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Y Beck

Publications and source records attributed to Y Beck.

49 records · Page 3Linked to original sources
PubMed1990

A constitutive expression vector system driven by the deo P1P2 promoters of Escherichia coli.

The P1P2 promoters of Escherichia coli K12 deo operon, residing on an AvaII restriction fragment, were used to construct a new expression vector. To evaluate the potential of the P1P2-driven expression system we have inserted the sequence of human superoxide dismutase (hSOD) downstream of the deo ribosome binding site. Expression of hSOD was evaluated by means of sodium dodecyl sulphate-polyacrylamide gel electrophoresis and enzyme activity. In crude cell extracts hSOD expression levels were found to be high in hosts possessing no deoR or cytR repressors. Highest levels of hSOD expression were obtained with a high-copy-number plasmid regardless of the host used. Expressed hSOD can account for 35%-40% of total protein in E. coli.

Escherichia coli↗
PubMed1982

In vitro-constructed RP4-prime plasmids mediate orientated mobilization of the Proteus morganii chromosome.

RP4-prime plasmids containing inserts of Proteus morganii strain 2815 chromosomal DNA (0.5-13 megadaltons in size) were constructed in vitro. When introduced into the latter organism, the hybrid plasmids promoted transfer of chromosomal markers in an orientated manner, with recombinant frequencies from 10(-4) to 10(-6) per donor. Transconjugants expressed the tetracycline-resistant phenotype of the plasmids. Plasmid-guided trajectories overlapped and a circular map of chromosome markers was constructed. Correspondence between size of inserted chromosomal DNA in hybrid plasmids and numbers of markers transferred suggested that homology played a role in chromosome mobilization by these plasmids.

Chromosome Mapping↗
PubMed1980

Mobilization of the Proteus morganii chromosome by R plasmids.

R plasmids R702, R711b, R1, D, Rip69, R447b, R471 and R394, belonging to different incompatibility groups, mobilized the Proteus morganii 2815 chromosome. Matings employing plasmids R711b or R702 as sex factors with doubly auxotrophic recipients produced recombinants characterized by the obligatory inheritance of ser-1+, irrespective of the selected marker.

Chromosomes, Bacterial↗
PubMed1980

DNA binding properties of simian virus 40 T-antigens synthesized in vivo and in vitro.

Simian virus 40 large T- and small t-antigens have been shown previously to share immunological determinants and common sequences and to have roles in virus-induced cell transformation. However, only large T-antigen is a DNA binding protein. Under all conditions tested, small t-antigen did not interact with DNA. Large T-antigen synthesized in infected cells bound to both native calf thymus and simian virus 40 DNAs. As its binding efficiency was less than 100%, it is likely that there are different forms of T-antigen which vary in their affinity for DNA. Large T-antigen synthesized in cell-free protein-synthesizing systems primed by simian virus 40 mRNA also bound to DNA-cellulose, whereas small t-antigen similarly synthesized in vitro did not. An 82,000-molecular-weight T-antigen polypeptide synthesized in cell-free protein-synthesizing systems primed by simian virus 40 complementary RNA transcribed in vitro from simian virus 40 DNA by Escherichia coli RNA polymerase bound efficiently to simian virus 40 DNA. As this product did not share sequences with the small t-antigen, it can be concluded that the amino-terminal portion of the T-antigen is not required for some of its specific DNA binding properties.

Antigens, Neoplasm↗
PubMedDate not supplied

Molecular cloning of Proteus morganii phenylalanine deaminase gene in Escherichia coli.

The gene for phenylalanine deaminase (PAD) of Proteus morganii strain 2815 has been isolated on a 6.3-kb HindIII restriction fragment and cloned within RP4-prime plasmids, pYB2321 and pYB2322, in both orientations. Expression of the cloned gene in Escherichia coli strains was comparable to that in P. morganii 2815. The hybrid plasmids mobilized the 2815 chromosome with trajectories in reverse directions from an origin between ser-2 and ade-1, suggesting the map location of the PAD gene.

Amino Acid Oxidoreductases↗
PubMedDate not supplied

Intrathymic inoculation of donor HLA class I-derived peptide generates donor-specific CD4+CD25+ regulatory T cells.

CD4(+)CD25(+) regulatory T cells are selected in the thymus to control autoreactive thymic escapees preventing autoimmunity that cannot be achieved by negative selection or deletion alone, thus playing an important role in the maintenance of immunological homeostasis. Not only significant in preventing autoimmunity, CD4(+)CD25(+) regulatory T cells have also been shown to be involved in allograft tolerance in organ transplantation. We have formerly introduced two lines of HLA class I transgenic mice to elucidate the role of HLA class I molecules in transplantation biology. Using a heterotopic cardiac transplantation model, we show herein that intrathymic inoculation of donor HLA class I-derived synthetic peptide results in the generation of CD4(+)CD25(+) regulatory T cells, which induce graft specific tolerance without any preconditioning of the recipient or use of immunosuppressive drugs. This study provides evidence of the novel therapeutic potential of CD4(+)CD25(+) regulatory T cells for clinical transplantation.

Amino Acid Sequence↗