in low prevalence settings.