scholarly journals The mutagenic effect of Streptomycin on the nutritional requirement of E. coli (III)

1959 ◽  
Vol 14 (9) ◽  
pp. 732-737
Author(s):  
Naohiko TAMURA
Keyword(s):  
Mutagenic Effect ◽  
Nutritional Requirement ◽  
E Coli

scholarly journals Overexpression of the yeast HAM1 gene prevents 6-N-hydroxylaminopurine mutagenesis in Escherichia coli.

1998 ◽  
Vol 45 (3) ◽  
pp. 645-652 ◽  
Author(s):  
S G Kozmin ◽  
P Leroy ◽  
Y I Pavlov
Keyword(s):  
Escherichia Coli ◽  
Mutagenic Effect ◽  
Cellular Protein ◽  
Host Strain ◽  
Bacterial Cells ◽  
E Coli ◽  
Eukaryotic Organisms ◽  
Mutagenic Effects

The base analogue 6-N-hydroxylaminopurine (HAP) is a potent mutagen in a variety of prokaryotic and eukaryotic organisms. Mutations in the yeast ham1 gene render the cells hypersensitive to the mutagenic effect of HAP. We have found that this gene has homologues in a variety of organisms from bacteria to man. We have overexpressed yeast Ham1p in E. coli. We demonstrate that under conditions when this protein constitutes approximately 30% of cellular protein, the host strain is protected both from toxic and mutagenic effects of HAP. This result indicates that sole Ham1p activity might be sufficient for destruction of HAP or its metabolites in bacterial cells.

Metabolism of serine and glycine in E. coli K12. I. The role of formate in the metabolism of serine–glycine auxotrophs

1970 ◽  
Vol 16 (10) ◽  
pp. 933-940 ◽  
Author(s):  
Elaine B. Newman
Keyword(s):  
Sodium Formate ◽  
Intermediary Metabolism ◽  
Nutritional Requirement ◽  
E Coli ◽  
Serine Biosynthesis

Certain auxotrophs of E. coli K12 have a nutritional requirement for serine, glycine, or sodium formate. Formate is not a precursor of either serine or glycine; serine is a precursor of some but not all glycine. These findings do not fit in with the phosphorylated pathway of serine biosynthesis frequently postulated. A hypothesis is made that formate reactivates an otherwise nonfunctional enzyme of serine biosynthesis. This is only one of several possible hypotheses. Complications of intermediary metabolism of serine and glycine are considered in some detail. The conclusion is reached that this area of metabolism is less well understood than is frequently thought.

scholarly journals The antimutagenic effect of monoterpenes against UV-irradiation-, 4NQO- and t-BOOH-induced mutagenesis in coli

2011 ◽  
Vol 63 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Biljana Nikolic ◽  
Dragana Mitic-Culafic ◽  
Branka Vukovic-Gacic ◽  
Jelena Knezevic-Vukcevic
Keyword(s):  
Escherichia Coli ◽  
Dna Repair ◽  
Uv Irradiation ◽  
Mutagenic Effect ◽  
Evolutionary Conservation ◽  
Induced Mutations ◽  
Mutagenic Potential ◽  
E Coli ◽  
Antimutagenic Effect ◽  
Induced Mutagenesis

The aim of this work was to investigate the antimutagenic potential of monoterpenes from sage and basil in Escherichia coli. The mutagenic potential of monoterpenes was pre-screened with Salmonella/microsome reversion assay in strain TA100 and no mutagenic effect was detected. The antimutagenic potential against UV- 4NQO- and t-BOOH induced mutagenesis was evaluated in E. coli K12 and E. coli WP2 by reversion assays. The obtained results indicate that camphor and thujone reduce UV- and 4NQO-induced mutations; myrcene reduces t-BOOH-induced mutations, while eucalyptol and linalool reduce mutagenicity by all tested mutagens. Considering evolutionary conservation of DNA repair and antioxidative protection, the obtained results indicate that further antigenotoxicity studies should be undertaken in eukaryotes.

scholarly journals Physical and Functional Interactions between Escherichia coli MutY Glycosylase and Mismatch Repair Protein MutS

2006 ◽  
Vol 189 (3) ◽  
pp. 902-910 ◽  
Author(s):  
Haibo Bai ◽  
A-Lien Lu
Keyword(s):  
Escherichia Coli ◽  
Mismatch Repair ◽  
Base Excision Repair ◽  
Excision Repair ◽  
Mutagenic Effect ◽  
Binding Activity ◽  
E Coli ◽  
Repair Protein ◽  
Dna Strands ◽  
Base Excision

