共查询到20条相似文献,搜索用时 15 毫秒
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D. Raffelsbauer A. Bubert F. Engelbrecht J. Scheinpflug A. Simm J. Hess S. H. E. Kaufmann W. Goebel 《Molecular genetics and genomics : MGG》1998,260(2-3):144-158
In this work we identified and characterized a gene cluster containing three internalin genes of Listeria monocytogenes EGD. These genes, termed inlG, inlH and inlE, encode proteins of 490, 548 and 499 amino acids, respectively, which belong to the family of large, cell wall-bound internalins. The inlGHE gene cluster is flanked by two listerial house-keeping genes encoding proteins homologous to the 6-phospho-β-glucosidase and the succinyl-diaminopimelate desuccinylase of E. coli. A similar internalin gene cluster, inlC2DE, localised to the same position on the L. monocytogenes EGD chromosome was recently described in a different isolate (Dramsi S, Dehoux P, Lebrun M, Goossens PL, Cossart P (1997) Infect Immun 65: 1615–1625). Sequence comparison of the two inl gene clusters indicates that inlG is a new internalin gene, while inlH was generated by a site-specific recombination, leading to an in-frame deletion which removed the 3′-terminal end of inlC2 and the 5′-terminal part of inlD. The third gene of the inlGHE cluster, inlE, is almost identical to the previously reported inlE gene. Our data show that the inlGHE gene cluster is probably transcribed from a major PrfA- independent promoter located upstream of inlG. PCR analysis revealed the presence of the newly identified inl genes inlG and inlH in most L. monocytogenes isolates tested. A mutant which has lost inlG, inlH and inlE by an in-frame deletion exhibited, after oral infection of mice, a significant loss in virulence and shows drastically reduced numbers of viable bacteria in both liver and spleen when compared to the wild-type strain. 相似文献
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A single cell of Listeria monocytogenes attached on food contact surfaces can be a potential source of cross-contamination in a food-processing plant. To see whether
internalin A (InlA) and B (InlB), major surface proteins on L. monocytogenes, play a significant role in the attachment process, wild-type L. monocytogenes EGD (LM_EGD) and its isogenic internalin-negative mutants (LM_EGDΔinlA, LM_EGDΔinlB, and LM_EGDΔinlAB) were used to determine attachment strength on inert glass surface. Western blot analysis using InlA and InlB antibodies
confirmed the absence of InlA in LM_EGDΔinlA, InlB in LM_EGDΔinlB, and both InlA and InlB in LM_EGDΔinlAB. Regardless of initial attachment numbers, LM_EGD which expressed both InlA and InlB proteins exhibited the strongest attachment
strength while the double mutant (LM_EGDΔinlAB) exhibited the weakest. The two single mutants (LM_EGDΔinlA and LM_EGDΔinlB) that expressed only one type of the internalins were shown to have intermediate attachment strength. These results suggest
that both InlA and InlB expression play a significant role in the attachment strength of L. monocytogenes on glass surface. 相似文献
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A new PrfA-regulated gene of Listeria monocytogenes encoding a small, secreted protein which belongs to the family of internalins 总被引:8,自引:5,他引:3
Fredi Engelbrecht Soo-Kyung Chun Christian Ochs Jürgen Hess Friedrich Lottspeich Werner Goebel & Zeljka Sokolovic 《Molecular microbiology》1996,21(4):823-837
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G. Papatzimos C. Kotzamanidis M. Kyritsi E. Malissiova V. Economou V. Giantzi A. Zdragas C. Hadjichristodoulou D. Sergelidis 《Letters in applied microbiology》2022,74(3):367-376
In this study, we investigated the incidence of Listeria monocytogenes in the receiving meat, the meat products, the personnel and the environment of a vertically integrated company in Northern Greece owing a processing plant and three trading facilities. A total of 303 samples were examined from the receiving raw meat, raw meat preparations, ready-to-eat meat products, processing surfaces and the environment of these facilities as well as the food handlers’ hands and nasal cavities. MALDI-TOF MS was used for Listeria identification; from the 22 (7·26%) positive to Listeria spp. isolates, 12 (3·96%) identified as L. monocytogenes, eight (2·64%) as Listeria innocua and two (0·66%) as Listeria welshimeri. Molecular serotyping of L. monocytogenes isolates by multiplex PCR revealed 11 strains belonging to serogroup IIa (1/2a and 3a) and one to IIc (1/2c and 3c). The assay for the detection of the virulence-associated genes revealed eight isolates carrying all the examined genes (inlA, inlB, inlC, plcA, prfA, actA, hlyA and iap) and four carrying all except the actA gene. Eleven (91·7%) of the isolates showed a strong ability to form biofilm. All isolates were multidrug resistant. The MALDI-TOF Main Spectrum Profile (MSPs), revealed three clusters: one with five isolates (four from environmental samples and one from a food handler), one with five isolates (all from environmental samples) and one with two isolates (both from raw meat products). MALDI-TOF MS seems to be a reliable tool for the identification of niches and contamination routes in processing plants, contributing also to the evaluation and improvement of the applied preventive measures to control L. monocytogenes. 相似文献
