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  • Springer  (4)
  • Nature Publishing Group  (3)
  • Blackwell Publishing Ltd  (2)
  • Nature America Inc.  (2)
  • 1
    ISSN: 1365-2958
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie , Medizin
    Notizen: We characterized a novel mutant phenotype (tetrapac, tpc) of Neisseria gonorrhoeae (Ngo) associated with a distinctive rough-colony morphology and bacterial growth in clusters of four. This phenotype, suggesting a defect in cell division, was isolated from a mutant library of Ngo MS11 generated with the phoA minitransposon TnMax4. The tpc mutant shows a 30% reduction in the overall murein hydrolase activity using Escherichia coli murein as substrate. Tetrapacs can be resolved by co-cultivation with wild-type Ngo, indicating that Tpc is a diffusible protein. Interestingly, Tpc is absolutely required for the natural transformation competence of piliated Ngo. Mutants in tpc grow normally, but show a ∼ 10-fold reduction in their ability to invade human epithelial cells. The tpc sequence reveals an open reading frame of ∼1 kb encoding a protein (Tpc) of 37kDa. The primary gene product exhibits an N-terminal leader sequence typical of lipoproteins, but palmitoylation of Tpc could not be demonstrated. The ribosomal binding site of tpc is immediately downstream of the translational stop codon of the folC gene coding for an enzyme involved in folic acid biosynthesis and one-carbon metabolism. The tpc gene is probably co-transcribed from the folC promoter and a promoter located within the folC gene. The latter promoter sequence shares significant homology with E. coli gearbox consensus promoters. All three mutant phenotypes, i.e. the cell separation defect, the transformation deficiency and the defect in cell invasion can be restored by complementation of the mutant with an intact tpc gene. To some extent the tcp phenotype is reminiscent of iap in Listeria, lytA in Streptococcus pneumoniae and lyt in Bacillus subtilis, all of which are considered to represent murein hydrolase defects.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 2
    ISSN: 1546-1696
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: [Auszug] We describe the design and detailed characterization of a gas-inducible transgene control system functional in different mammalian cells, mice and prototype biopharmaceutical manufacturing. The acetaldehyde-inducible AlcR-PalcA transactivator-promoter interaction of the Aspergillus nidulans ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 3
    ISSN: 1546-1696
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: [Auszug] Heterologous mammalian gene regulation systems for adjustable expression of multiple transgenes are necessary for advanced human gene therapy and tissue engineering, and for sophisticated in vivo gene-function analyses, drug discovery, and biopharmaceutical manufacturing. The ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature America Inc.
    Nature biotechnology 18 (2000), S. 768-774 
    ISSN: 1546-1696
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: [Auszug] Caspases (cysteine-containing aspartate-specific proteases) are at the core of the cell's suicide machinery. These enzymes, once activated, dismantle the cell by selectively cleaving key proteins after aspartate residues. The events culminating in caspase activation are the subject of intense ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 5
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature America Inc.
    Nature biotechnology 18 (2000), S. 1203-1208 
    ISSN: 1546-1696
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: [Auszug] Here we describe repressible (PipOFF) as well as inducible (PipON) systems for regulated gene expression in mammalian cells, based on the repressor Pip (pristinamycin-induced protein), which is encoded by the streptogramin resistance operon of Streptomyces coelicolor. Expression of genes placed ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Digitale Medien
    Digitale Medien
    [s.l.] : Nature Publishing Group
    Nature biotechnology 22 (2004), S. 867-870 
    ISSN: 1546-1696
    Quelle: Nature Archives 1869 - 2009
    Thema: Biologie , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: [Auszug] In multicellular systems cell identity is imprinted by epigenetic regulation circuits, which determine the global transcriptome of adult cells in a cell phenotype–specific manner. By combining two repressors, which control each other's expression, we have developed a mammalian epigenetic ...
