scholarly journals Chromosomal location of att P7, the recA-independent p7 integration site used in the suppression of Escherichia coli dnaA mutations.

1982 ◽  
Vol 150 (3) ◽  
pp. 1400-1404 ◽  
Author(s):  
R H Chesney ◽  
E Adler
Keyword(s):  
Escherichia Coli ◽  
Chromosomal Location ◽  
Integration Site

scholarly journals Bacteriophage Lambda: a Paradigm Revisited

2010 ◽  
Vol 84 (13) ◽  
pp. 6876-6879 ◽  
Author(s):  
Paul C. M. Fogg ◽  
Heather E. Allison ◽  
Jon R. Saunders ◽  
Alan J. McCarthy
Keyword(s):  
Escherichia Coli ◽  
Sequence Analysis ◽  
High Frequency ◽  
Southern Hybridization ◽  
Integration Site ◽  
Bacteriophage Lambda ◽  
Rare Event ◽  
Low Frequency ◽  
E Coli ◽  
Very Low Frequency

ABSTRACT Bacteriophage lambda has an archetypal immunity system, which prevents the superinfection of its Escherichia coli lysogens. It is now known that superinfection can occur with toxigenic lambda-like phages at a high frequency, and here we demonstrate that the superinfection of a lambda lysogen can lead to the acquisition of additional lambda genomes, which was confirmed by Southern hybridization and quantitative PCR. As many as eight integration events were observed but at a very low frequency (6.4 × 10−4) and always as multiple insertions at the established primary integration site in E. coli. Sequence analysis of the complete immunity region demonstrated that these multiply infected lysogens were not immunity mutants. In conclusion, although lambda superinfection immunity can be confounded, it is a rare event.

Excision and transposition of Tn5 upon insertion in the hha gene of Escherichia coli

1994 ◽  
Vol 40 (7) ◽  
pp. 597-601 ◽  
Author(s):  
C. Badenas ◽  
C. Madrid ◽  
A. Juárez
Keyword(s):  
Escherichia Coli ◽  
High Frequency ◽  
Chromosomal Location ◽  
Single Copy

We report the occurrence of Tn5 secondary transpositions in Escherichia coli HB101 hha::Tn5(pANN202-312). Tn5-induced hha mutants (hemolysin oveiproducers) segregated at high frequency either hemolysin-negative clones or clones showing the parental hemolytic phenotype (reduced hemolysin production). Secondary transpositions of Tn5 appeared to be responsible for the phenotypes of both types of derivatives. The hemolysin-negative clones no longer harboured Tn5 in the hha gene, but rather Tn5 was in the hly genes of the hemolytic plasmid pANN202-312. The derivatives that recovered the parental hemolytic phenotype contained a single copy of Tn5 in a chromosomal location different from that of hha. Both kinds of transpositional events appeared to restore the function of the hha gene.Key words: Tn5, transposition, Escherichia coli, excision.

Resistance to piperacillin/tazobactam in Escherichia coli resulting from extensive IS26-associated gene amplification of blaTEM-1

2019 ◽  
Vol 74 (11) ◽  
pp. 3179-3183 ◽  
Author(s):  
Katrine Hartung Hansen ◽  
Minna Rud Andreasen ◽  
Martin Schou Pedersen ◽  
Henrik Westh ◽  
Lotte Jelsbak ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Amplification ◽  
Copy Number ◽  
Chromosomal Location ◽  
Sequencing Data ◽  
Pcr Screening ◽  
E Coli ◽  
Oxford Nanopore ◽  
Additional Strain ◽  
Resistance To Penicillin

