Shutoff of host transcription triggers a toxin-antitoxin system to cleave phage RNA and abort infection

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Electrostatic map of T7 DNA: comparative analysis of functional and electrostatic properties of T7 RNA polymerase-specific promoters

The entire T7 bacteriophage genome contains 39937 base pairs (Database NCBI RefSeq N1001604). Here, electrostatic potential distribution around double helical T7 DNA was calculated by Coulomb method using the computer program of Sorokin A.A. (lptolik@gmail.com). Electrostatic profiles of 17 promoters recognized by T7 phage-specific RNA polymerase were analyzed. It was shown that electrostatic profiles of all T7 RNA polymerase-specific promoters can be characterized by distinctive motifs which are specific for each promoter class. Comparative analysis of electrostatic profiles of native T7 promoters of different classes demonstrates that T7 RNA polymerase can differentiate them due to their electrostatic features.     

Phage display screening of TIGIT-specific antibody for antitumor immunotherapy

ABSTRACT

The fully synthetic humanized phage antibody library has the advantages including the minimized immunogenicity, which frequently happened in hybridoma cell-based antibody production. In this paper, using the constructed diverse complementarity determining region gene library and the germline gene as the backbone, we constructed eight single-chain antibody libraries and a combinatorial antibody library with a big capacity of 1.41 × 10¹⁰. M13EEA helper phage that was engineered from M13KO7 was applied to prepare phage antibody library. The eukaryotic expression of T-cell immune receptor with Ig and ITIM domain (TIGIT) antigen was used as a target antigen for screening. The screening of antigen-specific single-chain Fc-fused protein was performed through evaluation of binding affinity based on ELISA analysis. The IgG antibody was prepared with the screened single-chain protein. Finally, the CB3 antibody was screened out which exhibits the highest binding affinity with TIGIT with the K_d value of 8.155 × 10^?10 M.     

Identification of novel peptide antagonists for GPIIb/IIIa from a conformationally constrained phage peptide library.

Methods have recently been developed to present vast libraries of random peptides on the surface of filamentous phage. To introduce a degree of conformational constraint into random peptides, a library of hexapeptides flanked by cysteine residues (capable of forming cyclic disulfides) was constructed. This library was screened using the platelet glycoprotein, IIb/IIIa, which mediates the aggregation of platelets through binding of fibrinogen. A variety of peptides containing the sequence Arg-Gly-Asp or Lys-Gly-Asp were discovered and synthesized. The cyclic, disulfide-bonded forms of the peptides bound IIb/IIIa with dissociation constants in the nanomolar range, while reduced forms or an analogue in which Ser replaced the Cys residues bound considerably less tightly. These results demonstrate the feasibility for introducing conformational constraints into random peptide libraries and also demonstrates the potential for using phage peptide libraries to discover pharmacologically active lead compounds.     

Some Analytical Observations of Autoxidation Products of Linoleic Acid and Their Thiobarbituric Acid Reactive Substances

Autoxidation products of linoleic acid (LA) were analyzed, when the weight became 1.14-fold under the autoxidation conditions of satisfactory atmospheric oxygen, at 37°C, in the dark, for 7 days. The LA absorbed 2.8 mol of oxygen to form secondary degradation products. This autoxidized LA consisted of 45% intact substance, 22% a mixture of polymers and endoperoxides, 18% LA hydroperoxides, 3% polar products, 1.7% azelaldehydeic acid, 1.3% hexahal, 0.9% azelaic acid, 0.6% octanoic acid, 0.3% suberaldehydeic acid, and so on. Thus, unstable 2,4-dienoic carbonyls were the main intermediate products of autoxidation of LA. Therefore, malonaldehyde was not a main product nor a major thiobarbituric acid reactive substance.     

Massive expansion of human gut bacteriophage diversity

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Alterations in the cell envelope of Escherichia coli late in bacteriophage T4 infection

The cell envelope of Escherichia coli was examined for changes during late stages of bacteriophage T4 infection. Late events in T4 infection are shown to result in (i) a reduction in the effectiveness of membrane separation procedures employing either isopycnic sucrose gradient centrifugation or selective solubilization of inner membrane by detergent (Sarkosyl or Triton X-100), (ii) the appearance of a 54 000 dalton host protein in membrane preparations, (iii) the adventitious presence of detergent-resistant phage morphogenetic structures in membrane preparations, and (iv) a decrease in the activity of NADH oxidase and an apparent alteration in its association with inner membrane. These modifications occur regardless of the state of the $\text{e}$ and $\text{t}$ genes of T4.