Abstract:
:Legionella pneumophila expresses two catalase-peroxidase enzymes that exhibit strong peroxidatic but weak catalatic activities, suggesting that other enzymes participate in decomposition of hydrogen peroxide (H2O2). Comparative genomics revealed that L. pneumophila and its close relative Coxiella burnetii each contain two peroxide-scavenging alkyl hydroperoxide reductase (AhpC) systems: AhpC1, which is similar to the Helicobacter pylori AhpC system, and AhpC2 AhpD (AhpC2D), which is similar to the AhpC AhpD system of Mycobacterium tuberculosis. To establish a catalatic function for these two systems, we expressed L. pneumophila ahpC1 or ahpC2 in a catalase/peroxidase mutant of Escherichia coli and demonstrated restoration of H2O2 resistance by a disk diffusion assay. ahpC1::Km and ahpC2D::Km chromosomal deletion mutants were two- to eightfold more sensitive to H2O2, tert-butyl hydroperoxide, cumene hydroperoxide, and paraquat than the wild-type L. pneumophila, a phenotype that could be restored by trans-complementation. Reciprocal strategies to construct double mutants were unsuccessful. Mutant strains were not enfeebled for growth in vitro or in a U937 cell infection model. Green fluorescence protein reporter assays revealed expression to be dependent on the stage of growth, with ahpC1 appearing after the exponential phase and ahpC2 appearing during early exponential phase. Quantitative real-time PCR showed that ahpC1 mRNA levels were approximately 7- to 10-fold higher than ahpC2D mRNA levels. However, expression of ahpC2D was significantly increased in the ahpC1 mutant, whereas ahpC1 expression was unchanged in the ahpC2D mutant. These results indicate that AhpC1 or AhpC2D (or both) provide an essential hydrogen peroxide-scavenging function to L. pneumophila and that the compensatory activity of the ahpC2D system is most likely induced in response to oxidative stress.
journal_name
J Bacterioljournal_title
Journal of bacteriologyauthors
LeBlanc JJ,Davidson RJ,Hoffman PSdoi
10.1128/JB.00635-06subject
Has Abstractpub_date
2006-09-01 00:00:00pages
6235-44issue
17eissn
0021-9193issn
1098-5530pii
188/17/6235journal_volume
188pub_type
杂志文章abstract::Sequences of the major outer membrane protein (MOMP) gene (ompA) and the outer membrane complex B protein gene (omcB) from Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci were analyzed for evidence of intragenic recombination and for linkage equilibrium. The Sawyer runs test, compatibility matrices...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.183.20.5997-6008.2001
更新日期:2001-10-01 00:00:00
abstract::The formation of bacteriolytic enzymes of Staphylococcus aureus, with special reference to strain M18, was investigated under a variety of conditions. The bacteriolytic activity was tested by using whole cells of Micrococcus lysodeikticus as a substrate. Complex media were required for production, and a Casein Hydroly...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.104.1.227-233.1970
更新日期:1970-10-01 00:00:00
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journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.175.15.4605-4614.1993
更新日期:1993-08-01 00:00:00
abstract::The double-stranded DNA bacteriophage PRD1 uses an IncP plasmid-encoded conjugal transfer complex as a receptor. Plasmid functions in the PRD1 life cycle are restricted to phage adsorption and DNA entry. A single phage structural protein, P2, located at the fivefold capsid vertices, is responsible for PRD1 attachment ...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.181.21.6689-6696.1999
更新日期:1999-11-01 00:00:00
abstract::An increased demand for cytochromes is associated with symbiotic development and microaerobic metabolism in the bacterium Bradyrhizobium japonicum, and evidence suggests that hemB, rather than hemA, is the first essential bacterial heme synthesis gene in symbiosis with soybean. Steady-state levels of mRNA and protein ...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.179.11.3706-3710.1997
更新日期:1997-06-01 00:00:00
abstract::The Escherichia coli strain cs2-68 is a cold-sensitive (c) mutant that forms a long filamentous cell at 20 degrees C with a large nucleoid mass in its central region. We have recently shown that the pcsA68 mutation causing the cs phenotype is a single-base substitution within the dinD gene, a DNA damage-inducible gene...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.178.13.3854-3859.1996
更新日期:1996-07-01 00:00:00
abstract::A mutation in Escherichia coli leads to the loss of ribosomal protein L24, severely impaired growth, and a temperature-sensitive phenotype. The mutation was shown to be in rplX, the gene for protein L24, and was due to the alteration of an AAA codon to a TAA stop codon at position 61 in rplX that resulted in a 20-amin...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.163.3.890-894.1985
