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  • 1
    Electronic Resource
    Electronic Resource
    A fibrinogen receptor from group B Streptococcus interacts with fibrinogen by repetitive units with novel ligand binding sites (2002)
    Oxford, UK : Blackwell Science, Ltd
    Molecular microbiology 46 (2002), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Group B Streptococcus (GBS) is a frequent cause of bacterial sepsis and meningitis in neonates. During the course of infection, GBS colonizes and invades a number of host compartments, thereby interacting with different host proteins. In the present report, we describe the isolation of the fbsA gene, which encodes a fibrinogen receptor from GBS. The deduced FbsA protein is characterized by repetitive units, each 16 amino acids in length. Sequencing of the fbsA gene from five different GBS strains revealed significant variation in the number of repeat-encoding units. The deletion of the fbsA gene in the genome of GBS 6313 completely abolished fibrinogen binding, suggesting that FbsA is the major fibrinogen receptor in this strain. Growth of the fbsA deletion mutant in human blood was significantly impaired, indicating that FbsA protects GBS from opsonophagocytosis. In Western blot experiments with truncated FbsA ­proteins, the repeat region of FbsA was identified as mediating fibrinogen binding. Using synthetic peptides, even a single repeat unit of FbsA was demonstrated to bind to fibrinogen. Spot membrane analysis and competitive binding experiments with peptides carrying single amino acid substitutions allowed the prediction of a fibrinogen-binding motif with the consensus sequence G-N/S/T-V-L-A/E/M/Q-R-R-X-K/R/W-A/D/E/N/Q-A/F/I/L/V/Y-X-X-K/R-X-X.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.2002.03177.x
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  • 2
    Electronic Resource
    Electronic Resource
    Functional analysis of a PcsB-deficient mutant of group B streptococcus (2003)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 221 (2003), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Group B streptococcus (GBS) is the major cause of bacterial sepsis and meningitis in neonates and poses a significant threat to parturient women. Recently, we identified in GBS the polypeptide PcsB, which is a protein required for cell separation of GBS, and which is also involved in the antibiotic sensitivity of these bacteria. In the present study, the introduction of the pcsB-carrying plasmid pATpcsB into the PcsB-deficient GBS mutant Sep1 restored the phenotype and the antibiotic susceptibility of this strain to that of the GBS wild-type. Although Northern blots revealed a four- to five-fold increased transcription of pcsB in pATpcsB-carrying GBS strains, overexpression of pcsB did not result in higher amounts of PcsB in the cell wall and in the culture supernatant of GBS, indicating regulatory mechanisms that control the translation or secretion of PcsB in these bacteria. In the culture supernatant of mutant Sep1 significant amounts of enolase were identified. As this protein was also present in extracts of cell wall-bound proteins from the GBS wild-type, it can be speculated that GBS can translocate enolase across the cytoplasmic membrane. Northern blot analysis exhibited similar expression of the enolase gene in the GBS strains 6313 and Sep1, indicating that mutant Sep1 is impaired in the anchoring of this protein to its cell wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/S0378-1097(03)00167-8
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  • 3
    Electronic Resource
    Electronic Resource
    The PEP–pyruvate–oxaloacetate node as the switch point for carbon flux distribution in bacteria (2005)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology reviews 29 (2005), S. 0 
    Details
    ISSN: 1574-6976
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: In many organisms, metabolite interconversion at the phosphoenolpyruvate (PEP)–pyruvate–oxaloacetate node involves a structurally entangled set of reactions that interconnects the major pathways of carbon metabolism and thus, is responsible for the distribution of the carbon flux among catabolism, anabolism and energy supply of the cell. While sugar catabolism proceeds mainly via oxidative or non-oxidative decarboxylation of pyruvate to acetyl-CoA, anaplerosis and the initial steps of gluconeogenesis are accomplished by C3- (PEP- and/or pyruvate-) carboxylation and C4- (oxaloacetate- and/or malate-) decarboxylation, respectively. In contrast to the relatively uniform central metabolic pathways in bacteria, the set of enzymes at the PEP–pyruvate–oxaloacetate node represents a surprising diversity of reactions. Variable combinations are used in different bacteria and the question of the significance of all these reactions for growth and for biotechnological fermentation processes arises. This review summarizes what is known about the enzymes and the metabolic fluxes at the PEP–pyruvate–oxaloacetate node in bacteria, with a particular focus on the C3-carboxylation and C4-decarboxylation reactions in Escherichia coli, Bacillus subtilis and Corynebacterium glutamicum. We discuss the activities of the enzymes, their regulation and their specific contribution to growth under a given condition or to biotechnological metabolite production. The present knowledge unequivocally reveals the PEP–pyruvate–oxaloacetate nodes of bacteria to be a fascinating target of metabolic engineering in order to achieve optimized metabolite production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsre.2004.11.002