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 7
    Digitale Medien
    Digitale Medien
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 137 (1996), S. 0 
    ISSN: 1574-6968
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Biologie
    Notizen: Abstract We previously identified and genetically characterized several factors essential for the natural competence of transformation in Neisseria gonorrhoeae. Here we analyse the sequential action of these factors and dissect the overall transformation process into three distinct steps, (i) the sequence-specific uptake of transforming DNA into a DNase-resistant state, (ii) the transfer of DNA to the cytosol and (iii) the processing and recombination of the incoming with the resident DNA. While two pilus-associated factors, PilE and PilC, were previously implicated in the early DNA uptake event, we show here that three competence factors unrelated to pilus biogenesis, ComA, ComL and Tpc, are not essential for DNA uptake and rather act in a subsequent step. The respective mutants, however, lack the characteristic nucleolytic processing observed with the incoming DNA in both wild-type and non-transformable RecA-deficient N. gonorrhoeae, indicating that they are blocked in the processing and/or the delivery of DNA to the cytoplasm. A hypothetical model proposing a sequential action of the known gonococcal competence factors is presented.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 8
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 250 (1996), S. 277-285 
    ISSN: 1617-4623
    Schlagwort(e): Key words Gonococcus ; Folic acid ; Dihydrofolate synthetase ; Folylpolyglutamate synthetase ; One-carbon metabolism
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract  The gene coding for folylpoly-(γ)-glutamate synthetase (FPGS)-dihydrofolate synthetase (DHFS) of Neisseria gonorrhoeae (Ngo) has been cloned by functional complementation of an Escherichia coli folC mutant (SF4). The sequence encodes a 224-residue protein of 46.4 kDa. It shows 46% identity to the E. coli FPGS-DHFS and 29% identity to the FPGS of Lactobacillus casei. Sequence comparisons between the three genes reveal regions of high homology, including ATP binding sites required for bifunctionality, all of which may be important for FPGS activity. In contrast to L. casei FPGS, the E. coli and Ngo enzymes share some additional regions which may be essential for DHFS activity. The products of Ngo folC and flanking genes were monitored by T7 promoter expression. Interestingly, deletion of the upstream folI gene, which encodes a 16.5 kDa protein, abolishes the capacity of folC to complement E. coli SF4 to the wild-type phenotype. The ability to complement can be restored by folI provided in trans. Unlike folC mutants, gonococcal folI mutants are viable and display no apparent phenotype. Thus, in contrast to E. coli, Ngo folC is expressed at a sufficiently high level from its own promoter, in the absence of FolI. This study provides the first insights into the genetic complexity of one-carbon metabolism in Ngo.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Cytotechnology 28 (1998), S. 111-126 
    ISSN: 1573-0778
    Schlagwort(e): autoregulation ; cell-cycle engineering ; eukaryotic operon ; IRES ; multigene engineering ; picornavirus ; pTRIDENT ; regulated expression
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract Contemporary basic research is rapidly revealing increasingly complex molecular regulatory networks which are often interconnected via key signal integrators. These connections among regulatory and catalytic networks often frustrate bioengineers as promising metabolic engineering strategies are bypassed by compensatory metabolic responses or cause unexpected, undesired outcomes such as apoptosis, product protein degradation or inappropriate post- translational modification. Therefore, for metabolic engineering to achieve greater success in mammalian cell culture processes and to become important for future applications such as gene therapy and tissue engineering, this technology must be enhanced to allow simultaneous, in cases conditional, reshaping of metabolic pathways to access difficult-to-attain cell states. Recent advances in this new territory of multigene metabolic engineering are intimately linked to the development of multicistronic expression technology which allows the simultaneous, and in some cases, regulated expression of several genes in mammalian cells. Here we review recent achievements in multicistronic expression technology in view of multigene metabolic engineering.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 10
    ISSN: 1573-0778
    Schlagwort(e): CITE ; EMCV ; GFP ; IRES ; picornavirus
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie , Medizin , Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
    Notizen: Abstract Based on internal ribosomal entry sites (IRES) of picornaviral origin we constructed a novel family of mammalian expression vectors. pQuattro vectors contain quattrocistronic artificial eukaryotic operons which link, in a single transcript, the simultaneous and coordinated as well as adjustable expression of up to three independent genes of interest to a terminal neomycin (neo) resistance marker. Due to the strict genetic linkage of the transgenes and the terminal selection marker, this genetic configuration enables, by the selection on neomycin, multigene metabolic engineering of mammalian cells in a single step (one-step metabolic engineering). Furthermore, selection on the terminal cistron of multicistronic expression units enforces cocistronic expression of all upstream encoded genes and maximises genetic integrity of the eukaryotic operon in stable mammalian cell lines, since clones harbouring damaged multicistronic expression units become neomycin-sensitive and are automatically counterselected (auto-selection). The modular set-up and the abundance of restriction sites in pQuattro vectors facilitate the movement of individual genes between multicistronic expression vectors and guarantees high compatibility with genetic elements of a wide variety of existing mammalian expression vectors.
    Materialart: Digitale Medien
    Standort Signatur Einschränkungen Verfügbarkeit
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