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  • 1
    Electronic Resource
    Electronic Resource
    Cloning and characterization of the Neisseria gonorrhoeae MS11 folC gene (1996)
    Springer
    Molecular genetics and genomics 250 (1996), S. 277-285 
    Details
    ISSN: 1617-4623
    Keywords: Key words Gonococcus ; Folic acid ; Dihydrofolate synthetase ; Folylpolyglutamate synthetase ; One-carbon metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: 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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02174385
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  • 2
    Electronic Resource
    Electronic Resource
    Construction of hermes shuttle vectors: a versatile system useful for genetic complementation of transformable and non-transformableNeisseria mutants (1996)
    Springer
    Molecular genetics and genomics 250 (1996), S. 558-569 
    Details
    ISSN: 1617-4623
    Keywords: Plasmid vector ; Conjugation ; Generalized mutagenesis ; Homologous recombination ; Natural transformation competence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A versatile shuttle system has been developed for genetic complementation with cloned genes of transformable and non-transformableNeisseria mutants. By random insertion of a selectable marker into the conjugativeNeisseria plasmidptetM25.2, a site within this plasmid was identified that is compatible with plasmid replication and with conjugative transfer of plasmid. Regions flanking the permissive insertion site of ptetM25.2 were cloned inEscherichia coli and served as a basis for the construction of the Hermes vectors. Hermes vectors are composed of anE. coli replicon that does not support autonomous replication inNeisseria, e.g. ColE1, p15A, orori fd, fused with a shuttle consisting of a selectable marker and a multiple cloning site flanked by the integration region of ptetM25.2. Complementation of a non-transformableNeisseria strain involves a three-step process: (i) insertion of the desired gene into a Hermes vector; (ii) transformation of Hermes into aNeisseria strain containing ptetM25.2 to create a hybrid ptetM25.2 via gene replacement by the Hermes shuttle cassette; and (iii) conjugative transfer of the hybrid ptetM25.2 into the finalNeisseria recipient. Several applications for the genetic manipulation of pathogenicNeisseriae are described.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02174444
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  • 3
    Electronic Resource
    Electronic Resource
    Nucleotide sequence of ompV, the gene for a major Vibrio cholerae outer membrane protein (1986)
    Springer
    Molecular genetics and genomics 205 (1986), S. 494-500 
    Details
    ISSN: 1617-4623
    Keywords: Signal sequence ; Gene regulation ; Export ; Codon usage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The nucleotide sequence of the ompV gene of Vibrio cholerae was determined. The product of the gene is a 28,000 dalton protein which, after the removal of a 19 amino acid signal sequence, produces a mature outer membrane protein of 26,000 daltons. The cleavage site was determined by amino-terminal amino acid sequencing of the purified mature protein. The DNA upstream of the gene shows the presence of a typical promoter region as judged from the Escherichia coli consensus information; however, the Shine-Dalgarno sequence is associated with a region capable of forming a secondary structure in the mRNA. The formation of this structure would inhibit binding of the mRNA to the ribosome and reduce translation. It is proposed that this structure is recognized by a positive activator in V. cholerae and because of its absence in E. coli ompV is poorly expressed. The distribution of rare codons within ompV suggests that they may serve to slow down the translation of particular domains such that the nascent polypeptide has an opportunity to take up its conformation without interference from the later formed regions. Such a mechanism could aid localization of the protein if export were by a cotranslational secretion system.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338088
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  • 4
    Electronic Resource
    Electronic Resource
    Recognition of two initiation codons for the synthesis of phage fd gene 2 protein (1980)
    Springer
    Molecular genetics and genomics 180 (1980), S. 489-494 
    Details
    ISSN: 1617-4623
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Bacteriophage fd gene 2 protein was specifically labeled with radioactive amino acids and was isolated from membranous cell structures as an apparently homogenous protein. Amino acid sequence analysis revealed that the protein was initiated at two distinct AUG codons close to the ribosome binding site. The two resulting translation products were found to begin with a deformylated methionine residue. Initiation at the first signal was used for 90% of the chains and at the second signal for 10% of the sequenced molecules. The use of one or the other chain start may influence functions of gene 2 protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00268051
