scholarly journals Myths and mechanisms: RecBCD and Chi hotspots as determinants of self vs. non-self

2021 ◽  
Author(s):  
Suriyen Subramaniam ◽  
Gerald R Smith
Keyword(s):  
Escherichia Coli ◽  
Nucleotide Sequence ◽  
Related Species ◽  
High Frequency ◽  
Phage Infection ◽  
Self Determination ◽  
Wide Spread ◽  
Genomic Position ◽  
E Coli ◽  
New Genes

Bacteria face a challenge when DNA enters their cells by transformation, mating, or phage infection. Should they treat this DNA as an invasive foreigner and destroy it, or consider it one of their own and potentially benefit from incorporating new genes or alleles to gain useful functions? It is frequently stated that the short nucleotide sequence Chi (5' GCTGGTGG 3') recognized by RecBCD helicase-nuclease allows Escherichia coli to distinguish self (i.e., E. coli) DNA from non-self (i.e., any other) DNA and to destroy non-self DNA, and that Chi is 'overrepresented' in the E. coli genome. We show here that these dogmas are incorrect and apparently based on false assumptions. We note Chi's wide-spread occurrence and activity in distantly related species. We illustrate multiple, highly non-random features of the genomes of E. coli and coliphage P1 that account for Chi's high frequency and genomic position, leading us to propose that P1 selects for Chi's enhancement of recombination, whereas E. coli selects for the preferred codons in Chi. We discuss other, substantiated mechanisms for self vs. non-self determination involving RecBCD and for RecBCD's destruction of DNA that cannot recombine, whether foreign or domestic.

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.

scholarly journals Genome-wide comparison of phage M13-infected vs. uninfectedEscherichia coli

2005 ◽  
Vol 51 (1) ◽  
pp. 29-35 ◽  
Author(s):  
Fredrik Karlsson ◽  
Ann-Christin Malmborg-Hager ◽  
Ann-Sofie Albrekt ◽  
Carl A.K Borrebaeck
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Acid Stress ◽  
Phage Infection ◽  
Transcriptional Analysis ◽  
Filamentous Phage ◽  
Phosphotransferase System ◽  
E Coli ◽  
Genome Wide

To identify Escherichia coli genes potentially regulated by filamentous phage infection, we used oligonucleotide microarrays. Genome-wide comparison of phage M13-infected and uninfected E. coli, 2 and 20 min after infection, was performed. The analysis revealed altered transcription levels of 12 E. coli genes in response to phage infection, and the observed regulation of phage genes correlated with the known in vivo pattern of M13 mRNA species. Ten of the 12 host genes affected could be grouped into 3 different categories based on cellular function, suggesting a coordinated response. The significantly upregulated genes encode proteins involved in reactions of the energy-generating phosphotransferase system and transcription processing, which could be related to phage transcription. No genes belonging to any known E. coli stress response pathways were scored as upregulated. Furthermore, phage infection led to significant downregulation of transcripts of the bacterial genes gadA, gadB, hdeA, gadE, slp, and crl. These downregulated genes are normally part of the host stress response mechanisms that protect the bacterium during conditions of acid stress and stationary phase transition. The phage-infected cells demonstrated impaired function of the oxidative and the glutamate-dependent acid resistance systems. Thus, global transcriptional analysis and functional analysis revealed previously unknown host responses to filamentous phage infection.Key words: filamentous phage infection, global transcriptional analysis, AR, Escherichia coli.

scholarly journals Occurrence of Virulence Genes Associated with Diarrheagenic Pathotypes in Escherichia coli Isolates from Surface Water

2012 ◽  
Vol 79 (1) ◽  
pp. 328-335 ◽  
Author(s):  
Jatinder P. S. Sidhu ◽  
Warish Ahmed ◽  
Leonie Hodgers ◽  
Simon Toze
Keyword(s):  
Escherichia Coli ◽  
Health Risks ◽  
High Frequency ◽  
Aquatic Ecosystems ◽  
Virulence Genes ◽  
Storm Water ◽  
Storm Events ◽  
Widespread Occurrence ◽  
Content Type ◽  
E Coli

