scholarly journals Molecular Basis of the Indole-Negative Reaction in Shigella Strains: Extensive Damages to the tna Operon by Insertion Sequences

2004 ◽  
Vol 186 (21) ◽  
pp. 7460-7465 ◽  
Author(s):  
Ferdousi Rezwan ◽  
Ruiting Lan ◽  
Peter R. Reeves
Keyword(s):  
Escherichia Coli ◽  
Molecular Basis ◽  
Insertion Sequence ◽  
Negative Reaction ◽  
Insertion Sequences ◽  
E Coli ◽  
Negative Phenotype

ABSTRACT The molecular basis of the loss of tryptophan utilization (indole-negative phenotype) of Shigella strains, in effect clones of Escherichia coli, was investigated. Analysis of the tna operon of 23 Shigella strains representing each of the indole-negative serotypes revealed that insertion sequence-mediated insertion and/or deletions damaged the tna operon, leading to inability to convert tryptophan to indole. These events differ for cluster 1, cluster 3, and the outlier Shigella strains, confirming our previous observation of independent origins of these lineages from within E. coli. Parallel loss of the trait and prevalence of indole-negative strains suggest that the trait is deleterious in Shigella strains and advantages those without it.

Antibiotic Resistance and Characteristics of Integrons in Escherichia coli Isolated from Penaeus vannamei at a Freshwater Shrimp Farm in Zhejiang Province, China

2019 ◽  
Vol 82 (3) ◽  
pp. 470-478 ◽  
Author(s):  
HUI CHENG ◽  
HAN JIANG ◽  
JIEHONG FANG ◽  
CHENG ZHU
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Insertion Sequence ◽  
Zhejiang Province ◽  
Resistant Bacteria ◽  
Penaeus Vannamei ◽  
Shrimp Farm ◽  
E Coli ◽  
Class 1 Integrons ◽  
Class 1

ABSTRACT Our study was conducted to investigate the antibiotic susceptibility profiles, integrons and their associated gene cassettes (GCs), and insertion sequence common regions of Escherichia coli isolates from Penaeus vannamei collected at a large-scale freshwater shrimp farm in Zhejiang Province, People's Republic of China. A total of 182 E. coli isolates were identified from 200 samples. With the exception of imipenem, isolates were most commonly resistant to β-lactams, followed by tetracylines and sulfonamides. Fifty-two (28.6%) E. coli isolates were classified as multidrug resistant, and the patterns were highly diverse, with 29 types represented. The multiple-antibiotic resistance indices of the isolates were 0.17 to 0.56; 9.3% (17) of the 182 isolates were positive for class 1 integrons, 0.5% (1 isolate) was positive for class 2 integrons, and an insertion sequence common region 1 element was found upstream of the intI1 (integrase) gene in one of the intI1-positive isolates. Four GC arrays were detected in class 1 integrons, and one GC array was detected in class 2 integrons. Although the overall prevalence of antimicrobial-resistant bacteria in P. vannamei was lower than that previously reported for poultry and livestock farms in China, concerns about the inappropriate use of antibiotics and the transmission of antimicrobial-resistant bacteria in aquaculture were raised. Alternative approaches to reducing or replacing the use of antibiotics should be further studied.

Determinants of β-lactam resistance in meningitis-causingEnterobacteriaceaein Brazil

2010 ◽  
Vol 56 (5) ◽  
pp. 399-407 ◽  
Author(s):  
L. N. Andrade ◽  
L. A.R. Minarini ◽  
A. Pitondo-Silva ◽  
E. C. Clímaco ◽  
I. C.V. Palazzo ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Insertion Sequence ◽  
Genetic Relationships ◽  
Mlst Database ◽  
High Genetic Diversity ◽  
Mlst Analysis ◽  
E Coli ◽  
Resistance Determinants ◽  
Class 1 ◽  
Encoding Genes