ABSTRACT Escherichia coli MutY and MutS increase replication fidelity by removing adenines that were misincorporated opposite 7,8-dihydro-8-oxo-deoxyguanines (8-oxoG), G, or C. MutY DNA glycosylase removes adenines from these mismatches through a short-patch base excision repair pathway and thus prevents G:C-to-T:A and A:T-to-G:C mutations. MutS binds to the mismatches and initiates the long-patch mismatch repair on daughter DNA strands. We have previously reported that the human MutY homolog (hMYH) physically and functionally interacts with the human MutS homolog, hMutSα (Y. Gu et al., J. Biol. Chem. 277:11135-11142, 2002). Here, we show that a similar relationship between MutY and MutS exists in E. coli. The interaction of MutY and MutS involves the Fe-S domain of MutY and the ATPase domain of MutS. MutS, in eightfold molar excess over MutY, can enhance the binding activity of MutY with an A/8-oxoG mismatch by eightfold. The MutY expression level and activity in mutS mutant strains are sixfold and twofold greater, respectively, than those for the wild-type cells. The frequency of A:T-to-G:C mutations is reduced by two- to threefold in a mutS mutY mutant compared to a mutS mutant. Our results suggest that MutY base excision repair and mismatch repair defend against the mutagenic effect of 8-oxoG lesions in a cooperative manner.

Endotoxin Alteration of the Mucopolysaccharide Blood Vessel Coating in Rats

1974 ◽  
Vol 32 ◽  
pp. 148-149
Author(s):  
D. E. Philpott ◽  
A. Takahashi
Keyword(s):  
Skeletal Muscle ◽  
Endothelial Cells ◽  
Salivary Gland ◽  
Carotid Artery ◽  
Basement Membrane ◽  
Coronary Vessels ◽  
Ruthenium Red ◽  
E Coli ◽  
Old Rats ◽  
The Brain

Two month, eight month and two year old rats were treated with 10 or 20 mg/kg of E. Coli endotoxin I. P. The eight month old rats proved most resistant to the endotoxin. During fixation the aorta, carotid artery, basil arartery of the brain, coronary vessels of the heart, inner surfaces of the heart chambers, heart and skeletal muscle, lung, liver, kidney, spleen, brain, retina, trachae, intestine, salivary gland, adrenal gland and gingiva were treated with ruthenium red or alcian blue to preserve the mucopolysaccharide (MPS) coating. Five, 8 and 24 hrs of endotoxin treatment produced increasingly marked capillary damage, disappearance of the MPS coating, edema, destruction of endothelial cells and damage to the basement membrane in the liver, kidney and lung.

Ribosome Structural Organization

1974 ◽  
Vol 32 ◽  
pp. 332-333
Author(s):  
James A. Lake
Keyword(s):  
Ribosomal Proteins ◽  
Structural Organization ◽  
Three Dimensional ◽  
Small Subunit ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Specific Antibodies ◽  
X Ray ◽  
E Coli ◽  
Complete Sequences

The understanding of ribosome structure has advanced considerably in the last several years. Biochemists have characterized the constituent proteins and rRNA's of ribosomes. Complete sequences have been determined for some ribosomal proteins and specific antibodies have been prepared against all E. coli small subunit proteins. In addition, a number of naturally occuring systems of three dimensional ribosome crystals which are suitable for structural studies have been observed in eukaryotes. Although the crystals are, in general, too small for X-ray diffraction, their size is ideal for electron microscopy.

Sites of Adsorption of the Bacteriophages T3 and T5 on the Wall of Escherichia Coli B.

1967 ◽  
Vol 25 ◽  
pp. 96-97
Author(s):  
Manfred E. Bayer
Keyword(s):  
Escherichia Coli ◽  
Cell Wall ◽  
Electron Microscope ◽  
Uranyl Acetate ◽  
E Coli ◽  
Receptor Sites ◽  
Rigid Cell Wall ◽  
Host Cell Surface ◽  
Bacterial Viruses ◽  
Escherichia Coli B

Bacterial viruses adsorb specifically to receptors on the host cell surface. Although the chemical composition of some of the cell wall receptors for bacteriophages of the T-series has been described and the number of receptor sites has been estimated to be 150 to 300 per E. coli cell, the localization of the sites on the bacterial wall has been unknown.When logarithmically growing cells of E. coli are transferred into a medium containing 20% sucrose, the cells plasmolize: the protoplast shrinks and becomes separated from the somewhat rigid cell wall. When these cells are fixed in 8% Formaldehyde, post-fixed in OsO4/uranyl acetate, embedded in Vestopal W, then cut in an ultramicrotome and observed with the electron microscope, the separation of protoplast and wall becomes clearly visible, (Fig. 1, 2). At a number of locations however, the protoplasmic membrane adheres to the wall even under the considerable pull of the shrinking protoplast. Thus numerous connecting bridges are maintained between protoplast and cell wall. Estimations of the total number of such wall/membrane associations yield a number of about 300 per cell.

Sign in / Sign up

Export Citation Format

Share Document