更新日期:1985-09-01 00:00:00
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journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.173.17.5414-5418.1991
更新日期:1991-09-01 00:00:00
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journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.178.4.1141-1145.1996
更新日期:1996-02-01 00:00:00
abstract::The glucosamine-1-phosphate acetyltransferase activity but not the uridyltransferase activity of the bifunctional GlmU enzyme from Escherichia coli was lost when GlmU was stored in the absence of beta-mercaptoethanol or incubated with thiol-specific reagents. The enzyme was protected from inactivation in the presence ...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.180.18.4799-4803.1998
更新日期:1998-09-01 00:00:00
abstract::Selenium is a constituent in Escherichia coli of the anaerobic enzyme formate dehydrogenase in the form of selenocysteine. Selenium is also present in the tRNA of E. coli in the modified base 5-methylaminomethyl-2-selenouracil (mnm5Se2U). The pathways of bacterial selenium metabolism are largely uncharacterized, and i...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.170.2.736-743.1988
更新日期:1988-02-01 00:00:00
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journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.123.1.36-40.1975
更新日期:1975-07-01 00:00:00
abstract::The effects of high doses of radiation (1, 5, or 20 Mrad) on the toxicity, pyrogenicity, and immunogenicity of Salmonella typhimurium cells and endotoxin were studied. Toxicity decreased progressively after exposure to 1, 5, or 20 Mrad. The lethal effect of 1-Mrad exposed cells was greater than that of heat-, acetone-...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.95.6.2165-2170.1968
更新日期:1968-06-01 00:00:00
abstract::Mutations in two chromosomal genes of Escherichia coli, cpxA and cpxB, produced a temperature-sensitive growth defect that was remedied specifically by the addition of isoleucine and valine to the minimal medium. This auxotrophy was manifested only when the medium contained exogenous leucine, suggesting that mutant ce...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.144.1.68-73.1980
更新日期:1980-10-01 00:00:00
abstract::Expression of a circadian rhythm of conidiation in Neurospora crassa is enhanced in cultures grown on medium that is neutral or deficient in biotin. ...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.123.1.387-389.1975
更新日期:1975-07-01 00:00:00
abstract::The sugar composition of lipopolysaccharide (LPS) isolated from whole cells of Alteromonas haloplanktis 214 (previously referred to as marine pseudomonas B-16, ATCC 19855), variant 3, of the lipid A, core, and side-chain fractions derived from it, and of the LPS fractions (LPS I, II, and III) obtained by subjecting it...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.136.1.158-167.1978
更新日期:1978-10-01 00:00:00
abstract::Degradation of 2-hydroxy-5-carboxymethylmuconic semialdehyde, the ring fission product of the 4-hydroxyphenylacetate meta-cleavage pathway, by mutant strains P23X19 and P23X16 of Pseudomonas putida NCI B 9865 was studied. Both mutants were unable to grow on either 4-hydroxyphenylacetate of 3,4-dihydroxyphenylacetate. ...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.142.2.480-485.1980
更新日期:1980-05-01 00:00:00
abstract::The origin of replication of the plasmid R1162 contains an initiation site for the synthesis of each DNA strand. When one of these sites (oriL) is deleted, synthesis on the corresponding strand is no longer initiated efficiently in vitro by the R1162-encoded replication proteins, and the plasmid is no longer stably ma...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.178.16.4870-4876.1996
更新日期:1996-08-01 00:00:00
abstract::The ugp operon of Escherichia coli includes genes involved in the uptake of sn-glycerol-3-phosphate and glycerophosphoryl diesters and belongs to the pho regulon which is induced by phosphate limitation. This operon has two transcriptional initiation sites, as determined by S1 nuclease mapping of the in vivo transcrip...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.173.2.549-558.1991
更新日期:1991-01-01 00:00:00
abstract::Campylobacter jejuni remains among the leading causes of bacterial food-borne illness. The current understanding of Campylobacter physiology suggests that it is asaccharolytic and is unable to catabolize exogenous carbohydrates. Contrary to this paradigm, we provide evidence for l-fucose utilization by C. jejuni. The ...
