Imidazole Ring-Opened Purines: Occurence and Repair in Escherichia Coli and Mammalian Cells

Verocytotoxin (VT)-producing Escherichia coli (VTEC) are a newly recognized group of enteric pathogens which are increasingly being recognized as common causes of diarrhea in some geographic settings. Outbreak studies indicate that most patients with VTEC infection develop mild uncomplicated diarrhea. However, a significant risk of two serious and potentially life-threatening complications, hemorrhagic colitis and the hemolytic uremic syndrome, makes VTEC infection a public health problem of serious concern. The main reservoirs of VTEC appear to be the intestinal tracts of animals, and foods of animal (especially bovine) origin are probably the principal sources for human infection. The term VT refers to a family of subunit exotoxins with high biological activity. Individual VTEC strains elaborate one or both of at least two serologically distinct, bacteriophage-mediated VTs (VT1 and VT2) which are closely related to Shiga toxin and are thus also referred to as Shiga-like toxins. The holotoxins bind to cells, via their B subunits, to a specific receptor which is probably the glycolipid, globotriosyl ceramide (Gb3). Binding is followed by internalization of the A subunit, which, after it is proteolytically nicked and reduced to the A1 fragment, inhibits protein synthesis in mammalian cells by inactivating 60S ribosomal subunits through selective structural modification of 28S ribosomal ribonucleic acid. The mechanism of VTEC diarrhea is still controversial, and the relative roles of locally acting VT and "attaching and effacing adherence" of VTEC to the mucosa have yet to be resolved. There is increasing evidence that hemolytic uremic syndrome and possibly hemorrhagic colitis result from the systemic action of VT on vascular endothelial cells. The role of antitoxic immunity in preventing the systemic complications of VTEC infection is being explored. Antibiotics appear to be contraindicated in the treatment of VTEC infection. The most common VTEC serotype associated with human disease is O157:H7, but over 50 different VT-positive O:H serotypes have now been identified. The best strategies for diagnosing human VTEC infection include testing for the presence of free VT in fecal filtrates and examining fecal cultures for VTEC by means of deoxyribonucleic acid probes that specify genes encoding VT1 and VT2. Both methods are currently confined to specialized laboratories and await commercial development for wider use. In the meantime, most laboratories should continue to screen for the most common human VTEC serotype, O157:H7, using a sorbitol-containing MacConkey medium.

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Escherichia coli RecA protein modified with a nuclear location signal binds to chromosomes in living mammalian cells

Experimental Cell Research ◽

10.1016/0014-4827(92)90155-2 ◽

1992 ◽

Vol 198 (1) ◽

pp. 107-114 ◽

Cited By ~ 4

Author(s):

Mitsuru Kido ◽

Yoshihiro Yoneda ◽

Mahito Nakanishi ◽

Tsuyoshi Uchida ◽

Yoshio Okada

Keyword(s):

Escherichia Coli ◽

Mammalian Cells ◽

Reca Protein ◽

Nuclear Location Signal ◽

Nuclear Location

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Membrane-permeable luciferin esters for assay of firefly luciferase in live intact cells

Biochemical Journal ◽

10.1042/bj2760637 ◽

1991 ◽

Vol 276 (3) ◽

pp. 637-641 ◽

Cited By ~ 51

Author(s):

F F Craig ◽

A C Simmonds ◽

D Watmore ◽

F McCapra ◽

M R H White

Keyword(s):

