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  • 1
    Electronic Resource
    Electronic Resource
    Cytochrome c maturation proteins are critical for in vivo growth of Legionella pneumophila (2004)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 241 (2004), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Legionella pneumophila, an intracellular parasite of macrophages and protozoa, requires iron for extra- and intracellular growth. In a new screen of a mutant library of L. pneumophila for strains defective for growth on agar media lacking supplemental iron, seven mutants were obtained. All of the mutants had a disruption in the cytochrome c maturation (ccm) locus; two had insertions in ccmB, two in ccmC, and three in ccmF. The ccm mutants were unable to multiply within macrophage-like cells (i.e., U937 and THP-1 cells) and Hartmannella vermiformis amoebae. A competition assay in A/J mice revealed that ccm mutants are severely defective for growth within the lung. Taken together, these data confirm that ccm and cytochrome c maturation proteins are required for L. pneumophila growth in low iron, intracellular infection, and virulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/j.femsle.2004.10.028
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  • 2
    Electronic Resource
    Electronic Resource
    The prepilin peptidase is required for protein secretion by and the virulence of the intracellular pathogen Legionella pneumophila (1999)
    Oxford BSL : Blackwell Science Ltd
    Molecular microbiology 31 (1999), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Prepilin peptidases cleave, among other substrates, the leader sequences from prepilin-like proteins that are required for type II protein secretion in Gram-negative bacteria. To begin to assess the importance of type II secretion for the virulence of an intracellular pathogen, we examined the effect of inactivating the prepilin peptidase (pilD ) gene of Legionella pneumophila. Although the pilD mutant and its parent grew similarly in bacteriological media, they did differ in colony attributes and recoverability from late stationary phase. Moreover, at least three proteins were absent from the mutant's supernatant, indicating that PilD is necessary for the secretion of Legionella proteins. The absence of both the major secreted protein and a haemolytic activity from the mutant signalled that the L. pneumophila zinc metalloprotease is excreted via type II secretion. Most interestingly, the pilD mutant was greatly impaired in its ability to grow within Hartmannella vermiformis amoebae and the human macrophage-like U937 cells. As reintroduction of pilD into the mutant restored infectivity and as a mutant lacking type IV pilin replicated like wild type, these data suggested that the intracellular growth of L. pneumophila is promoted by proteins secreted via a type II pathway. Intratracheal inoculation of guinea pigs revealed that the LD50 for the pilD mutant is at least 100-fold greater than that for its parent, and the culturing of bacteria from infected animals showed a rapid clearance of the mutant from the lungs. This is the first study to indicate a role for PilD and type II secretion in intracellular parasitism.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2958.1999.01239.x
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  • 3
    Electronic Resource
    Electronic Resource
    MicroReview: Impact of the bacterial type I cytochrome c maturation system on different biological processes (2005)
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 56 (2005), S. 0 
    Details
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: In the α-, β- and γ-Proteobacteria, the so-called cytochrome c maturation (Ccm) system is known to promote the covalent attachment of the haem to periplasmic apocytochrome c. However, in species of Pseudomonas, Rhizobium, Paracoccus and Legionella, mutations in ccm genes result in phenotypes that cannot be readily explained by the simple loss of a c-type cytochrome. These phenotypes include loss of siderophore production and utilization, reduced abilities to grow in low-iron conditions and in mammalian and protozoan host cells, and alterations in copper sensitivity and manganese oxidation. These various data suggest that Ccm proteins may perform one or more functions in addition to Ccm, which are critical for bacterial physiology and growth. Novel hypotheses that should be explored include the utilization of Ccm-associated haem for processes besides attachment to apocytochrome c, the export of a non-haem compound through the Ccm system, and the negative effects of protoporphyrin IX accumulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2958.2005.04650.x
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  • 4
    Electronic Resource
    Electronic Resource
    Extended host range of a β-related corynebacteriophage (1996)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 140 (1996), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Unlike most β-related phages isolated from Corynebacterium diphtheriae, phage 782 readily plaqued on strains of C. ulcerans and C. pseudotuberculosis. The extended host range of phage 782 was not, however, due to a greater ability of the phage to adsorb to bacterial surfaces. Using chemical mutagenesis, a number of phage mutants were isolated which had diminished capacities to infect C. ulcerans, suggesting the existence of a locus (ehr) for extended host range. Pre-lysogenization of C. ulcerans strains with phage 782, but not its mutant form or other β-related phages, rendered them susceptible to infection by previously excluded phages. An examination of recombinants between phages 782, 17, and β localized ehr to a 7 kilobase region of DNA including attP. The data are compatible with the notion that ehr encodes an anti-restriction function.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1996.tb08340.x
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  • 5
    Electronic Resource
    Electronic Resource