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REC114 is one of 10 genes known to be required for the initiation of meiotic recombination in Saccharomyces cerevisiae. It is transcribed only in meiosis, and our previous sequence analysis suggested the presence of an intron in the 3′ end
of the gene. Hypotheses in the literature have suggested, because of its unusual location, either that the putative intron
in REC114 is likely to be necessary for expression, or that there may actually be no intron present. This work demonstrates that REC114 does have an intron and is one of only three genes in yeast with introns located in the 3′ end. Furthermore, the 3′ splice
site utilized in REC114 is a very rare AAG sequence; only three other genes in yeast use this nonconsensus sequence. The splicing of REC114 does not require MER1, a gene known to be involved in meiosis-specific RNA processing. In fact, an intronless copy of REC114 can complement a null rec114 mutation. Thus, it does not appear that the intron is essential for expression of REC114. Although the intron is not absolutely required for meiotic function, it is conserved in evolution; two other species of
yeast contain an intron at the same location in their REC114 genes.
Received: 16 October 1996 / Accepted: 10 February 1997 相似文献
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《Molecular & general genetics : MGG》1998,258(1-2):78-88
The gene cluster (ery) governing the biosynthesis of the macrolide antibiotic erythromycin A by Saccharopolyspora erythraea contains, in addition to the eryA genes encoding the polyketide synthase, two regions containing genes for later steps in the pathway. The region 5′ of eryA that lies between the known genes ermE (encoding the erythromycin resistance methyltransferase) and eryBIII (encoding a putative S-adenosylmethionine-dependent methyltransferase), and that contains the gene eryBI (orf2), has now been sequenced. The inferred product of the eryBI gene shows striking sequence similarity to authentic β-glucosidases. Specific mutants were created in eryBI, and the resulting strains were found to synthesise erythromycin A, showing that this gene, despite its position in the biosynthetic
gene cluster, is not essential for erythromycin biosynthesis. A␣mutant in eryBIII and a double mutant in eryBI and eryBIII were obtained and the analysis of novel erythromycins produced by these strains confirmed the proposed function of EryBIII
as a C-methyltransferase. Also, a chromosomal mutant was constructed for the previously sequenced ORF19 and shown to accumulate
erythronolide B, as expected for an eryB mutant and consistent with its proposed role as an epimerase in dTDP-mycarose biosynthesis.
Received: 13 August 1997 / Accepted: 27 November 1997 相似文献
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The GH gene cluster in marmoset, Callithrix jacchus, comprises eight GH-like genes and pseudogenes and appears to have arisen as a consequence of gene duplications occurring
independently of those leading to the human GH gene cluster. We report here the complete sequence of the marmoset GH gene
locus, including the intergenic regions and 5′ and 3′ flanking sequence, and a study of the multiple GH-like genes of an additional
New World monkey (NWM), the white-fronted capuchin, Cebus albifrons. The marmoset sequence includes 945 nucleotides (nt) of 5′ flanking sequence and 1596 nt of 3′ flanking sequence that are
“unique”; between these are eight repeat units, including the eight GH genes/pseudogenes. The breakpoints between these repeats
are very similar, indicating a regular pattern of gene duplication. These breakpoints do not correspond to those found in
the much less regular human GH gene cluster. This and phylogenetic analysis of the repeat units within the marmoset gene cluster
strongly support the independent origin of these gene clusters, and the idea that the episode of rapid evolution that occurred
during GH evolution in primates preceded the gene duplications. The marmoset GH gene cluster also differs from that of human
in having fewer and more evenly distributed Alu sequences (a single pair in each repeat unit) and a “P-element” upstream of every gene/pseudogene. In human there is no P-element
upstream of the gene encoding pituitary GH, and these elements have been implicated in placental expression of the other genes
of the cluster. The GH gene clusters in marmoset and capuchin appear to have arisen as the consequence of a single-gene duplication
event, but in capuchin there was then a remarkable expansion of the GH locus, giving at least 40 GH-like genes and pseudogenes.
