Design,synthesis, X-ray studies,and biological evaluation of novel BACE1 inhibitors with bicyclic isoxazoline carboxamides as the P3 ligand

We describe the design, synthesis, X-ray studies, and biological evaluation of novel BACE1 inhibitors containing bicyclic isoxazoline carboxamides as the P3 ligand in combination with methyl cysteine, methylsulfonylalanine and Boc-amino alanine as P2 ligands. Inhibitor 3a displayed a BACE1 K_i value of 10.9?nM and EC₅₀ of 343?nM. The X-ray structure of 3a bound to the active site of BACE1 was determined at 2.85?Å resolution. The structure revealed that the major molecular interactions between BACE1 and the bicyclic tetrahydrofuranyl isoxazoline heterocycle are van der Waals in nature.     

An Essential Role for ECSIT in Mitochondrial Complex I Assembly and Mitophagy in Macrophages

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Analysis of tail-anchored protein translocation pathway in plants

Tail-anchored (TA) proteins are a special class of membrane proteins that carry out vital functions in all living cells. Targeting mechanisms of TA proteins are investigated as the best example for post-translational protein targeting in yeast. Of the several mechanisms, Guided Entry of Tail-anchored protein (GET) pathway plays a major role in TA protein targeting. Many in silico and in vivo analyses are geared to identify TA proteins and their targeting mechanisms in different systems including Arabidopsis thaliana. Yet, crop plants that grow in specific and/or different conditions are not investigated for the presence of TA proteins and GET pathway. This study majorly investigates GET pathway in two crop plants, Oryza sativa subsp. Indica and Solanum tuberosum, through detailed in silico analysis. 508 and 912 TA proteins are identified in Oryza sativa subsp. Indica and Solanum tuberosum respectively and their localization with respect to endoplasmic reticulum (ER), mitochondria, and chloroplast has been delineated. Similarly, the associated GET proteins are identified (Get1, Get3 and Get4) and their structural inferences are elucidated using homology modelling. Get3 models are based on yeast Get3. The cytoplasmic Get3 from O. sativa is identified to be very similar to yeast Get3 with conserved P-loop and TA binding groove. Three cytoplasmic Get3s are identified for S. tuberosum. Taken together, this is the first study to identify TA proteins and GET components in Oryza sativa subsp. Indica and Solanum tuberosum, forming the basis for any further experimental characterization of TA targeting and GET pathway mechanisms in crop plants.     

In Vivo Photomodification of Ribulose-1,5-Bisphosphate Carboxylase/Oxygenase Holoenzyme by Ultraviolet-B Radiation (Formation of a 66-Kilodalton Variant of the Large Subunit)

Increased levels of solar ultraviolet (290-320 nm) (UV-B) radiation could have profound effects on plant proteins because the aromatic amino acids in proteins absorb strongly in this spectral region. We have investigated the effects of UV-B radiation on plant proteins and have observed a novel 66-kD protein. This product was formed in vivo when Brassica napus L. plants grown for 21 d in 65 [mu]mol m-2 s-1 photosynthetically active radiation were subsequently exposed to 65 [mu]mol m-2 s-1 photosynthetically active radiation plus UV-B radiation (1.5 [mu]mol m-2 s-1). The protein appeared after 4 h of UV-B irradiation and accumulated during the next 16 h in UV-B. The 66-kD protein cross-reacted with an antiserum against the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) holoenzyme. Analysis of soluble leaf proteins revealed that the 66-kD product had a number of isoforms corresponding closely to those of the large subunit of Rubisco (LSU). Partial proteolytic digests of the LSU and the 66-kD protein resulted in an equivalent pattern of protein fragments, leading to the conclusion that the 66-kD protein was a photomodified form of the LSU. A similar high molecular mass variant of Rubisco was observed in soluble protein extracts from leaves of tomato (Lycopersicon esculentum), tobacco (Nicotiana tabacum), and pea (Pisum sativum L.) plants treated in vivo with UV-B, suggesting that it might be a common product, at least among C3 plants. It is interesting that the 66-kD product appears to be generated after incorporation of the LSU into holoenzyme complexes. This conclusion was drawn from two lines of evidence. First, the LSU variant co-purified with holoenzyme complexes isolated by nondenaturing polyacrylamide gel electrophoresis. Second, a UV-B-specific 66-kD protein did not accumulate in a tobacco mutant that synthesizes the Rubisco subunits but does not assemble them into normal holoenzyme complexes.     

Structural motifs for pyridoxal-5'-phosphate binding in decarboxylases: an analysis based on the crystal structure of the Lactobacillus 30a ornithine decarboxylase.

Two of the five domains in the structure of the ornithine decarboxylase (OrnDC) from Lactobacillus 30a share similar structural folds around the pyridoxal-5''-phosphate (PLP)-binding pocket with the aspartate aminotransferases (AspATs). Sequence comparisons focusing on conserved residues of the aligned structures reveal that this structural motif is also present in a number of other PLP-dependent enzymes including the histidine, dopa, tryptophan, glutamate, and glycine decarboxylases as well as tryptophanase and serine-hydroxymethyl transferase. However, this motif is not present in eukaryotic OrnDCs, the diaminopimelate decarboxylases, nor the Escherichia coli or oat arginine decarboxylases. The identification and comparison of residues involved in defining the different classes are discussed.     

Fas activates NF-kappaB and induces apoptosis in T-cell lines by signaling pathways distinct from those induced by TNF-alpha

The p55 tumor necrosis factor (TNF) receptor and the Fas (CD95/APO-1) receptor share an intracellular domain necessary to induce apoptosis, suggesting they utilize common signaling pathways. To define pathways triggered by Fas and TNF-alpha we utilized human CEM-C7 T-cells. As expected, stimulation of either receptor induced apoptosis and TNF-alpha-induced signaling included the activation of NF-kappaB. Surprisingly, Fas-induced signaling also triggered the activation of NF-kappaB in T cells, yet the kinetics of NF-kappaB induction by Fas was markedly delayed. NF-kappaB activation by both pathways was persistent and due to the sequential degradation of IkappaB-alpha and IkappaB-beta. However, the kinetics of IkappaB degradation were different and there were differential effects of protease inhibitors and antioxidants on NF-kappaB activation. Signaling pathways leading to activation of apoptosis were similarly separable and were also independent of NF-kappaB activation. Thus, the Fas and TNF receptors utilize distinct signal transduction pathways in T-cells to induce NF-kappaB and apoptosis.     

Role of DNA barcoding in marine biodiversity assessment and conservation: An update

More than two third area of our planet is covered by oceans and assessment of marine biodiversity is a challenging task. With the increasing global population, there is a tendency to exploit marine resources for food, energy and other requirements. This puts pressure on the fragile marine environment and necessitates sustainable conservation efforts. Marine species identification using traditional taxonomical methods is often burdened with taxonomic controversies. Here we discuss the comparatively new concept of DNA barcoding and its significance in marine perspective. This molecular technique can be useful in the assessment of cryptic species which is widespread in marine environment and linking the different life cycle stages to the adult which is difficult to accomplish in the marine ecosystem. Other advantages of DNA barcoding include authentication and safety assessment of seafood, wildlife forensics, conservation genetics and detection of invasive alien species (IAS). Global DNA barcoding efforts in the marine habitat include MarBOL, CeDAMar, CMarZ, SHARK-BOL, etc. An overview on DNA barcoding of different marine groups ranging from the microbes to mammals is revealed. In conjugation with newer and faster techniques like high-throughput sequencing, DNA barcoding can serve as an effective modern tool in marine biodiversity assessment and conservation.