scholarly journals Induction and control of the autolytic system of Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 26-34
Author(s):  
M Leduc ◽  
R Kasra ◽  
J van Heijenoort
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Acid Synthesis ◽  
Induction Method ◽  
E Coli ◽  
Escherichia Coli Cells ◽  
Carbonyl Cyanide ◽  
And Control ◽  
First Time ◽  
Induced Autolysis

Various methods of inducing autolysis of Escherichia coli cells were investigated, some being described here for the first time. For the autolysis of growing cells only induction methods interfering with the biosynthesis of peptidoglycan were taken into consideration, whereas with harvested cells autolysis was induced by rapid osmotic or EDTA shock treatments. The highest rates of autolysis were observed after induction by moenomycin, EDTA, or cephaloridine. The different autolyses examined shared certain common properties. In particular, regardless of the induction method used, more or less extensive peptidoglycan degradation was observed, and 10(-2) M Mg2+ efficiently inhibited the autolytic process. However, for other properties a distinction was made between methods used for growing cells and those used for harvested cells. Autolysis of growing cells required RNA, protein, and fatty acid synthesis. No such requirements were observed with shock-induced autolysis performed with harvested cells. Thus, the effects of Mg2+, rifampicin, chloramphenicol, and cerulenin clearly suggest that distinct factors are involved in the control of the autolytic system of E. Coli. Uncoupling agents such as sodium azide, 2,4-dinitrophenol, and carbonyl-cyanide-m-chlorophenyl hydrazone used at their usual inhibiting concentration had no effect on the cephaloridine or shock-induced autolysis.

scholarly journals DEGR-factor Xa blocks disseminated intravascular coagulation initiated by Escherichia coli without preventing shock or organ damage

Blood ◽  
1991 ◽  
Vol 78 (2) ◽  
pp. 364-368 ◽  
Author(s):  
FB Jr Taylor ◽  
AC Chang ◽  
GT Peer ◽  
T Mather ◽  
K Blick ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Injury ◽  
Factor Xa ◽  
Organ Damage ◽  
Lethal Outcome ◽  
Chloromethyl Ketone ◽  
E Coli ◽  
And Control ◽  
First Time

One of the aims of research in the area of thrombosis has been to design an effective anticoagulant that would function in a predictable and direct manner. In evaluating the role of coagulation in sepsis we used factor Xa blocked in the active center with [5-(dimethylamino)1- naphthalenesulfonyl]-glutamylglycylarginyl+ ++ chloromethyl ketone (DEGR-Xa). We infused 1 mg/kg of DEGR-Xa together with LD100 concentrations of Escherichia coli (4 x 10(10) organisms/kg) into five baboons. As controls, we infused E coli alone into five baboons. The inflammatory, coagulant, and cell injury responses to E coli of both the treated and control groups were lethal and were similar in every respect except for the complete inhibition of the consumption of fibrinogen in the DEGR-Xa group. The half life of DEGR-Xa was approximately 10 hours and 2 hours, as determined by isotopic and enzyme-linked immunosorbent assays, respectively. These results for the first time demonstrate that, although coagulation occurs in E coli sepsis, fibrin formation per se did not influence the lethal outcome in this model. These results also show the effectiveness of DEGR-Xa as an anticoagulant and raise the possibility that it could serve as an alternative to anticoagulants currently in use.

scholarly journals DEGR-factor Xa blocks disseminated intravascular coagulation initiated by Escherichia coli without preventing shock or organ damage

Blood ◽  
1991 ◽  
Vol 78 (2) ◽  
pp. 364-368 ◽  
Author(s):  
FB Jr Taylor ◽  
AC Chang ◽  
GT Peer ◽  
T Mather ◽  
K Blick ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Injury ◽  
Factor Xa ◽  
Organ Damage ◽  
Lethal Outcome ◽  
Chloromethyl Ketone ◽  
E Coli ◽  
And Control ◽  
First Time

Abstract One of the aims of research in the area of thrombosis has been to design an effective anticoagulant that would function in a predictable and direct manner. In evaluating the role of coagulation in sepsis we used factor Xa blocked in the active center with [5-(dimethylamino)1- naphthalenesulfonyl]-glutamylglycylarginyl+ ++ chloromethyl ketone (DEGR-Xa). We infused 1 mg/kg of DEGR-Xa together with LD100 concentrations of Escherichia coli (4 x 10(10) organisms/kg) into five baboons. As controls, we infused E coli alone into five baboons. The inflammatory, coagulant, and cell injury responses to E coli of both the treated and control groups were lethal and were similar in every respect except for the complete inhibition of the consumption of fibrinogen in the DEGR-Xa group. The half life of DEGR-Xa was approximately 10 hours and 2 hours, as determined by isotopic and enzyme-linked immunosorbent assays, respectively. These results for the first time demonstrate that, although coagulation occurs in E coli sepsis, fibrin formation per se did not influence the lethal outcome in this model. These results also show the effectiveness of DEGR-Xa as an anticoagulant and raise the possibility that it could serve as an alternative to anticoagulants currently in use.

