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.

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.

Utilization of chymotrypsin as a sole carbon and (or) nitrogen source by Escherichia coli

1992 ◽  
Vol 38 (4) ◽  
pp. 290-295 ◽  
Author(s):  
Arthur S. Brecher ◽  
Timothy A. Moehlman ◽  
William D. Hann
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Nitrogen Source ◽  
Degradation Products ◽  
Defined Medium ◽  
Host Protein ◽  
Mammalian Host ◽  
Sole Nitrogen Source ◽  
E Coli ◽  
Nitrogen Nutrients

α-Chymotrypsin serves as a sole carbon source, sole nitrogen source, and as sole carbon plus nitrogen source for wild-type Escherichia coli in a totally defined medium. Hence, a mammalian host for E. coli may supply the necessary carbon and nitrogen nutrients for the microorganism. Growth is most rapid when chymotrypsin is a sole nitrogen source,and least rapid with chymotrypsin as a carbon source. The approximate doubling times for E. coli utilizing chymotrypsin as a nitrogen source, carbon plus nitrogen source, and carbon source are 1.6, 4.6, and 11.3 h, respectively. The activity of the residual enzyme in the culture supernates falls off asymptotically over the course of time, as followed by cleavage of glutaryl-L-phenylalanine-p-nitroanilide. Chymotrypsin hydrolyzes succinyl-L-ala-L-ala-L-ala-p-nitroanilide, the elastase substrate, to some extent. Peptidases do not appear to be secreted that hydrolyze such model substrates as benzoyl-DL-arginine-p-nitroanilide, the tryptic and cathepsin B substrate, L-leucine-p-nitroanilide, the leucine aminopeptidase substrate, or L-lysine-p-nitroanilide, the aminopeptidase B substrate. Growth of E. coli is generally directly related to the loss of chymotryptic activity in the medium. Hence, autolysis of chymotrypsin, i.e., self-degradation, is an important factor for the availability of degradation products of the enzyme to the bacterium for growth purposes. Accordingly, the degradation of a host protein by autolysis presents an opportunity for E. coli to survive during periods of host nutritional crisis by utilization of the degradation peptides that are produced during autolysis. Key words: chymotrypsin, Escherichia coli, growth, nutrition, peptide source.

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 pH 6 Antigen Is an Antiphagocytic Factor Produced by Yersinia pestis Independent of Yersinia Outer Proteins and Capsule Antigen

2004 ◽  
Vol 72 (12) ◽  
pp. 7212-7219 ◽  
Author(s):  
Xiao-Zhe Huang ◽  
Luther E. Lindler
Keyword(s):  
Escherichia Coli ◽  
Yersinia Pestis ◽  
Intracellular Bacteria ◽  
Mouse Macrophage ◽  
Host Cell Line ◽  
E Coli ◽  
Significant Difference ◽  
Mouse Macrophages ◽  
Isogenic Strains ◽  
Raw264.7 Macrophage

ABSTRACT The pH 6 antigen (pH 6 Ag; PsaA) of Yersinia pestis has been shown to be a virulence factor. In this study, we set out to investigate the possible function of Y. pestis PsaA in a host cell line, RAW264.7 mouse macrophages, in order to better understand the role it might play in virulence. Y. pestis KIM5 derivatives with and without the pCD1 plasmid and their psaA isogenic counterparts and Escherichia coli HB101 and DΗ5α carrying a psaA clone or a vector control were used for macrophage infections. Macrophage-related bacteria and gentamicin-resistant intracellular bacteria generated from plate counting and direct microscopic examinations were used to evaluate these RAW264.7 macrophage infections. Y. pestis psaA isogenic strains did not show any significant difference in their abilities to associate with or bind to mouse macrophage cells. However, expression of psaA appeared to significantly reduce phagocytosis of both Y. pestis and E. coli by mouse macrophages (P < 0.05). Furthermore, we found that complementation of psaA mutant Y. pestis strains could completely restore the ability of the bacteria to resist phagocytosis. Fluorescence microscopy following differential labeling of intracellular and extracellular Y. pestis revealed that significantly lower numbers of psaA-expressing bacteria were located inside the macrophages. Enhanced phagocytosis resistance was specific for bacteria expressing psaA and did not influence the ability of the macrophages to engulf other bacteria. Our data demonstrate that Y. pestis pH 6 Ag does not enhance adhesion to mouse macrophages but rather promotes resistance to phagocytosis.

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 Molecular Characterization of IS1541Insertions in the Genome of Yersinia pestis

1998 ◽  
Vol 180 (1) ◽  
pp. 178-181 ◽  
Author(s):  
Monique Odaert ◽  
Annie Devalckenaere ◽  
Patrick Trieu-Cuot ◽  
Michel Simonet
Keyword(s):  
Yersinia Pestis ◽  
Hot Spots ◽  
Insertion Sequence ◽  
Single Copy ◽  
Open Reading Frames ◽  
Stem Loop ◽  
Insertion Sites ◽  
Flanking Regions ◽  
Reading Frames

ABSTRACT The genome of Yersinia pestis, the causative agent of plague, contains at least 30 copies of an element, designated IS1541, which is structurally related to IS200(85% identity). One such element is inserted within the chromosomalinv gene (M. Simonet, B. Riot, N. Fortineau, and P. Berche, Infect. Immun. 64:375–379, 1996). We characterized other IS1541 insertions by cloning 14 different Y. pestis 6/69M loci carrying a single copy of this insertion sequence (IS) into Escherichia coli and, for each element, sequencing 250 bp of both flanking regions. In no case was this IS element inserted into large open reading frames; however, in eight cases, it was detected downstream (17 to 139 bp) of genes thought to be transcribed monocistronically or which constituted the last gene of an operon, and in only one case was it detected upstream (37 bp) of the first gene of an operon. Sequence analysis revealed stem-loop structures (ΔG, <−10 kcal) resembling rho-independent transcription terminators in 8 of the 14 insertion sites. These motifs might constitute hot spots for insertion of this IS1541element within the Y. pestis genome.

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 Sequence Analysis of Tn10 Insertion Sites in a Collection of Escherichia coli Strains Used for Genetic Mapping and Strain Construction

1998 ◽  
Vol 180 (23) ◽  
pp. 6408-6411 ◽  
Author(s):  
Brian P. Nichols ◽  
Obaid Shafiq ◽  
Victoria Meiners
Keyword(s):  
Escherichia Coli ◽  
Sequence Analysis ◽  
Hot Spots ◽  
Insertion Site ◽  
Inverse Pcr ◽  
E Coli ◽  
Chromosome Sequence ◽  
Tn10 Insertion ◽  
Insertion Sites ◽  
Recombination Hot Spots

ABSTRACT The chromosomal insertion sites of Tn10-containingEscherichia coli strains were amplified by inverse PCR, and the nucleotide sequences of the junctions were determined. In 95 strains analyzed, 88 unique Tn10 positions were determined and matched to the E. coli chromosome sequence. Two gaps in insertion site positions were noted, one including the terminus of DNA replication and another bounded by recombination hot spots RhsA and RhsB.

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