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  • 4
    Electronic Resource
    Electronic Resource
    Discrimination of Corynebacterium glutamicum, Brevibacterium flavum and Brevibacterium lactofermentum by restriction pattern analysis of DNA adjacent to the hom gene (1991)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 82 (1991), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract: Different strains of Corynebacterium glutamicum, Brevibacterium flavum, and Brevibacterium lactofermentum were analysed for restriction fragment length polymorphism using the homoserine dehydrogenase gene (hom) as a probe. The hybridization patterns obtained PvuII- or Asp700-restriction of chromosomal DNA were specific and distinguishable for each of the three species and identical for the different strains of each species. Thus, the method employed allows rapid distinction of Corynebacterium glutamicum, Brevibacterium flavum, and Brevibacterium lactofermentum. The former species could also be discriminated from the latter two by its resistance to 0.5 g/l of the methionine analog ethionine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1991.tb04865.x
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  • 5
    Electronic Resource
    Electronic Resource
    Phosphoenolpyruvate carboxylase in Corynebacterium glutamicum is dispensable for growth and lysine production (1993)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 112 (1993), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Phosphoenolpyruvate (PEP) carboxylase is assumed to be of major importance as anaplerotic enzyme in the amino acid producing Corynebacterium glutamicum. We constructed PEP carboxylase-negative strains of the wild-type and of the L-lysine producer MH20–22B by disruption of the respective gene. Analysis of these strains and comparison to the parental strains revealed: (i) identical growth characteristics on all media tested; (ii) identical capacity for lysine production; and (iii) the presence of the alternative anaplerotic enzyme PEP carboxykinase in all four strains. These results show that PEP carboxylase is dispensable as anaplerotic enzyme in C. glutamicum and may indicate that PEP carboxykinase alone can fulfil the anaplerotic function required for growth on glucose and for lysine production.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1993.tb06461.x
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  • 6
    Electronic Resource
    Electronic Resource
    Amplification of three threonine biosynthesis genes inCorynebacterium glutamicum and its influence on carbon flux in different strains (1991)
    Springer
    Applied microbiology and biotechnology 34 (1991), S. 617-622 
    Details
    ISSN: 1432-0614
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Summary The hom-thrB operon (homoserine dehydrogenase/homoserine kinase) and the thrC gene (threonine synthase) of Corynebacterium glutamicum ATCC 13 032 and the hom FBR (homoserine dehydrogenase resistant to feedback inhibition by threonine) alone as well as hom FBR-thrB operon of C. glutamicum DM 368-3 were cloned separately and in combination in the Escherichia coli/C. glutamicum shuttle vector pEK0 and introduced into different corynebacterial strains. All recombinant strains showed 8- to 20-fold higher specific activities of homoserine dehydrogenase, homoserine kinase, and/or threonine synthase compared to the respective host. In wild-type C. glutamicum, amplification of the threonine genes did not result in secretion of threonine. In the lysine producer C. glutamicum DG 52-5 and in the lysine-plus-threonine producer C. glutamicum DM 368-3 overexpression of hom-thrB resulted in a notable shift of carbon flux from lysine to threonine whereas cloning of hom FBR-thrB as well as of hom FBR in C. glutamicum DM 368-3 led to a complete shift towards threonine or towards threonine and its precursor homoserine, respectively. Overexpression of thrC alone or in combination with that of hom FBR and thrB had no effect on threonine or lysine formation in all recombinant strains tested.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00167910
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  • 7
    Electronic Resource
    Electronic Resource
    The phosphoenolpyruvate carboxylase gene of Corynebacterium glutamicum: Molecular cloning, nucleotide sequence, and expression (1989)
    Springer
    Molecular genetics and genomics 218 (1989), S. 330-339 
    Details
    ISSN: 1617-4623
    Keywords: Corynebacterium glutamicum ; Phosphoenolpyruvate carboxylase ; ppc gene