journal_title:Journal of bacteriology
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更新日期:2011-03-01 00:00:00
abstract::We have used a plasmid-based transcriptional reporter system to examine the transcriptional effects of 33 single point mutations in the box A region (TATA-like sequence) of the Haloferax volcanii tRNA(Lys) promoter. The most pronounced effects on transcriptional efficiency were found when the nucleotides corresponding...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.177.7.1844-1849.1995
更新日期:1995-04-01 00:00:00
abstract::Streptococcus salivarius, a gram-positive bacterium found in the human oral cavity, expresses flexible peritrichous fimbriae. In this paper, we report purification and partial characterization of S. salivarius fimbriae. Fimbriae were extracted by shearing the cell surface of hyperfimbriated mutant A37 (a spontaneous m...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.183.9.2724-2732.2001
更新日期:2001-05-01 00:00:00
abstract::Streptococcus agalactiae (group B streptococcus [GBS]) is a major cause of infections in newborns, pregnant women, and immunocompromised patients. GBS strain CNCTC10/84 is a clinical isolate that has high virulence in animal models of infection and has been used extensively to study GBS pathogenesis. Two unusual featu...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.00504-20
更新日期:2020-11-04 00:00:00
abstract::The lethal and mutagenic effects of various mutagens on Neisseria gonorrhoeae were investigated. Lethality studies demonstrated that N. gonorrhoeae was relatively sensitive to ethyl methanesulfonate, UV light, and methyl methanesulfonate. Although N. gonorrhoeae was readily mutated by ethyl methanesulfonate and N-meth...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.160.1.288-293.1984
更新日期:1984-10-01 00:00:00
abstract::Two distinct phenotypic classes of lysine requiring auxotrophs of Escherichia coli are described. Mutants of the LysA class produce little or no active diaminopimelic acid (DAP) decarboxylase and specifically require lysine for growth. Mutants of the LysB class produce a cryptic DAP decarboxylase which can be activate...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.105.3.988-998.1971
更新日期:1971-03-01 00:00:00
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journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.179.20.6408-6415.1997
更新日期:1997-10-01 00:00:00
abstract::The genetic organization of the polypeptides required for the biosynthesis of the F41 adhesin of enterotoxigenic Escherichia coli strains was investigated. Maxicell analysis demonstrated that a recombinant plasmid which mediated mannose-resistant hemagglutination and F41 antigen production encoded four polypeptides of...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.170.10.4890-4896.1988
更新日期:1988-10-01 00:00:00
abstract::A 6.2-kb region of DNA corresponding to complementation groups II and III of the Erwinia amylovora hrp gene cluster was analyzed. Transposon mutagenesis indicated that the two complementation groups are required for secretion of harpin, an elicitor of the hypersensitive reaction. The sequence of the region revealed 10...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/jb.179.5.1690-1697.1997
更新日期:1997-03-01 00:00:00
abstract::Using a quantitative assay for measuring chemotaxis, we tested a variety of sugars and sugar derivatives for their ability to attract Escherichia coli bacteria. The most effective attractants, i.e., those that have thresholds near 10(-5) M or below, are N-acetyl-d-glucosamine, 6-deoxy-d-glucose, d-fructose, d-fucose, ...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.115.3.824-847.1973
更新日期:1973-09-01 00:00:00
abstract::The spx gene encodes an RNA polymerase-binding protein that exerts negative and positive transcriptional control in response to oxidative stress in Bacillus subtilis. It resides in the yjbC-spx operon and is transcribed from at least five promoters located in the yjbC regulatory region or in the yjbC-spx intergenic re...
journal_title:Journal of bacteriology
pub_type: 杂志文章
doi:10.1128/JB.01520-06
更新日期:2007-03-01 00:00:00