Thus even among NWMs the GH gene cluster is very variable.
[Reviewing Editor: Nicolas Galtier] 相似文献
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Listeria monocytogenes is a Gram-positive, facultative intracellular bacterium that causes invasive, often fatal, disease in susceptible hosts.
As a foodborne pathogen, the bacterium has emerged as a significant public health problem and has caused several epidemics
in the United States and Europe. Three serotypes (1/2a, 1/2b, 4b) of L. monocytogenes are responsible for nearly 95% of all reported cases of human listeriosis. L. monocytogenes serotype 4b has caused all well-characterized foodborne epidemic outbreaks in North America and Europe between 1981 and 1993.
However, most of the genetic studies to characterize virulence factors of L. monocytogenes have been done by using serotypes 1/2a and 1/2c. In this investigation, we examined three virulence-associated genes (hly encoding listeriolysin, plcA encoding phosphotidylinositol-specific phospholipase C, and inlA encoding internalin) of two serotype 4b and two serotype 1/2b strains. We chose these virulence-associated genes on the basis
of published sequence differences among strains from Listeria subgroups containing serotypes 1/2a and 1/2c versus 4b, respectively. They correspond to sequence homologies that include
very highly conserved (hlyA), highly conserved (plcA) and mostly conserved (inlA). We found by using nucleotide sequence analysis of the hly, plcA, and inlA genes, the two L. monocytogenes strains (including a strain associated with a foodborne disease outbreak in California in 1985) in this study, two serotype
1/2b strains from a study that we recently reported, and other similar published data for serotypes 1/2a, 1/2c, and 4b, had
a high degree of sequence conservation at the gene and protein levels for all three genes. However, the sequences for the
hly gene of L. monocytogenes strains of serotypes 1/2b and 4b were more closely related to each other and showed significant divergence from serotypes
1/2a and 1/2c. A unique nonsynonymous mutation was found in the hly gene of L. monocytogenes isolates that were associated with the 1985 California outbreak and were the epidemic phage type. When 158 L. monocytogenes isolates from the collection at the Centers for Disease Control and Prevention were screened, the mutation was found only
in one other strain that had been isolated in California 3 years before the epidemic. Although the California epidemic clone
was lactose negative, other L. monocytogenes serotype 4b isolates that were lactose negative did not possess the unique mutation observed in that epidemic clone.
Received: 18 June 1997 / Accepted: 4 December 1997 相似文献
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An ORF of 1716 nucleotides, putatively encoding a DNA polymerase, was characterized in the mitochondrial genome of the edible
basidiomycete Agrocybe aegerita. The complete gene, named Aa-polB, and its flanking regions were cloned and sequenced from three overlapping restriction fragments. Aa-polB is located between the SSU rDNA (5′ region) and a gene for tRNAAsn (3′ region), and is separated from these genes by two A+T-rich intergenic regions of 1048 (5′ region) and 3864 (3′ region)
nucleotides, which lack repeated sequences of mitochondrial or plasmid origin. The deduced Aa-POLB protein shows extensive
sequence similarity with the family B DNA polymerases encoded by genomes that rely on protein-primed replication (invertrons).
The domains involved in the 3′→5′ exonuclease (Exo I to III) and polymerase (Pol I to Pol V) activities were localized on
the basis of conserved sequence motifs. The alignment of the Aa-POLB protein (571 amino acids) with sequences of family B
DNA polymerases from invertrons revealed that in Aa-POLB the N-terminal region preceding Exo I is short, suggesting a close
relationship with the DNA polymerases of bacteriophages that have linear DNA. The Aa-polB gene was shown to be present in all wild strains examined, which were collected from a wide range of locations in Europe.
As shown by RT-PCR, the Aa-polB gene is transcribed in the mitochondria, at a low but significant level. The likelihood of the coexistence of Aa-POLB and
Pol γ in the A. aegerita mitochondrion is discussed in the light of recent reports showing the conservation of the nucleus-encoded Pol γ from yeast
to human.