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ppc gene of Corynebacterium glutamicum encoding phosphoenolpyruvate (PEP) carboxylase was isolated by complementation of a ppc mutant of Escherichia coli using a cosmid gene bank of chromosomal c. glutamicum DNA. By subsequent subcloning into the plasmid pUC8 and deletion analysis, the ppc gene could be located on a 3.3 kb SalI fragment. This fragment was able to complement the E. coli ppc mutant and conferred PEP carboxylase activity to the mutant. The complete nucleotide sequence of the ppc gene including 5′ and 3′ flanking regions has been determined and the primary structure of PEP carboxylase was deduced. The sequence predicts a 919 residue protein product (molecular weight of 103154) which shows 34% similarity with the respective E. coli enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00331286
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  • 8
    Electronic Resource
    Electronic Resource
    Molecular aspects of lysine, threonine, and isoleucine biosynthesis inCorynebacterium glutamicum (1993)
    Springer
    Antonie van Leeuwenhoek 64 (1993), S. 145-163 
    Details
    ISSN: 1572-9699
    Keywords: isolecucine biosynthesis ; lysine ; threonine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The Gram-positive bacteriumCorynebactericum glutamicum is used for the industrial production of amino acids, e.g. of L-glutamate and L-lysine. In the last ten years genetic engineering methods were developed forC. glutamicum and consequently, recombinant DNA technology was employed to study the biosynthetic pathways and to improve the amino acid productivity by manipulation of enzymatic, transport and regulatory functions of this bacterium. The present review summarizes the current knowledge on the synthesis and over-production of the aspartate derived amino acids L-lysine, L-threonine and L-isoleucine inC. glutamicum. A special feature ofC. glutamicum is its abilily to convert the lysine intermediate piperideine2,6-dicarboxylate to diaminopimelate by two different routes, i.e. by reactions involving succinylated intermediates or by the single reaction of diaminopimelate dehydrogenase. The flux distribution over the two pathways is regulated by the ammonium availability. The overall carbon flux from aspartate to lysine, however, is governed by feedback-control of the aspartate kinase and by the level of dihydrodipicolinate synthase. Consequently, expression oflysC FBR encoding a deregulated aspartate kinase and/or the overexpression ofdapA encoding dihydrodipicolinate synthase led to overproduction of lysine. As a further specific featureC. glutamicum possesses a specific lysine export carrier which shows high activity in lysine overproducing mutants. Threonine biosynthesis is in addition to control by the aspartate kinase tightly regulated at the level of homoserine dehydrogenase which is subject to feedback-inhibition and to repression.C. glutamicum strains possessing a deregulated aspartate kinase and a deregulated homoserine dehydrogenase produce lysine and threonine. Amplification of deregulated homoserine dehydrogenase in such strain led to an almost complete redirection of the carbon flux to threonine. For a further flux from threonine to isoleucine the allosteric control of threonine dehydratase and of the acetohydroxy acid synthase are important. The expression of the genes encoding the latter enzyme is additionally regulated at the transcriptional level. By addition of 2-oxobutyrate as precursor and by bypassing the expression control of the acetohydroxy acid synthase genes high isoleucine overproduction can be obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00873024
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  • 9
    Electronic Resource
    Electronic Resource
    Ammonia assimilation in Corynebacterium glutamicum and a glutamate dehydrogenase-deficient mutant (1998)
    Springer
    Biotechnology letters 20 (1998), S. 953-957 
    Details
    ISSN: 1573-6776
    Keywords: Corynebacterium glutamicum ; ammonia assimilation ; glutamate dehydrogenase ; glutamine synthetase ; glutamate synthase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract In the wild-type of Corynebacterium glutamicum, the specific activity of glutamate dehydrogenase (GDH) remained constant at 1.3 U (mg protein)−1 when raising the ammonia (NH4) concentration in the growth medium from 1 to 90 mM. In contrast, the glutamine synthetase (GS) and glutamate synthase (GOGAT) activities decreased from 1.1 U (mg protein)−1 and 42 mU (mg protein)−1, respectively, to less than 10 % of these values at NH4 concentrations 〉 10 mM suggesting that under these conditions the GDH reaction is the primary NH4 assimilation pathway. Consistent with this suggestion, a GDH-deficient C. glutamicum mutant showed slower growth at NH4 concentrations ≥ 10 mM and, in contrast to the wild-type, did not grow in the presence of the GS inhibitor methionine sulfoximine. © Rapid Science Ltd. 1998
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005406126920
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