This study analyzed resistance determinants in extended-spectrum β-lactamase (ESBL)-producing enterobacteria and the epidemiology of 11 Escherichia coli isolates obtained from meningitis patients in a region of Brazil from 2000 to 2005. ESBL-encoding genes and their genetic environment were investigated by PCR and sequencing. The gene blaCTX-M-2was identified in 3 different enterobacteria (E. coli, Serratia marcescens , and Proteus mirabilis ) downstream of the insertion sequence ISCR1 (localized in class 1 integrons), but not as part of the resistance cassettes region. Multilocus sequence typing (MLST) was used to investigate genetic relationships between the 11 E. coli isolates in this study and strains associated with meningitis in the E. coli MLST database. MLST analysis indicated high genetic diversity among isolates, and no significant genetic relationship was identified with meningitis-causing E. coli in the database. The results in this report reinforce the need to be attentive to meningitis suspected to be due to ESBL-producing enterobacterial isolates, especially where ESBL epidemiology is well known.

scholarly journals Simultaneous Presence of Insertion Sequence Excision Enhancer and Insertion Sequence IS629Correlates with Increased Diversity and Virulence in Shiga Toxin-Producing Escherichia coli

2015 ◽  
Vol 53 (11) ◽  
pp. 3466-3473 ◽  
Author(s):  
M. Toro ◽  
L. V. Rump ◽  
G. Cao ◽  
J. Meng ◽  
E. W. Brown ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Insertion Sequence ◽  
Family Members ◽  
Simultaneous Presence ◽  
Content Type ◽  
E Coli ◽  
Genomic Deletions ◽  
Human Illness ◽  
Hostile Environments

Although new serotypes of enterohemorrhagicEscherichia coli(EHEC) emerge constantly, the mechanisms by which these new pathogens arise and the reasons emerging serotypes tend to carry more virulence genes than otherE. coliare not understood. An insertion sequence (IS) excision enhancer (IEE) was discovered in EHEC O157:H7 that promoted the excision of IS3family members and generating various genomic deletions. One IS3family member, IS629, actively transposes and proliferates in EHEC O157:H7 and enterotoxigenicE. coli(ETEC) O139 and O149. The simultaneous presence of the IEE and IS629(and other IS3family members) may be part of a system promoting not only adaptation and genome diversification inE. coliO157:H7 but also contributing to the development of pathogenicity among predominant serotypes. Prevalence comparisons of these elements in 461 strains, representing 72 different serotypes and 5 preassigned seropathotypes (SPT) A to E, showed that the presence of these two elements simultaneously was serotype specific and associated with highly pathogenic serotypes (O157 and top non-O157 Shiga toxin-producing Escherichia coli [STEC]) implicated in outbreaks and sporadic cases of human illness (SPT A and B). Serotypes lacking one or both elements were less likely to have been isolated from clinical cases. Our comparisons of IEE sequences showed sequence variations that could be divided into at least three clusters. Interestingly, the IEE sequences from O157 and the top 10 non-O157 STEC serotypes fell into clusters I and II, while less commonly isolated serotypes O5 and O174 fell into cluster III. These results suggest that IS629and IEE elements may be acting synergistically to promote genome plasticity and genetic diversity among STEC strains, enhancing their abilities to adapt to hostile environments and rapidly take up virulence factors.

scholarly journals The Bulged Nucleotide in the Escherichia coli Minimal Selenocysteine Insertion Sequence Participates in Interaction with SelB: a Genetic Approach

2000 ◽  
Vol 182 (22) ◽  
pp. 6302-6307 ◽  
Author(s):  
Chuang Li ◽  
Myriam Reches ◽  
Hanna Engelberg-Kulka
Keyword(s):  
Escherichia Coli ◽  
Insertion Sequence ◽  
Stop Codon ◽  
Loop Structure ◽  
Genetic Approach ◽  
Stem Loop ◽  
E Coli ◽  
Stem Loop Structure ◽  
Suppressor Mutations

