Resurrection of a functional phosphatidylinositol transfer protein from a pseudo-Sec14 scaffold by directed evolution

Sec14-superfamily proteins integrate the lipid metabolome with phosphoinositide synthesis and signaling via primed presentation of phosphatidylinositol (PtdIns) to PtdIns kinases. Sec14 action as a PtdIns-presentation scaffold requires heterotypic exchange of phosphatidylcholine (PtdCho) for PtdIns, or vice versa, in a poorly understood progression of regulated conformational transitions. We identify mutations that confer Sec14-like activities to a functionally inert pseudo-Sec14 (Sfh1), which seemingly conserves all of the structural requirements for Sec14 function. Unexpectedly, the "activation" phenotype results from alteration of residues conserved between Sfh1 and Sec14. Using biochemical and biophysical, structural, and computational approaches, we find the activation mechanism reconfigures atomic interactions between amino acid side chains and internal water in an unusual hydrophilic microenvironment within the hydrophobic Sfh1 ligand-binding cavity. These altered dynamics reconstitute a functional "gating module" that propagates conformational energy from within the hydrophobic pocket to the helical unit that gates pocket access. The net effect is enhanced rates of phospholipid-cycling into and out of the Sfh1* hydrophobic pocket. Taken together, the directed evolution approach reveals an unexpectedly flexible functional engineering of a Sec14-like PtdIns transfer protein-an engineering invisible to standard bioinformatic, crystallographic, and rational mutagenesis approaches.     

Carcass traits of different marketable sizes of rohu,Labeo rohita (Hamilton, 1822)

The present study was carried out to investigate the carcass traits of farmed freshwater Labeo rohita in relation to body size as important information to calculate yield and/or support for machine/manual processing. For this purpose ninety specimens were collected for nine weight groups from 600 to 1100 g, each group with a 100 g increment. Specimens were collected from grow‐out culture ponds of the Central Institute of Freshwater Aquaculture (CIFA), Bhubaneswar. The carcass evaluation technique was followed to evaluate carcass yield, offal yield and carcass cutability. Head size percentage of rohu increased as the body mass increased, which in turn increased the processing yield. Dry matter and ether extract percentage also increased with the body mass; however, moisture percentage showed a decreasing trend. The fore cut showed a distinctly higher ether extract percentage followed by the middle and posterior cuts. There was a good correlation development to describe the relationship between yield traits and body weight.     

The MHC class II-associated invariant chain interacts with the neonatal Fc gamma receptor and modulates its trafficking to endosomal/lysosomal compartments

The neonatal Fc receptor for IgG (FcRn) transfers maternal IgG to the offspring and protects IgG from degradation. The FcRn resides in an acidic intracellular compartment, allowing it to bind IgG. In this study, we found the association of FcRn and invariant chain (Ii). The interaction was initiated within the endoplasmic reticulum by Ii binding to either the FcRn H chain alone or FcRn H chain-beta(2)-microglobulin complex and appeared to be maintained throughout the endocytic pathway. The CLIP in Ii was not required for FcRn-Ii association. The interaction was also detected in IFN-gamma-treated THP-1, epithelial and endothelial cells, and immature mouse DCs. A truncated FcRn without the cytoplasmic tail was unable to traffic to early endosomes; however, its location in early endosomes was restored by Ii expression. FcRn was also detected in the late endosome/lysosome only in the presence of Ii or on exposure to IFN-gamma. In immature human or mouse DCs, FcRn was barely detected in the late endosome/lysosome in the absence of Ii. Furthermore, the cytoplasmic tail of Ii conferred tailless FcRn to route to both the early endosome and late endosome/lysosome in a hybrid molecule. Because the FcRn is expressed in macrophages and DCs or epithelial and endothelial cells where Ii is induced under inflammation and infection, these results reveal the complexity of FcRn trafficking in which Ii is capable of expanding the boundary of FcRn trafficking. Taken together, the intracellular trafficking of FcRn is regulated by its intrinsic sorting information and/or an interaction with Ii chain.     

