Large‐scale survey and database of high affinity ligands for peptide recognition modules

Many proteins involved in signal transduction contain peptide recognition modules (PRMs) that recognize short linear motifs (SLiMs) within their interaction partners. Here, we used large‐scale peptide‐phage display methods to derive optimal ligands for 163 unique PRMs representing 79 distinct structural families. We combined the new data with previous data that we collected for the large SH3, PDZ, and WW domain families to assemble a database containing 7,984 unique peptide ligands for 500 PRMs representing 82 structural families. For 74 PRMs, we acquired enough new data to map the specificity profiles in detail and derived position weight matrices and binding specificity logos based on multiple peptide ligands. These analyses showed that optimal peptide ligands resembled peptides observed in existing structures of PRM‐ligand complexes, indicating that a large majority of the phage‐derived peptides are likely to target natural peptide‐binding sites and could thus act as inhibitors of natural protein–protein interactions. The complete dataset has been assembled in an online database (http://www.prm‐db.org) that will enable many structural, functional, and biological studies of PRMs and SLiMs.     

Antimicrobial agents from higher plants: Prenylated flavonoids and other phenols from Glycyrrhiza lepidota

Bioassay directed fractionation of extracts of American licorice, Glycyrrhiza lepidota (Leguminosae), resulted in identification of the known bibenzyl, 3,5-dihydroxy-4-(3-methyl-2-butenyl)-bibenzyl, and the known flavanones, glabranin and pinocembrin, as well as the isolation and structure determination of the new flavonol, glepidotin A and the new dihydroflavonol, glepidotin B as antimicrobial agents.     

Recent advances in production,purification and applications of phycobiliproteins

An obligatory sunlight requirement for photosynthesis has exposed cyanobacteria to different quantity and quality of light. Cyanobacteria can exhibit efficient photosynthesis over broad region(450 to 650 nm) of solar spectrum with the help of brilliantly coloured pigment proteins called phycobiliproteins(PBPs). Besides light-harvesting, PBPs are found to involve in several life sustaining phenomena including photoprotection in cyanobacteria. The unique spectral features(like strong absorbance and fluorescence), proteineous nature and, some imperative properties like hepato-protective, antioxidants, anti-inflammatory and anti-aging activity of PBPs enable their use in food, cosmetics, pharmaceutical and biomedical industries. PBPs have been also noted to show beneficial effect in therapeutics of some disease like Alzheimer and cancer. Such large range of applications increases the demand of PBPs in commodity market. Therefore, the large-scale and coast effective production of PBPs is the real need of time. To fulfil this need, many researchers have been working to find the potential producer of PBPs for the production and purification of PBPs. Results of these efforts have caused the inventions of some novel techniques like mixotrophic and heterotrophic strategies for production and aqueous two phase separation for purification purpose. Overall, the present review summarises the recent findings and identifies gaps in the field of production, purification and applications of this biological and economically important proteins.     

Proteolytic fragments of fibronectin function as matrikines driving the chemotactic affinity of prostate cancer cells to human bone marrow mesenchymal stromal cells via the α5β1 integrin

The haematopoietic niche is contributed to by bone marrow-resident mesenchymal stromal cells (BM-MSCs) and subverted by prostate cancer cells. To study mechanisms by which BM-MSCs and prostate cancer cells may interact, we assessed the migration, invasion, adhesion and proliferation of bone-derived prostate cancer cells (PC-3) in co-culture with pluripotent human BM-MSCs. We observed a strong adhesive, migratory and invasive phenotype of PC-3 cells with BM- MSC-co-culture and set out to isolate and characterize the bioactive principle. Initial studies indicated that chemotaxis was secondary to a protein residing in the >100kDa fraction. Size-exclusion chromatography (SEC) recovered peak activity in a high-molecular weight fraction containing thrombospondin-1 (TSP1). While TSP1 immunodepletion decreased activity, put-back with purified TSP1 did not reproduce bioactivity. Further purification of the TSP1-containing high-molecular weight fraction of the BM-MSC secretome with heparin-affinity chromatography recovered bioactivity with highly restricted bands on polyacrylamide gel electrophoresis, determined by mass spectroscopy to be proteolytic fragments of fibronectin (FN). Put-back experiments with full-length FN permitted adhesion but failed to induce migration. Monospecific antibodies to FN blocked adhesion. Proteolytic cleavage of FN generated FN fragments which now induced migration. Neutralizing monoclonal antibodies to FN receptors α5 and β1 integrins, and α5 knockdown specifically blocked migration and adhesion. Conclusion: Fibronectin fragments (FNFr) function as matrikines driving the chemotactic affinity of prostate cancer cells via the α5β1 integrin. Taken together with the high-frequency of α5β1 expression in disseminated prostate cancer cells in bone marrow aspirates from patients, the FNFr/FN-α5β1 interaction warrants further study as a therapeutic target.     

A chlorinated monoterpene ketone, acylated beta-sitosterol glycosides and a flavanone glycoside from Mentha longifolia (Lamiaceae)

Mentha longifolia (Lamiaceae), an aromatic herb yielded a new halogenated chloro-derivative of menthone (longifone), two new derivatives of beta-sitosterol glycoside (longiside-A and -B) and a new flavanone-glycoside (longitin). The beta-sitosterol and flavanone glycosides were purified as their acetate derivatives. Structures of all the isolated constituents were elucidated with the aid of HMBC techniques. However, the structure of longifone was also determined through X-ray crystallography.     

A Peninsular Structure Coordinates Asynchronous Differentiation with Morphogenesis to Generate Pancreatic Islets

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Purification and characterization of Enterobacter sakazakii enterotoxin

Enterobacter sakazakii has recently been recognized as an often fatal neonatal pathogen that rarely infects adults. Although not much is known about factors involved in its pathogenicity, the organism has been reported to produce enterotoxin. Currently, no information is available in the literature about the production and characterization of the enterotoxin. This report is the first attempt regarding purification and biochemical characterization of the enterotoxin produced from E. sakazakii. The toxin was purified by ammonium sulfate precipitation, followed by DEAE cellulose ion exchange and desalting by Sephadex G-100. The 66 kDa toxin was most active at pH 6 and was stable at 90 degrees C for 30 min. This stability combined with the potent activity of the toxin (LD50 = 56 pg) emphasizes the potential risk to neonates fed infant milk formula contaminated with E. sakazakii. Further detailed molecular biological studies on the toxin are warranted in view of its stability and activity.