ABSTRACT The UGA codon, which usually acts as a stop codon, can also direct the incorporation into a protein of the amino acid selenocysteine. This UGA decoding process requires acis-acting mRNA element called the selenocysteine insertion sequence (SECIS), which can form a stem-loop structure. InEscherichia coli, selenocysteine incorporation requires only the 17-nucleotide-long upper stem-loop structure of thefdhF SECIS. This structure carries a bulged nucleotide U at position 17. Here we asked whether the single bulged nucleotide located in the upper stem-loop structure of the E. coli fdhF SECIS is involved in the in vivo interaction with SelB. We used a genetic approach, generating and characterizingselB mutations that suppress mutations of the bulged nucleotide in the SECIS. All the selB suppressor mutations isolated were clustered in a region corresponding to 28 amino acids in the SelB C-terminal subdomain 4b. These selBsuppressor mutations were also found to suppress mutations in either the loop or the upper stem of the E. coli SECIS. Thus, the E. coli SECIS upper stem-loop structure can be considered a “single suppressible unit,” suggesting that there is some flexibility to the nature of the interaction between this element and SelB.

scholarly journals Genetic Characterization of Plasmid-mediated qepA Gene Among ESBL-producing Escherichia Coli Isolates in Mexico

2021 ◽  
Author(s):  
Humberto Barrios-Camacho ◽  
Josefina Duran-Bedolla ◽  
Jesus Silva-Sanchez ◽  
Luis Lozano-Aguirre ◽  
Fernando Reyna-Flores ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Molecular Characterization ◽  
Genetic Characterization ◽  
Insertion Sequences ◽  
Plasmid Sequence ◽  
E Coli ◽  
Multiple Copies ◽  
Chromosomal Mutations ◽  
Sequence Types

Abstract A molecular characterization of a plasmid-born qepA gene in (ESBL)-producing E. coli clinical isolates were performed. An 2.63% (11/418) were qepA positive isolates, of which a 90.0% carried CTX-M-15 (9/11) and SHV-12 (1/11). All isolates showed chromosomal mutations in the gyrA and parC genes. The clonal groups A, B and C were identified and belonged to, respectively, phylogroups A, B1 and D, as well as the sequence types 205, 405 and 617. Several plasmid profiles were determined with incompatibility groups FIA, FIB and FII. The genetic environment of the qepA in plasmid pEC8020 was different from those reported previously. The plasmid sequence included genes conferring resistance to β-lactams (blaCTX-M-15), macrolides (mphA), fluoroquinolones (qepA1), trimethoprim (dfrB4) and sulphonamides (sul1). Likewise, the IncF-pEC8020 plasmid carried several insertion sequences including ISCR3, IS6100 and multiple copies of IS26. This work contributes to the epidemiology and genetics of plasmid-born qepA genes of ESBL-producing E. coli.

scholarly journals IS103, a new insertion element in Escherichia coli: characterization and distribution in natural populations.

Genetics ◽  
1989 ◽  
Vol 121 (3) ◽  
pp. 423-431 ◽  
Author(s):  
B G Hall ◽  
L L Parker ◽  
P W Betts ◽  
R F DuBose ◽  
S A Sawyer ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Copy Number ◽  
Insertion Sequence ◽  
Natural Populations ◽  
Single Copy ◽  
Target Sequence ◽  
Wild Type ◽  
Insertion Element ◽  
E Coli ◽  
Natural Isolates