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  • 5
    Electronic Resource
    Electronic Resource
    Serological properties and processing in Escherichia coli K12 of OmpV fusion proteins of Vibrio cholerae (1986)
    Springer
    Molecular genetics and genomics 205 (1986), S. 501-506 
    Details
    ISSN: 1617-4623
    Keywords: Signal sequence ; Antigenic epitopes ; Outer membrane protein ; Immunogenicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Fusion proteins comprising the amino-terminal 99 amino acids of the bacteriophage MS2 replicase and various portions of OmpV a major outer membrane protein of Vibrio cholerae were expressed in Escherichia coli K12. These fusions were expressed under the control of the PL promoter of bacteriophage λ, and expression was controlled using a cIts repressor. Fusions occurring within the secretory signal sequence of OmpV gave rise to the production of mature OmpV. The efficiency, however, decreased with progressive deletion of the signal sequence within the fusions. The reactivity of various OmpV fusions with antisera raised against purified OmpV and whole bacteria demonstrated the existence of two antigenic domains: one present in the denatured form and another in the membrane-associated form of OmpV. These domains correspond to markedly hydrophilic regions of the protein as would be predicted for surface-exposed epitopes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00338089
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  • 6
    Electronic Resource
    Electronic Resource
    Isolation and culturing of highly polarized primary epithelial cells from normal human stomach (antrum) as spheroid-like vesicles (1997)
    Springer
    Methods in cell science 19 (1997), S. 169-178 
    Details
    ISSN: 1573-0603
    Keywords: Antrum ; Human gastrointestinal epithelium ; Polarized epithelial cells ; Spheroid-like vesicles ; Tissue culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A novel procedure is described for the three-dimensional (3-D) in vitro culture and for maintaining of nontransformed gastric epithelial cells from the human antrum mucosa (HAEC). Biopsies obtained from the antrum were cut into small pieces and the tissue fragments were incubated in culture medium containing the appropriate antibiotics. The suspended mucosal fragments generated small, spheroid-like vesicles consisting of predominantly highly prismatic, mucus-producing cells which mimic the in vivo counterparts structurally and functionally. Electron microscopic investigations revealed a number of ultrastructural and morphological features similar to those of normal gastric cells in vivo such as apical microvilli associated with a glycocalyx, tight junctions, desmosomes, membraneous infoldings, mucous droplets, and an irregular basal lamina. In comparison to the two-dimensional (2-D) gastric cell cultures grown on plane supports, the vesicles maintain an intact epithelial organization of individual cells. The prismatic phenotype, the histophysiology as well as the cytoarchitecture of the non-transformed 3-D cultured gastric epithelial cells are comparable to those of the native tissue and therefore represent a suitable model for defined pathogen-host cell interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1009751913391
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular principles of antigenic variation in Neisseria gonorrhoeae (1987)
    Springer
    Antonie van Leeuwenhoek 53 (1987), S. 431-434 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome of Neisseria gonorrhoeae harbours many gene loci for the production of variant pili. Strain MS11 has two expression genes (pilE) with promoter and complete coding sequences. The remaining genes are silent (pilS) lacking the promoter and the conservative amino terminals coding sequences of pilin. The pilus genes consist of six variable minicassettes (mc's), that are flancked by strictly conserved sequences. Upon phase (P+ to P+) and antigenic (P+ to P−, or vice versa) transitions minicassettes from silent loci are transferred from silent pilus gene copies to the expression gene by gene conversion. P− variants resulting from such rearrangements still produce pilin mRNA as well as pilin, but only a few are found on the surface of those gonococci.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00415498
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  • 8
    Electronic Resource
    Electronic Resource
    Virulence functions and antigen variation in pathogenic Neisseriae (1988)
    Springer
    Antonie van Leeuwenhoek 54 (1988), S. 421-430 
    Details
    ISSN: 1572-9699
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00461860
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