Abstract Background bla TEM-1 encodes a narrow-spectrum β-lactamase that is inhibited by β-lactamase inhibitors and commonly present in Escherichia coli. Hyperproduction of blaTEM-1 may cause resistance to penicillin/β-lactamase inhibitor (P/BLI) combinations. Objectives To characterize EC78, an E. coli bloodstream isolate, resistant to P/BLI combinations, which contains extensive amplification of blaTEM-1 within the chromosome. Methods EC78 was sequenced using Illumina and Oxford Nanopore Technology (ONT) methodology. Configuration of blaTEM-1 amplification was probed using PCR. Expression of blaTEM-1 mRNA was determined using quantitative PCR and β-lactamase activity was determined spectrophotometrically in a nitrocefin conversion assay. Growth rate was assessed to determine fitness and stability of the gene amplification was assessed by passage in the absence of antibiotics. Results Illumina sequencing of EC78 identified blaTEM-1B as the only acquired β-lactamase preceded by the WT P3 promoter and present at a copy number of 182.6 with blaTEM-1B bracketed by IS26 elements. The chromosomal location of the IS26-blaTEM-1B amplification was confirmed by ONT sequencing. Hyperproduction of blaTEM-1 was confirmed by increased transcription of blaTEM-1 and β-lactamase activity and associated with a significant fitness cost; however, the array was maintained at a relatively high copy number for 150 generations. PCR screening for blaTEM amplification of isolates resistant to P/BLI combinations identified an additional strain containing an IS26-associated amplification of a blaTEM gene. Conclusions IS26-associated amplification of blaTEM can cause resistance to P/BLI combinations. This adaptive mechanism of resistance may be overlooked if simple methods of genotypic prediction (e.g. gene presence/absence) are used to predict antimicrobial susceptibility from sequencing data.

scholarly journals Development of a New Integration Site within theBacillus subtilis Chromosome and Construction of Compatible Expression Cassettes

2001 ◽  
Vol 183 (8) ◽  
pp. 2696-2699 ◽  
Author(s):  
Barbara Härtl ◽  
Wolfgang Wehrl ◽  
Thomas Wiegert ◽  
Georg Homuth ◽  
Wolfgang Schumann
Keyword(s):  
Dna Sequences ◽  
Chromosomal Location ◽  
Integration Site ◽  
Regulatory Gene ◽  
Expression Vectors ◽  
Transcriptional Fusion ◽  
Gene Coding ◽  
Regulated Expression ◽  
Subtilis Chromosome ◽  
Integration Sites

ABSTRACT The Bacillus subtilis lacA gene, coding for β-galactosidase, has been explored as a new site able to accept DNA sequences from nonreplicating delivery vectors. Two such delivery expression vectors have been constructed and shown to be useful in obtaining regulated expression from the chromosomal location. In another experiment, it was shown that the integration of a regulatory gene at the lacA locus was able to control the expression of a transcriptional fusion at the amyElocus. These experiments demonstrate that both integration sites can be used simultaneously to obtain regulated expression of desired genes.

Chromosomal location of gene governing the trehalose utilization in Escherichia coli K12

1977 ◽  
Vol 152 (1) ◽  
pp. 105-108 ◽  
Author(s):  
L. Becerra de Lares ◽  
J. Ratouchniak ◽  
F. Casse
Keyword(s):  
Escherichia Coli ◽  
Chromosomal Location ◽  
Escherichia Coli K12

scholarly journals Chromosomal location of a mutation causing chloramphenicol resistance in Escherichia coli K 12

1968 ◽  
Vol 11 (1) ◽  
pp. 97-104 ◽  
Author(s):  
E. C. R. Reeve ◽  
D. R. Suttie
Keyword(s):  
Escherichia Coli ◽  
Gene Order ◽  
Chromosomal Location ◽  
Attachment Site ◽  
Chloramphenicol Resistance ◽  
K 12 ◽  
Resistant Mutation

A chloramphenicol-resistant mutation in Escherichia coli K 12, cmlA1 (previously designated 1a), giving a higher Cm-resistance than other mutations yet examined, has been shown to have a chromosomal location, the gene order being gal, λ, bio, cmlA, pyrD. CmlA can be transduced efficiently into cm-sensitive strains by P1 with little phenotypic lag, and is co-transduced with the λ-attachment site (frequency 1·13%) but not with gal or pyrD.

scholarly journals Recycling of Shiga Toxin 2 Genes in Sorbitol-Fermenting Enterohemorrhagic Escherichia coli O157:NM

2007 ◽  
Vol 74 (1) ◽  
pp. 67-72 ◽  
Author(s):  
Alexander Mellmann ◽  
Shan Lu ◽  
Helge Karch ◽  
Jian-guo Xu ◽  
Dag Harmsen ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Integration Site ◽  
Hot Spot ◽  
Blot Hybridization ◽  
Enterohemorrhagic Escherichia Coli ◽  
Biologically Active ◽  
E Coli ◽  
Shiga Toxin 2