Abstract IS103 is a previously unknown insertion sequence found in Escherichia coli K12. We have sequenced IS103 and find that it is a 1441-bp element that consists of a 1395-bp core flanked by imperfect 23-bp inverted repeats. IS103 causes a 6-bp duplication of the target sequence into which it inserts. There is a single copy of IS103 present in wild-type E. coli K12 strain HfrC. In strain X342 and its descendents there are two additional copies, one of which is located within the bglF gene. IS103 is capable of excising from within bglF and restoring function of that gene. IS103 exhibits 44% sequence identity with IS3, suggesting that the two insertion sequences are probably derived from a common ancestor. We have examined the distribution of IS103 in the chromosomes and plasmids of the ECOR collection of natural isolates of E. coli. IS103 is found in 36 of the 71 strains examined, and it strongly tends to inhabit plasmids rather than chromosomes. Comparison of the observed distribution of IS103 with distributions predicted by nine different models for the regulation of transposition according to copy number and of the effects of copy number on fitness suggest that transposition of IS103 is strongly regulated and that it has only minor effects on fitness. The strong clustering of IS103 within one phylogenetic subgroup of the E. coli population despite its presence on plasmids suggests that plasmids tend to remain within closely related strains and that transfer to distantly related strains is inhibited.

scholarly journals Why do unrelated insertion sequences occur together in the genome of Escherichia coli?

Genetics ◽  
1988 ◽  
Vol 118 (3) ◽  
pp. 537-541
Author(s):  
D L Hartl ◽  
S A Sawyer
Keyword(s):  
Escherichia Coli ◽  
Horizontal Transfer ◽  
Process Model ◽  
Insertion Sequence ◽  
Branching Process ◽  
Insertion Sequences ◽  
Reference Collection ◽  
Natural Isolates ◽  
Positive Correlations

Abstract Natural isolates of Escherichia coli are polymorphic for the presence or absence of insertion sequences. Among the ECOR reference collection of 71 natural isolates studied for the number of copies of the insertion sequences IS1, IS2, IS3, IS4, IS5 and IS30, the number of strains containing no copies of the insertion sequences were 11, 28, 23, 43, 46 and 36, respectively. Significant correlations occur in the ECOR strains in the presence or absence of unrelated insertion sequences in the chromosome and plasmid complements. Strains containing any insertion sequence are more likely to contain additional, unrelated insertion sequences than would be expected by chance. We suggest that the positive correlations result from horizontal transfer mediated by plasmids. A branching-process model for the plasmid-mediated transmission of insertion sequences among hosts yields such a correlation, even in the absence of interactions affecting transposition or fitness. The predictions of the model are quantitatively in agreement with the observed correlations among insertion sequences.

scholarly journals Palindromic Unit-Independent Transposition of IS1397 in Yersinia pestis

2002 ◽  
Vol 184 (17) ◽  
pp. 4739-4746 ◽  
Author(s):  
Caroline Wilde ◽  
Sophie Bachellier ◽  
Maurice Hofnung ◽  
Elisabeth Carniel ◽  
Jean-Marie Clément
Keyword(s):  
Escherichia Coli ◽  
Yersinia Pestis ◽  
Hot Spots ◽  
Insertion Sequence ◽  
Host Protein ◽  
Its Sequence ◽  
E Coli ◽  
Specific Host ◽  
Target Dna ◽  
Direct Recognition

ABSTRACT Palindromic units (PUs) are intergenic repeated sequences scattered over the chromosomes of Escherichia coli and several other enterobacteria. In the latter, IS1397, an E. coli insertion sequence specific to PUs, transposes into PUs with sequences close to the E. coli consensus. Reasons for this insertion specificity can relate to either a direct recognition of the target (by its sequence or its structure) by the transposase or an interaction between a specific host protein and the PU target DNA sequence. In this study, we show that for Yersinia pestis, a species deprived of PUs, IS1397 can transpose onto its chromosome, with transpositional hot spots. Our results are in favor of a direct recognition of target DNA by IS1397 transposase.

scholarly journals Conjugative Interaction Induces Transposition of ISPst9 in Pseudomonas stutzeri AN10