    Random mutagenesis of Legionella pneumophila with mini-Tn10 (1994)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 124 (1994), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract To more effectively study the genetic basis of Legionnaires' disease, we characterized a system for mini-Tn10 mutagenesis in Legionella pneumophila. The mini-transposons were first electroporated into Legionella on counterselectable vectors expressing altered target site transposases. Then, by simultaneously selecting for the kanamycin-resistance gene within the transposon and counterselecting against the maintenance of the plasmid, we directly and readily isolated strains bearing single chromosomal insertions. Southern hybridization analysis further demonstrated that the insertions were randomly distributed throughout the Legionella genome. The mini-Tn10 insertions were stable during extracellular and intracellular growth, and did not alter the infectivity of L. pneumophila. Thus, this mutagenesis system offers an easy, one-step approach toward isolating large populations of random mutants which can be screened for defects in virulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1994.tb07269.x
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  • 6
    Electronic Resource
    Electronic Resource
    DNA sequence homology between attB-related sites of Corynebacterium diphtheriae, Corynebacterium ulcerans, Corynebacterium glutamicum, and the attP side of γ-Cornephage (1990)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 66 (1990), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Chromosomal restriction fragments of Corynebacterium ulcerans and C. diphtheriae, containing an integration site for corynephages of the β family, show homology on Southern blots. Homologous DNA in also found in the soil isolate C. glutamicum, although this strain is not susceptible to gb-corynephages. Three of these DNA fragments, one for each bacterial strain, and a fragment of γ-corynephage DNA previously shown to contain the phage integration site, were cloned and sequenced. Alignment of the 3 bacterial sequences shows a very high degreee of homology in a stretch of ca 120 nucleotides, whereas the rest of the sequences is generally non-homologous. Within this common bacterial portion, a segment of ca. 96 nucleotides (core sequence) is also highly homologous to the plague sequence. The first half (ca. 50 bp) of the core sequence is identical in all aligned sequences whereas the second half, which is largely occupied by a stem-and-loop structure, contains point mutations peculiar to each clone. The described sequences are likely to be involved in phage integration/excision processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1990.tb04015.x
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  • 7
    Electronic Resource
    Electronic Resource
    Site-specific mutagenesis in Legionella pneumophila by allelic exchange using counterselectable ColE1 vectors (1988)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 56 (1988), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract To study the molecular pathogenesis of infection by Legionella pneumophila, a technique of site-specific mutagenesis by allelic exchange was evaluated. To develop this system, we optimized conjugal DNA transfer by isolating a mutant that functions 1000-fold more efficiently as a recipient than the wild type strain, identified two counter-selectable markers, rpsL and sacB, that function in L. pneumophila, and constructed a counterselectable Co1E1 vector. Allelic exchange of a L. pneumophila chrosomal gene was achieved at a frequency of 10−5 per transconjugant. The allelic exchange procedure itself did not alter the ability of L. pneumophila to infect macrophages, indicating that the system can be used to study this aspect of virulence.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1988.tb03178.x
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  • 8
    Electronic Resource
    Electronic Resource
    Detection of mip-like sequences and mip-related proteins within the family Rickettsiaceae (1995)
    Springer
    Current microbiology 30 (1995), S. 149-153 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The Mip surface protein, a prokaryotic analog of the FK506-binding proteins, enhances the ability of Legionella pneumophila to infect macrophages and protozoa. Using mip-specific probes and low-stringency Southern hybridizations, we have detected DNA sequences homologous to mip within Coxiella burnetii and Rochalimaea quintana. Using specific anti-Mip antisera and immunoblot analysis, we also detected Mip-related proteins within these bacteria as well as within Rickettsia and Ehrlichia species. These data suggest that Mip-related proteins have broad significance for host-parasite interactions. However, they also indicate that care must be exercised when using mip probes or anti-Mip antibodies for the detection of Legionella organisms in water or clinical samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00296200
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  • 9
    Electronic Resource
    Electronic Resource
    Infectivity of Legionella pneumophila mip mutant for alveolar epithelial cells (1995)
    Springer
    Current microbiology 30 (1995), S. 247-250 
    Details
    ISSN: 1432-0991
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Legionella pneumophila can invade and grow within explanted alveolar epithelial cells. Given its potential clinical significance, an examination of the molecular basis of epithelial cell infection was initiated. The mip gene encodes a 24-kilodalton surface protein that promotes macrophage infection and virulence. To determine whether this gene is required for pneumocyte infection, we tested a strain bearing a mip null mutation for its ability to infect both explanted type II cells and type I-like cell lines. For infection of type II cells, the infective dose 50% for the Mip- strain was 25-fold higher than an isogenic Mip+ strain. Type I cell monolayers infected with the mutant for 3 days yielded ∼ 50-fold fewer bacteria than did monolayers infected with the parental strain. These data indicate that Mip enhances infection of pneumocytes and that L. pneumophila employs some of the same genes (mechanisms) to infect epithelial cells and marcophages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00293641
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  • 10
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    Type II secretion: a protein secretion system for all seasons (2005)
    Cell Press
    Details
    Publication Date: 2005-12-01
    Print ISSN: 0966-842X
    Electronic ISSN: 1878-4380
    Topics: Biology
    Published by Cell Press
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