ABSTRACT Using colony blot hybridization with stx 2 and eae probes and agglutination in anti-O157 lipopolysaccharide serum, we isolated stx 2-positive and eae-positive sorbitol-fermenting (SF) enterohemorrhagic Escherichia coli (EHEC) O157:NM (nonmotile) strains from initial stool specimens and stx-negative and eae-positive SF E. coli O157:NM strains from follow-up specimens (collected 3 to 8 days later) from three children. The stx-negative isolates from each patient shared with the corresponding stx 2-positive isolates fliC H7, non-stx virulence traits, and multilocus sequence types, which indicates that they arose from the stx 2-positive strains by loss of stx 2 during infection. Analysis of the integrity of the yecE gene, a possible stx phage integration site in EHEC O157, in the consecutive stx 2-positive and stx-negative isolates demonstrated that yecE was occupied in stx 2-positive but intact in stx-negative strains. It was possible to infect and lysogenize the stx-negative E. coli O157 strains in vitro using an stx 2-harboring bacteriophage from one of the SF EHEC O157:NM isolates. The acquisition of the stx 2-containing phage resulted in the occupation of yecE and production of biologically active Shiga toxin 2. We conclude that the yecE gene in SF E. coli O157:NM is a hot spot for excision and integration of Shiga toxin 2-encoding bacteriophages. SF EHEC O157:NM strains and their stx-negative derivatives thus represent a highly dynamic system that can convert in both directions by the loss and gain of stx 2-harboring phages. The ability to recycle stx 2, a critical virulence trait, makes SF E. coli O157:NM strains ephemeral EHEC that can exist as stx-negative variants during certain phases of their life cycle.

scholarly journals Characterization of Shiga Toxin 2a Encoding Bacteriophages Isolated From High-Virulent O145:H25 Shiga Toxin-Producing Escherichia coli

2021 ◽  
Vol 12 ◽  
Author(s):  
Silje N. Ramstad ◽  
Yngvild Wasteson ◽  
Bjørn-Arne Lindstedt ◽  
Arne M. Taxt ◽  
Jørgen V. Bjørnholt ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Integration Site ◽  
Severe Disease ◽  
High Sequence Identity ◽  
Shiga Toxins ◽  
Sequence Identity ◽  
Diarrhea Case ◽  
The Usa ◽  
Uremic Syndrome

Shiga toxin-producing Escherichia coli (STEC) may cause severe disease mainly due to the ability to produce Shiga toxins (Stx) encoded on bacteriophages. In Norway, more than 30% of the reported cases with STEC O145:H25 develop hemolytic uremic syndrome (HUS), and most cases, with known travel history, acquired the infection domestically. To describe phage characteristics associated with high virulence, we extracted the Stx2a phage sequences from eight clinical Norwegian O145:H25 STEC to conduct in-depth molecular characterization using long and short read sequencing. The Stx2a phages were annotated, characterized, and compared with previously published Stx2a phages isolated from STEC of different serotypes. The Norwegian O145:H25 Stx2a phages showed high sequence identity (>99%) with 100% coverage. The Stx2a phages were located at the integration site yciD, were approximately 45 kbp long, and harbored several virulence-associated genes, in addition to stx2a, such as nanS and nleC. We observed high sequence identity (>98%) and coverage (≥94%) between Norwegian O145:H25 Stx2a phages and publicly available Stx2a phages from O145:H25 and O145:H28 STEC, isolated from HUS cases in the USA and a hemorrhagic diarrhea case from Japan, respectively. However, low similarity was seen when comparing the Norwegian O145:H25 Stx2a phage to Stx2a phages from STEC of other serotypes. In all the Norwegian O145:H25 STEC, we identified a second phage or remnants of a phage (a shadow phage, 61 kbp) inserted at the same integration site as the Stx2a phage. The shadow phage shared similarity with the Stx2a phage, but lacked stx2a and harbored effector genes not present in the Stx2a phage. We identified a conserved Stx2a phage among the Norwegian O145:H25 STEC that shared integration site with a shadow phage in all isolates. Both phage and shadow phage harbored several virulence-associated genes that may contribute to the increased pathogenicity of O145:H25 STEC.

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