2008 ◽  
Vol 191 (4) ◽  
pp. 1239-1247 ◽  
Author(s):  
J. A. Christie-Oleza ◽  
M. P. Lanfranconi ◽  
B. Nogales ◽  
J. Lalucat ◽  
R. Bosch
Keyword(s):  
Escherichia Coli ◽  
Dna Sequence ◽  
Insertion Sequence ◽  
Genetic Material ◽  
Pseudomonas Stutzeri ◽  
E Coli ◽  
Double Stranded Dna ◽  
Circle Formation ◽  
Flanking Regions ◽  
Kinetics Of

ABSTRACT ISPst9 is an ISL3-like insertion sequence (IS) that was recently described in the naphthalene-degrading organism Pseudomonas stutzeri strain AN10. In this paper we describe a novel strong IS regulation stimulus; transposition of ISPst9 is induced in all P. stutzeri AN10 cells after conjugative interaction with Escherichia coli. Thus, we observed that in all P. stutzeri AN10 cells that received genetic material by conjugation the ISPst9 genomic dose and/or distribution was changed. Furthermore, ISPst9 transposition was also observed when P. stutzeri AN10 cells were put in contact with the plasmidless conjugative strain E. coli S17-1λ pir , but not when they were put in contact with E. coli DH5α (a nonconjugative strain). The mechanism of ISPst9 transposition was analyzed, and transposition was shown to proceed by excision from the donor DNA using a conservative mechanism, which generated 3- to 10-bp deletions of the flanking DNA. Our results indicate that ISPst9 transposes, forming double-stranded DNA circular intermediates consisting of the IS and a 5-bp intervening DNA sequence probably derived from the ISPst9 flanking regions. The kinetics of IS circle formation are also described.

scholarly journals Genome rearrangements induce biofilm formation in Escherichia coli C – an old model organism with a new application in biofilm research

BMC Genomics ◽  
2019 ◽  
Vol 20 (1) ◽  
Author(s):  
Jarosław E. Król ◽  
Donald C. Hall ◽  
Sergey Balashov ◽  
Steven Pastor ◽  
Justin Sibert ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Insertion Sequence ◽  
Genomic Sequence ◽  
Model Organism ◽  
Start Codon ◽  
Bacterial Survival ◽  
E Coli ◽  
Full Genomic Sequence

Abstract Background Escherichia coli C forms more robust biofilms than other laboratory strains. Biofilm formation and cell aggregation under a high shear force depend on temperature and salt concentrations. It is the last of five E. coli strains (C, K12, B, W, Crooks) designated as safe for laboratory purposes whose genome has not been sequenced. Results Here we present the complete genomic sequence of this strain in which we utilized both long-read PacBio-based sequencing and high resolution optical mapping to confirm a large inversion in comparison to the other laboratory strains. Notably, DNA sequence comparison revealed the absence of several genes thought to be involved in biofilm formation, including antigen 43, waaSBOJYZUL for lipopolysaccharide (LPS) synthesis, and cpsB for curli synthesis. The first main difference we identified that likely affects biofilm formation is the presence of an IS3-like insertion sequence in front of the carbon storage regulator csrA gene. This insertion is located 86 bp upstream of the csrA start codon inside the − 35 region of P4 promoter and blocks the transcription from the sigma32 and sigma70 promoters P1-P3 located further upstream. The second is the presence of an IS5/IS1182 in front of the csgD gene. And finally, E. coli C encodes an additional sigma70 subunit driven by the same IS3-like insertion sequence. Promoter analyses using GFP gene fusions provided insights into understanding this regulatory pathway in E. coli. Conclusions Biofilms are crucial for bacterial survival, adaptation, and dissemination in natural, industrial, and medical environments. Most laboratory strains of E. coli grown for decades in vitro have evolved and lost their ability to form biofilm, while environmental isolates that can cause infections and diseases are not safe to work with. Here, we show that the historic laboratory strain of E. coli C produces a robust biofilm and can be used as a model organism for multicellular bacterial research. Furthermore, we ascertained the full genomic sequence of this classic strain, which provides for a base level of characterization and makes it useful for many biofilm-based applications.

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