Evaluation of anti-inflammatory activity of plant lipids containing alpha-linolenic acid

Two groups of fatty acids are essential to the body, the omega6 (n6) series derived from linoleic acid (18:2, n-6) and the omega3 (n3) series derived from alpha-linolenic acid (18:3, n-3). Fatty acids provide energy, are an integral part of the cell membranes and are precursors of prostaglandins, thromboxanes and leukotrienes collectively known as eicosanoids. Eicosanoids participate in development and synthesis of immunological and inflammatory responses. The fixed oils (1, 2, 3 ml/kg) containing alpha-linolenic acid, obtained from the seeds of Linseed (Linum usitatissimum), Soyabean (Glycine max) and Holy basil (Ocimum sanctum) were screened for their antiinflammatory activity using carrageenan, leukotriene and arachidonic acid induced paw edema models in rats and the antiinflammatory effects were compared with the standard drug indomethacin. Significant inhibition of paw edema was produced by all the oils in the highest dose (3 ml/kg) in all the models. While O. sanctum oil produced the maximum percentage inhibition in leukotriene induced paw edema, L. usitatissimum oil produced maximum percentage inhibition in carrageenan and arachidonic acid induced paw edema models. The results show that oils with higher alpha-linolenic acid content (L. usitatissimum and O. sanctum) produced a greater inhibition of paw edema suggesting that modulation of the course of inflammatory disorders may be achieved by altering the eicosanoid precursor (i.e. poly unsaturated fatty acids: PUFA) availability through dietary manipulation.     

Indigenous Plants Demonstrating Effective Antioxidant Properties

Biology Bulletin - Increased production of antioxidant herbal supplements utilizing traditional medicinal plants has been attributed to a high margin of economic effectiveness, environmental...     

Crystal structure of vaccinia virus uracil-DNA glycosylase reveals dimeric assembly

Background  

Uracil-DNA glycosylases (UDGs) catalyze excision of uracil from DNA. Vaccinia virus, which is the prototype of poxviruses, encodes a UDG (vvUDG) that is significantly different from the UDGs of other organisms in primary, secondary and tertiary structure and characteristic motifs. It adopted a novel catalysis-independent role in DNA replication that involves interaction with a viral protein, A20, to form the processivity factor. UDG:A20 association is essential for assembling of the processive DNA polymerase complex. The structure of the protein must have provisions for such interactions with A20. This paper provides the first glimpse into the structure of a poxvirus UDG.     

Potassium uptake efficiency and dynamics in the rhizosphere of maize (Zea mays L.), wheat (Triticum aestivum L.), and sugar beet (Beta vulgaris L.) evaluated with a mechanistic model

Plant species differ in nutrient uptake efficiency. With a pot experiment, we evaluated potassium (K) uptake efficiency of maize (Zea mays L.), wheat (Triticum aestivum L.), and sugar beet (Beta vulgaris L.) grown on a low-K soil. Sugar beet and wheat maintained higher shoot K concentrations, indicating higher K uptake efficiency. Wheat acquired more K because of a greater root length to shoot dry weight ratio. Sugar beet accumulated more shoot K as a result of a 3- to 4-fold higher K influx as compared to wheat and maize, respectively. Nutrient uptake model NST 3.0 closely predicted K influx when 250 mg K kg^?1 were added to the soil, but under-predicted K influx under low K supply. Sensitivity analysis showed that increasing soil solution K concentration (C_Li) by a factor of 1.6–3.5 or buffer power (b) 10- to 50-fold resulted in 100% prediction of K influx. When both maximum influx (I_max) and b were increased by a factor of 2.5 in maize and wheat and 25 in sugar beet, the model could predict measured K influx 100%. In general, the parameter changes affected mostly calculated K influx of root hairs, demonstrating their possible important role in plant K efficiency.