ABSTRACTEscherichia coliisolates (n= 300) collected from six sites in subtropical Brisbane, Australia, prior to and after storm events were tested for the presence of 11 virulence genes (VGs) specific to diarrheagenic pathotypes. The presence ofeaeA,stx1,stx2, andehxAgenes specific for the enterohemorrhagicE. coli(EHEC) pathotype was detected in 56%, 6%, 10%, and 13% of isolates, respectively. The VGsastA(69%) andaggR(29%), carried by enteroaggregative (EAEC) pathotypes, were frequently detected inE. coliisolates. The enteropathogenicE. coli(EPEC) genebfpwas detected in 24% of isolates. In addition, enteroinvasiveE. coli(EIEC) VGipaHwas also detected in 14% of isolates. During dry periods, isolates belonging to the EAEC pathotype were most commonly detected (23%), followed by EHEC (11%) and EPEC (11%). Conversely, a more uniform prevalence of pathotypes, EPEC (14%), EAEC (12%), EIEC (10%), EHEC (7%), and ETEC (7%), was observed after the storm events. The results of this study highlight the widespread occurrence of potentially diarrheagenic pathotypes in the urban aquatic ecosystems. While the presence of VGs inE. coliisolates alone is insufficient to determine pathogenicity, the presence of diarrheagenicE. colipathotypes in high frequency after the storm events could lead to increased health risks if untreated storm water were to be used for nonpotable purposes and recreational activities.

scholarly journals Yersinia pseudotuberculosis Produces a Cytotoxic Necrotizing Factor

2002 ◽  
Vol 70 (5) ◽  
pp. 2708-2714 ◽  
Author(s):  
Hank A. Lockman ◽  
Rebecca A. Gillespie ◽  
Beth D. Baker ◽  
Elizabeth Shakhnovich
Keyword(s):  
Escherichia Coli ◽  
Nucleotide Sequence ◽  
Yersinia Pseudotuberculosis ◽  
Virulence Plasmid ◽  
E Coli ◽  
Cytotoxic Necrotizing Factor ◽  
Cell Extracts

ABSTRACT Cell extracts from Yersinia pseudotuberculosis induced multinucleation in HEp-2 cells in a manner similar to the effect caused by Escherichia coli cytotoxic necrotizing factor (CNF). The activity was not dependent on the Yersinia 70-kb virulence plasmid, and the activity was not inhibited by antibodies capable of neutralizing E. coli CNF type 1. The nucleotide sequence of the Yersinia cnf gene was 65.1% identical to the E. coli cnf gene.

scholarly journals High Frequency of Diarrheagenic Escherichia coli in HIV-Infected Patients and Patients with Thalassemia in Kerman, Iran

2015 ◽  
Vol 16 (4) ◽  
pp. 353-358 ◽  
Author(s):  
Hesam Alizade ◽  
Hamid Sharifi ◽  
Zahedeh Naderi ◽  
Reza Ghanbarpour ◽  
Mehdi Bamorovat ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Polymerase Chain Reaction ◽  
Statistical Analysis ◽  
High Frequency ◽  
Multiplex Polymerase Chain Reaction ◽  
Chain Reaction ◽  
Fecal Samples ◽  
E Coli ◽  
Diarrheagenic Escherichia Coli ◽  
Polymerase Chain

This study was conducted on patients with thalassemia and HIV-infected patients to determine the frequency of diarrheagenic Escherichia coli in Kerman, Iran. We analyzed 68 and 49 E coli isolates isolated from healthy fecal samples of patients with thalassemia and HIV-infected patients, respectively. The E coli isolates were studied using a multiplex polymerase chain reaction to identify the enterotoxigenic E coli (ETEC), enterohemorrhagic E coli (EHEC), and enteropathogenic E coli (EPEC) groups. Statistical analysis was carried out to determine the correlation of diarrheagenic E coli between HIV-infected patients and patients with thalassemia using Stata 11.2 software. The frequency of having at least 1 diarrheagenic E coli was more common in patients with thalassemia (67.64%) than in HIV-infected patients (57.14%; P = .25), including ETEC (67.64% versus 57.14%), EHEC (33.82% versus 26.53%), and EPEC (19.11% versus 16.32%). The results of this study indicate that ETEC, EHEC, and EPEC pathotypes are widespread among diarrheagenic E coli isolates in patients with thalassemia and HIV-infected patients.

scholarly journals Characteristics of a New Enantioselective Thermostable Dipeptidase from Brevibacillus borstelensis BCS-1 and Its Application to Synthesis of a d-Amino-Acid-Containing Dipeptide