Received: 13 October 1998 / Accepted: 21 December 1998 相似文献
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T Cox C Frazier J Tuttle S Flood L Yagi C T Yamashiro R Behari C Paszko R J Cano 《Journal of industrial microbiology & biotechnology》1998,21(3):167-174
The presence of Listeria monocytogenes as a dairy food contaminant is a lethal threat to dairy industrialists; therefore, products tainted with L. monocytogenes must be quickly detected and removed from production. This fluorogenic PCR-based assay was developed to rapidly detect L. monocytogenes contamination in dairy samples before a final product is distributed. The detection method employed uses a PCR primer pair
and a fluorogenic TaqMan probe which bind to a region of a virulence determinant gene specific to L. monocytogenes. As the DNA target is amplified, the 5′ nuclease activity of Taq DNA polymerase hydrolyzes the internal fluorogenic probe creating a change in fluorescence that can be monitored and automatically
analyzed with a fluorometer. Sensitivity studies indicated a lower detection limit of under 10 CFU for pure culture extracts
and spiked dairy enrichments. A study was performed on 266 dairy product samples obtained from Central California dairy production
plants. Eighty-three of these samples were artificially spiked with both high and low concentrations of L. monocytogenes before an overnight enrichment in TSB/LiCl/colostin sulfate/moxalactam media. DNA from enriched samples was obtained using
a rapid Chelex extraction specifically designed for dairy sample enrichments and automated analysis. The extraction was followed
by the fluorogenic PCR assay and measurement of fluorescence increase. The assay was completed within 24 h, with an observed
95.2% sensitivity, 96.7% specificity, 92.9% positive predictive value, 97.8% negative predictive value, and 96.2% accuracy.
According to specificity studies, five other bacterial species cross-reacted with the fluorogenic 5′ nuclease PCR. However,
only one of these strains (Listeria grayi) was able to grow in the enrichment medium employed, and was not isolated from any of the 266 dairy product enrichments evaluated
in this study. Therefore, this method provides a rapid, sensitive, and automatable analysis alternative to standard culture
techniques for the detection of Listeria monocytogenes in dairy samples.
Received 4 February 1998/ Accepted in revised form 1 October 1998 相似文献
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The ftsZ gene was cloned from the chromosomal DNA of Brevibacterium lactofermentum by the polymerase chain reaction (PCR) using two oligonucleotides designed from two conserved regions found in most of the
previously cloned and sequenced ftsZ genes from other microorganisms. ftsZ is a single-copy gene in corynebacteria and is located downstream from ftsQ and murC, indicating linkage between genes involved in peptidoglycan synthesis (mur genes) and genes involved in cell division (fts genes). The organisation of the cluster is similar to that in Streptomyces and different from those of Escherichia coli or Bacillus subtilis because ftsA is not located upstream of ftsZ. The gene was expressed in E. coli using the T7 expression system; the calculated molecular weight of the expressed protein was 50 kDa. Expression of the B. lactofermentum ftsZ gene in E. coli inhibited cell division and led to filamentation. The ftsZ gene of this organism does not complement ftsZ mutations or deletions in E. coli, when cloned on low or high-copy-number vectors.
Received: 14 January 1998 / Accepted: 31 March 1998 相似文献
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Entry of Listeria monocytogenes into hepatocytes requires expression of InIB, a surface protein of the internalin multigene family 总被引:19,自引:8,他引:19
Shaynoor Dramsi Indranil Biswas Emmanuelle Maguin Laurence Braun Pietro Mastroeni Pascale Cossart 《Molecular microbiology》1995,16(2):251-261
The intracellular bacterium Listeria monocytogenes can invade several types of normally non-phagocytic cells. Entry into cultured epithelial cells requires the expression of inIA, the first gene of an operon, comprising two genes: inIA, which encodes internalin, an 800-amino-acid protein, and inIB, which encodes a 630-amino-acid protein. Several genes homologous to inIA are detected in the genome of L. monocytogenes; InIB is one of them. We have assessed the role of inIB In invasiveness of L. monocytogenes by constructing isogenic chromosomal deletion mutants in the inIAB locus. Our findings indicate that: i) inIB is required for entry of L. monocytogenes into hepatocytes, but not into intestinal epithelial cells; ii) inIB encodes a surface protein; iii) internalin plays a role for entry into some hepatocyte cell lines. These results provide the first insight into the cell tropism displayed by L. monocytogenes. 相似文献