Escherichia Coli ◽

Mammalian Cells ◽

Firefly Luciferase ◽

Luciferase Expression ◽

Intact Cells ◽

Cos Cells ◽

Escherichia Coli Cells ◽

Luminescent Signal ◽

The Difference ◽

Kinetics Of

Five esters of luciferin were synthesized and compared with native luciferin as substrates for firefly luciferase expressed in live intact mammalian cells. The esters themselves were not substrates for purified luciferase, but four were substrates for a purified esterase and all appeared to be hydrolysed to luciferin within mammalian cells. At a substrate concentration of 0.01 mM, the peak luminescence from the cos cells expressing luciferase was up to 6-fold greater with the esters than with unmodified luciferin. At 0.1 mM, the difference between luciferin and the esters was decreased. The kinetics of the luminescent signal with the different luciferin esters varied significantly, indicating possible differences in the rates of uptake, breakdown and enzyme inhibition. The esters did not support luminescence from Escherichia coli cells expressing firefly luciferase, suggesting a lack of appropriate esterase activity in this particular strain. The esters could be useful for the assay of luciferase expression in intact mammalian cells when luciferin levels are limiting, for example in tissues, and in plants. Alternative luciferin derivatives may allow further improvements in sensitivity.

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Escherichia coli and colorectal cancer: Unfolding the enigmatic relationship

Current Pharmaceutical Biotechnology ◽

10.2174/1389201022666210910094827 ◽

2021 ◽

Vol 22 ◽

Author(s):

Rogayeh Nouri ◽

Alka Hasani ◽

Kourosh Masnadi Shirazi ◽

Mohammad Reza Aliand ◽

Bita Sepehri ◽

...

Keyword(s):

Colorectal Cancer ◽

Escherichia Coli ◽

Mammalian Cells ◽

Chromosomal Rearrangements ◽

Current Evidence ◽

Dna Breaks ◽

Colon Cells ◽

E Coli ◽

Dna Mismatch ◽

Double Strand Dna Breaks

: Colorectal cancer (CRC) is one of the deadliest cancers in the world. Specific strains of intestinal Escherichia coli (E. coli) may influence the initiation and development of CRC by exploiting virulence factors and inflammatory pathways. Mucosa-associated E. coli strains are more prevalent in CRC biopsies in comparison to healthy controls. Moreover, these strains can survive and replicate within macrophages and induce a pro-inflammatory response. Chronic exposure to inflammatory mediators can lead to increased cell proliferation and cancer. Production of colobactin toxin by the majority of mucosa-associated E. coli isolated from CRC patients is another notable finding. Colibactin-producing E. coli strains, in particular, induce double-strand DNA breaks, stop the cell cycle, involve in chromosomal rearrangements of mammalian cells and are implicated in carcinogenic effects in animal models. Moreover, some enteropathogenic E. coli (EPEC) strains are able to survive and replicate in colon cells as chronic intracellular pathogens and may promote susceptibility to CRC by downregulation of DNA Mismatch Repair (MMR) proteins. In this review, we discuss current evidence and focus on the mechanisms by which E. coli can influence the development of CRC.

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Chemical Composition and Antibacterial and Cytotoxic Activities ofAllium hirtifoliumBoiss

BioMed Research International ◽

10.1155/2013/696835 ◽

2013 ◽

Vol 2013 ◽

pp. 1-8 ◽

Cited By ~ 19

Author(s):

Salmiah Ismail ◽

Farid Azizi Jalilian ◽

Amir Hossein Talebpour ◽

Mohsen Zargar ◽

Kamyar Shameli ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Chemical Composition ◽

Mammalian Cells ◽

Pathogenic Bacteria ◽

Cytotoxic Activities ◽

Hexadecenoic Acid ◽

Minimum Concentration ◽

Gram Positive Bacteria ◽

Microdilution Broth

Allium hirtifoliumBoiss. known as Persian shallot, is a spice used as a traditional medicine in Iran and, Mediterranean region. In this study, the chemical composition of the hydromethanolic extract of this plant was analyzed using GC/MS. The result showed that 9-hexadecenoic acid, 11,14-eicosadienoic acid, and n-hexadecanoic acid are the main constituents. The antibacterial activity of the shallot extract was also examined by disk diffusion and microdilution broth assays. It was demonstrated that Persian shallot hydromethanolic extract was effective against 10 different species of pathogenic bacteria including methicillin resistantStaphylococcus aureus(MRSA), methicillin sensitiveStaphylococcus aureus(MSSA),Staphylococcus aureus,Staphylococcus epidermidis,Streptococcus pneumoniae,Escherichia coli, Escherichia coliO157:H7,Salmonella typhimurium, Proteus mirabilis, andKlebsiella pneumoniae. Specifically, the minimum concentration of the extract which inhibited bacterial growth (MIC values) was 1.88 mg/mL for most of the gram-positive bacteria. This concentration was not much different from the concentration that was safe for mammalian cells (1.50 mg/mL) suggesting that the hydromethanolic extract of Persian shallot may be a safe and strong antibacterial agent.