2004 ◽  
Vol 70 (3) ◽  
pp. 1570-1575 ◽  
Author(s):  
Dae Heoun Baek ◽  
Jae Jun Song ◽  
Seok-Joon Kwon ◽  
Chung Park ◽  
Chang-Min Jung ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Nucleotide Sequence ◽  
Amino Acid Sequence ◽  
Open Reading Frame ◽  
Nucleotide Sequence Analysis ◽  
Reading Frame ◽  
E Coli ◽  
Specificity Constant ◽  
Optimal Ph

ABSTRACT A new thermostable dipeptidase gene was cloned from the thermophile Brevibacillus borstelensis BCS-1 by genetic complementation of the d-Glu auxotroph Escherichia coli WM335 on a plate containing d-Ala-d-Glu. Nucleotide sequence analysis revealed that the gene included an open reading frame coding for a 307-amino-acid sequence with an M r of 35,000. The deduced amino acid sequence of the dipeptidase exhibited 52% similarity with the dipeptidase from Listeria monocytogenes. The enzyme was purified to homogeneity from recombinant E. coli WM335 harboring the dipeptidase gene from B. borstelensis BCS-1. Investigation of the enantioselectivity (E) to the P1 and P1′ site of Ala-Ala revealed that the ratio of the specificity constant (k cat /Km ) for l-enantioselectivity to the P1 site of Ala-Ala was 23.4 � 2.2 [E = (k cat /Km ) l,d /(k cat /Km ) d,d ], while the d-enantioselectivity to the P1′ site of Ala-Ala was 16.4 � 0.5 [E = (k cat /Km ) l,d /(k cat /Km ) l,l ] at 55�C. The enzyme was stable up to 55�C, and the optimal pH and temperature were 8.5 and 65�C, respectively. The enzyme was able to hydrolyze l-Asp-d-Ala, l-Asp-d-AlaOMe, Z-d-Ala-d-AlaOBzl, and Z-l-Asp-d-AlaOBzl, yet it could not hydrolyze d-Ala-l-Asp, d-Ala-l-Ala, d-AlaNH2, and l-AlaNH2. The enzyme also exhibited β-lactamase activity similar to that of a human renal dipeptidase. The dipeptidase successfully synthesized the precursor of the dipeptide sweetener Z-l-Asp-d-AlaOBzl.

scholarly journals Complete Nucleotide Sequence of Plasmid pTN48, Encoding the CTX-M-14 Extended-Spectrum β-Lactamase from anEscherichia coliO102-ST405 Strain

2010 ◽  
Vol 55 (3) ◽  
pp. 1270-1273 ◽  
Author(s):  
Typhaine Billard-Pomares ◽  
Olivier Tenaillon ◽  
Hervé Le Nagard ◽  
Zoé Rouy ◽  
Stéphane Cruveiller ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Nucleotide Sequence ◽  
Complete Nucleotide Sequence ◽  
Phylogenetic Group ◽  
E Coli ◽  
Extended Spectrum ◽  
Group D ◽  
Replicon Type ◽  
M 14

ABSTRACTThe sequence of pTN48, a plasmid of the FII-FIB replicon type that encodes a CTX-M-14 enzyme in anEscherichia colistrain of the phylogenetic group D2O102-ST405 clone, was determined. pTN48 is, for the most part, a mosaic of virulence, antibiotic resistance, and addiction system modules found in various other plasmids. The presence of multiple addiction systems indicates that the plasmid should be stably maintained in theE. coliclone, favoring dissemination of the CTX-M-14 enzyme.

scholarly journals Gene Cluster for Assembly of Pilus Colonization Factor Antigen III of Enterotoxigenic Escherichia coli

2001 ◽  
Vol 69 (9) ◽  
pp. 5864-5873 ◽  
Author(s):  
Tooru Taniguchi ◽  
Yukihiro Akeda ◽  
Ayako Haba ◽  
Yoko Yasuda ◽  
Koichiro Yamamoto ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nucleotide Sequence ◽  
Gene Cluster ◽  
Enterotoxigenic Escherichia Coli ◽  
Human Colon Carcinoma Cell ◽  
E Coli ◽  
Colonization Factor ◽  
Type Iv ◽  
K 12 ◽  
Factor Antigen

