Modulation of different forms of glutamine synthetases inRhizobium phaseoli and their possible role in nitrogen fixation

The effect of a number of compounds structurally related to glutamic acid and other nitrogenous compounds on the composition of three forms of glutamine synthetase (GS) inRhizobium phaseoli has been examined in detail. Amino acids like glutamic acid, glutamine, and a fixed source of nitrogen like ammonium chloride did not alter the relative glutamine synthetase composition.l-Methioninedl-sulfoximine (MSX), a glutamate analogue, significantly repressed the synthesis of GSIII to a greater extent.,N-oxalyl,-diaminopropionic acid (ODAP), another glutamate analogue, selectively stimulated the synthesis of GSII, and the effect of ODAP on GSII synthesis was greatly enhanced in the presence of ethylenediamine or ammonium chloride. Ethylenediamine itself caused a predominant synthesis of GSIII.-Cyanoalanine-grownR. phaseoli did not synthesize GSI. The synthesis of the three different glutamine synthetases can thus be differentially modulated.     

Identification and characterization of three forms of glutamine synthetase unique to Rhizobia

Glutamine synthetase (GS) activities of Rhizobia were chromatographically resolved into three distinct forms, GSI, GSII, and GSIII on DEAE cellulose, being eluted with 0.3M, 0.5M and 0.8M KCl, respectively. GSIII was the major form inR. leguminosarum andR. phaseoli. InR. meliloti, however, GSI was the major form. The three forms of GS were also distinguished on the basis of (a) rapid heat inactivation of GSII, (b) insensitivity of GSI to inhibitors, (c) marked inhibition of GSII by thymidine, and (d) inability of Zn⁺⁺ to inhibit GSIII. The three forms of GS are also distinct molecular entities and are unique to Rhizobia.     

Draft genome sequencing and functional annotation and characterization of biofilm-producing bacterium Bacillus novalis PD1 isolated from rhizospheric soil

Antonie van Leeuwenhoek - Biofilm forming bacterium Bacillus novalis PD1 was isolated from the rhizospheric soil of a paddy field. B. novalis PD1 is a Gram-positive, facultatively anaerobic,...     

Introduction of histidine units using benzotriazolide activation

N^α‐Boc‐N^im‐(4‐toluenesulfonyl‐l ‐histidylbenzotriazole) enables convenient acylation of N‐, O‐, S‐, and C‐nucleophiles with no detectable racemization. We report efficient syntheses of novel histidine‐containing di‐, tri‐, and tetra‐peptides and models for the preparation of potentially biologically active histidine N‐, O‐, S‐, and C‐conjugates. Copyright © 2013 European Peptide Society and John Wiley & Sons, Ltd.     

The effect of pH dependence of antibody-antigen interactions on subcellular trafficking dynamics

A drawback of targeting soluble antigens such as cytokines or toxins with long-lived antibodies is that such antibodies can prolong the half-life of the target antigen by a “buffering” effect. This has motivated the design of antibodies that bind to target with higher affinity at near neutral pH relative to acidic endosomal pH (~pH 6.0). Such antibodies are expected to release antigen within endosomes following uptake into cells, whereas antibody will be recycled and exocytosed in FcRn-expressing cells. To understand how the pH dependence of antibody-antigen interactions affects intracellular trafficking, we generated three antibodies that bind IL-6 with different pH dependencies in the range pH 6.0–7.4. The behavior of antigen in the presence of these antibodies has been characterized using a combination of fixed and live cell fluorescence microscopy. As the affinity of the antibody:IL-6 interaction at pH 6.0 decreases, an increasing amount of antigen dissociates from FcRn-bound antibody in early and late endosomes, and then enters lysosomes. Segregation of antibody and FcRn from endosomes in tubulovesicular transport carriers (TCs) into the recycling pathway can also be observed in live cells, and the extent of IL-6 association with TCs correlates with increasing affinity of the antibody:IL-6 interaction at acidic pH. These analyses result in an understanding, in spatiotemporal terms, of the effect of pH dependence of antibody-antigen interactions on subcellular trafficking and inform the design of antibodies with optimized binding properties for antigen elimination.     

Comparative study of mycelia growth and sporophore yield of Auricularia polytricha (Mont.) Sacc on selected palm oil wastes as fruiting substrate

The potential for using agricultural and industrial by-products as substrate for the production of the edible mushroom, Auricularia polytricha, was evaluated using several formulations of selected palm oil wastes mixed with sawdust and further supplemented with selected nitrogen sources. The best substrate formulations were sawdust (SD) mixed with oil palm frond (OPF; 90:10) added with 15 % spent grain (SG) and sawdust mixed with empty fruit bunch (EFB; 50:50) added with 10 % spent grain (SG) with mycelia growth rate of 8 mm/day and 7 mm/day respectively. These two substrate formulations were then subjected to different moisture content levels (65 %, 75 % and 85 %). Highest total fresh sporophore yield at 0.43 % was obtained on SD?+?OPF (90:10)?+?15 % SG at 85 % moisture content, followed closely by SD?+?EFB (50:50)?+?10 % SG with 0.40 % total yield, also at 85 % moisture content. Each of the substrate formulations at 85 % moisture content gave the highest biological efficiency (BE) at 288.9 % and 260.7 %, respectively. Both yield and biological efficiency of A. polytricha on these two formulations were almost three times higher when compared to sawdust substrate alone, thus proving the potential of these formulations to improve yield of this mushroom.