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E1A 13S and 12S mRNA products made in Escherichia coli both function as nucleus-localized transcription activators but do not directly bind DNA.

Molecular and Cellular Biology ◽

10.1128/mcb.5.10.2653 ◽

1985 ◽

Vol 5 (10) ◽

pp. 2653-2661 ◽

Cited By ~ 77

Author(s):

B Ferguson ◽

B Krippl ◽

O Andrisani ◽

N Jones ◽

H Westphal ◽

...

Keyword(s):

Escherichia Coli ◽

Mammalian Cells ◽

Biochemical Properties ◽

Protein Product ◽

Gene Products ◽

E Coli ◽

Adenovirus E1a ◽

Myc Gene ◽

E1a Gene ◽

Transcription Activators

We previously purified and characterized functionally the Escherichia coli-expressed product of the human subgroup C adenovirus E1A 13S mRNA (B. Ferguson, N. Jones, J. Richter, and M. Rosenberg, Science 224:1343-1346, 1984; B. Krippl, B. Ferguson, M. Rosenberg, and H. Westphal, Proc. Natl. Acad. Sci. USA 81:6988-6992, 1984). We have now expressed in E. coli and purified the protein product encoded by the human subgroup C adenovirus E1A 12S mRNA and have compared the functional properties of this protein with those of the E1A 13S mRNA product. Using microinjection techniques to introduce these proteins into mammalian cells, we found that the E1A 12S mRNA product, like the 13S mRNA product, localized rapidly to the cell nucleus and induced adenovirus gene expression. Although both E1A gene products localized to the nucleus and stimulated adenovirus gene transcription, these proteins did not directly bind to DNA under conditions in which a known DNA-binding protein, the human c-myc gene product, bound DNA efficiently. Thus, the E1A and myc gene products, which have been related both structurally and functionally, exhibit distinctly different biochemical properties.

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Novel Roles for the AIDA Adhesin from Diarrheagenic Escherichia coli: Cell Aggregation and Biofilm Formation

Journal of Bacteriology ◽

10.1128/jb.186.23.8058-8065.2004 ◽

2004 ◽

Vol 186 (23) ◽

pp. 8058-8065 ◽

Cited By ~ 128

Author(s):

Orla Sherlock ◽

Mark A. Schembri ◽

Andreas Reisner ◽

Per Klemm

Keyword(s):

Escherichia Coli ◽

Biofilm Formation ◽

Mammalian Cells ◽

Gastrointestinal Disease ◽

Cell Aggregation ◽

Bacterial Attachment ◽

E Coli ◽

Abiotic Surfaces ◽

Broad Variety ◽

Self Association

ABSTRACT Diarrhea-causing Escherichia coli strains are responsible for numerous cases of gastrointestinal disease and constitute a serious health problem throughout the world. The ability to recognize and attach to host intestinal surfaces is an essential step in the pathogenesis of such strains. AIDA is a potent bacterial adhesin associated with some diarrheagenic E. coli strains. AIDA mediates bacterial attachment to a broad variety of human and other mammalian cells. It is a surface-displayed autotransporter protein and belongs to the selected group of bacterial glycoproteins; only the glycosylated form binds to mammalian cells. Here, we show that AIDA possesses self-association characteristics and can mediate autoaggregation of E. coli cells. We demonstrate that intercellular AIDA-AIDA interaction is responsible for bacterial autoaggregation. Interestingly, AIDA-expressing cells can interact with antigen 43 (Ag43)-expressing cells, which is indicative of an intercellular AIDA-Ag43 interaction. Additionally, AIDA expression dramatically enhances biofilm formation by E. coli on abiotic surfaces in flow chambers.

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