ABSTRACT The assembly of pilus colonization factor antigen III (CFA/III) of enterotoxigenic Escherichia coli (ETEC) requires the processing of CFA/III major pilin (CofA) by a prepilin peptidase (CofP), similar to other type IV pilus formation systems. CofA is produced initially as a 26.5-kDa preform pilin (prepilin) and then processed to a 20.5-kDa mature pilin by CofP which is predicted to be localized in the inner membrane. In the present experiment, we determined the nucleotide sequence of the whole region for CFA/III formation and identified a cluster of 14 genes, includingcofA and cofP. Several proteins encoded bycof genes were similar to previously described proteins, such as the toxin-coregulated pili of Vibrio cholerae and the bundle-forming pili of enteropathogenic E. coli. The G+C content of the cof gene cluster was 37%, which was significantly lower than the average for the E. coli genome (50%). The introduction of a recombinant plasmid containing thecof gene cluster into the E. coli K-12 strain conferred CFA/III biogenesis and the ability of adhesion to the human colon carcinoma cell line Caco-2. This is the first report of a complete nucleotide sequence of the type IV pili found in human ETEC, and our results provide a useful model for studying the molecular mechanism of CFA/III biogenesis and the role of CFA/III in ETEC infection.

scholarly journals Growth of cell wall-defective variants of Escherichia coli: comparison of aerobic and anaerobic induction frequencies

1977 ◽  
Vol 6 (2) ◽  
pp. 166-171
Author(s):  
T W Huber ◽  
A W Brinkley
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
High Frequency ◽  
Anaerobic Incubation ◽  
Anaerobic Conditions ◽  
Group Iii ◽  
E Coli ◽  
Induction Frequency ◽  
Group I ◽  
Aerobic And Anaerobic

A method for quantitating the conversion of Escherichia coli to colony-forming, cell wall-defective (CWD) bacteria has been developed. The induction frequency, i.e., the percentage of the population recovered as CWD colonies was determined for 20 randomly selected clinical isolates of E. coli under aerobic and anaerobic incubation conditions. Penicillin (1,000 U/ML) was the inducing agent. The 20 strains segregated into three groups. Group I organisms produced CWD colonies with high frequency both aerobically and anaerobically. Grout II organisms showed a much higher induction frequency anaerobically than aerobically. Group III organisms were poor inducers. Thirty percent of the strains were group I, 50% were group II, and 20% were group III organisms. These data indicate that anaerobic conditions enhance the induction and growth of CWD E. coli in the research laboratory and suggest that anaerobic incubation may be important in recovery of medically significant CWD bacteria.

scholarly journals Molecular analysis of pathogenic Escherichia coli isolated from cow meat in Yogyakarta, Indonesia using 16S rRNA gene

2021 ◽  
Vol 22 (10) ◽  
Author(s):  
Alvita Indraswari ◽  
I Wayan Suardana ◽  
Aris Haryanto ◽  
Dyah Ayu Widiasih
Keyword(s):  
Escherichia Coli ◽  
Nucleotide Sequence ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Rrna Gene ◽  
Foodborne Disease ◽  
E Coli ◽  
Pathogenic Escherichia Coli ◽  
Cow Meat ◽  
Reference Strains

Abstract. Indraswari A, Suardana IW, Haryanto A, Widiasih DA. 2021. Molecular analysis of pathogenic Escherichia coli isolated from cow meat in Yogyakarta, Indonesia using 16S rRNA gene. Biodiversitas 22: 4566-4573. Meat has been recognized as a major source of foodborne disease and a public health problem. The characteristics of meat become an ideal growth medium for various microorganisms if not handled properly. Pathogenic Escherichia coli is one of the foodborne disease agents that causes diarrhea. Identification of pathogenic E. coli isolated from cow meat needs to be done. This research aims to study nucleotide sequence of 16S rRNA gene of pathogenic E. coli isolated from cow meat in Yogyakarta, Indonesia using Polymerase Chain Reaction (PCR). These fifteen isolates have been detected for eae target gene, then amplification of the 16S rRNA gene was carried out using primers 27F and 1492R. Phylogenetic tree reconstruction was performed on the fifteen isolates of pathogenic E. coli to figure out the relationship to reference strains available at the GenBank. Results show that nucleotide sequence among the fifteen isolates from different traditional markets in Yogyakarta, Indonesia and reference strains are very similar. The fifteen isolates have small genetic distance to the reference strains, and these fifteen isolates are also in the same clade with reference strains. This research shows that the fifteen isolates under investigation are closely related to the reference strains, which is Shiga-toxin producing E. coli (STEC). People should pay more attention in processing food stock, especially cow meat. Further research may focus on determining the strain of those fifteen isolates.

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