scholarly journals Fatty acid Composition and Antimicrobial Activity of Celtis australis L. Fruits

2010 ◽  
Vol 2 (2) ◽  
pp. 397-402 ◽  
Author(s):  
R. Badoni ◽  
D. K. Semwal ◽  
U. Rawat
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Fatty Acid ◽  
Methyl Oleate ◽  
Methyl Esters ◽  
Ethanolic Extract ◽  
Fatty Acid Analysis ◽  
E Coli ◽  
First Time ◽  
Celtis Australis

Methyl esters of fatty acid obtained from Celtis australis fruits were subjected to GC-MS in order to determine the identity and concentration of its constituents. Methyl oleate (25.7%), methyl palmitate (22.2%), methyl tricosanoate (13.3%), methyl lineolate (7.8%), methyl dotriacentanoate (2.6%) and methyl 14-acetylhydroxypalmitate (2.1%) were the major constituents out of total characterized composition (95.455%) of fatty acid. The ethanolic extract of fruits was used for evaluating its antimicrobial activity against Staphylococcus aureus, Pseudomonas auroginosa, Escherichia coli and Bacillus subtilis. The extract showed significant results against P. auroginosa and E. coli.  The antimicrobial activity and fatty acid analysis of C. australis of fatty acid fruits has been carried out for the first time. Keywords: Celtis australis; Ulmaceae; methyl oleate; methyl tricosanoate; Pseudomonas auroginosa; Escherichia coli. © 2010 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. DOI: 10.3329/jsr.v2i2.4056                J. Sci. Res. 2 (2), 397-402 (2010) 

scholarly journals Reassessment of the Genetic Regulation of Fatty Acid Synthesis in Escherichia coli: Global Positive Control by the Dual Functional Regulator FadR

2015 ◽  
Vol 197 (11) ◽  
pp. 1862-1872 ◽  
Author(s):  
L. My ◽  
N. Ghandour Achkar ◽  
J. P. Viala ◽  
E. Bouveret
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Fatty Acid Synthesis ◽  
Genetic Regulation ◽  
Transcriptional Regulator ◽  
Acid Synthesis ◽  
Biofuel Production ◽  
Global Regulator ◽  
Content Type ◽  
E Coli

ABSTRACTInEscherichia coli, the FadR transcriptional regulator represses the expression of fatty acid degradation (fad) genes. However, FadR is also an activator of the expression offabAandfabB, two genes involved in unsaturated fatty acid synthesis. Therefore, FadR plays an important role in maintaining the balance between saturated and unsaturated fatty acids in the membrane. We recently showed that FadR also activates the promoter upstream of thefabHgene (L. My, B. Rekoske, J. J. Lemke, J. P. Viala, R. L. Gourse, and E. Bouveret, J Bacteriol 195:3784–3795, 2013, doi:10.1128/JB.00384-13). Furthermore, recent transcriptomic and proteomic data suggested that FadR activates the majority of fatty acid (FA) synthesis genes. In the present study, we tested the role of FadR in the expression of all genes involved in FA synthesis. We found that FadR activates the transcription of all tested FA synthesis genes, and we identified the FadR binding site for each of these genes. This necessitated the reassessment of the transcription start sites foraccAandaccBgenes described previously, and we provide evidence for the presence of multiple promoters driving the expression of these genes. We showed further that regulation by FadR impacts the amount of FA synthesis enzymes in the cell. Our results show that FadR is a global regulator of FA metabolism inE. coli, acting both as a repressor of catabolism and an activator of anabolism, two directly opposing pathways.IMPORTANCEIn most bacteria, a transcriptional regulator tunes the level of FA synthesis enzymes. Oddly, such a global regulator still was missing forE. coli, which nonetheless is one of the prominent model bacteria used for engineering biofuel production using the FA synthesis pathway. Our work identifies the FadR functional dual regulator as a global activator of almost all FA synthesis genes inE. coli. Because FadR also is the repressor of FA degradation, FadR acts both as a repressor and an activator of the two opposite pathways of FA degradation and synthesis. Our results show that there are still discoveries waiting to be made in the understanding of the genetic regulation of FA synthesis, even in the very well-known bacteriumE. coli.

scholarly journals High prevalence of qnrA and qnrB genes among fluoroquinolone-resistant Escherichia coli isolates from a tertiary hospital in Southern Nigeria

2021 ◽  
Vol 45 (1) ◽  
Author(s):  
Chibuzor M. Nsofor ◽  
Mirabeau Y. Tattfeng ◽  
Chijioke A. Nsofor
Keyword(s):  
Escherichia Coli ◽  
Susceptibility Testing ◽  
Tertiary Hospital ◽  
Vaginal Swab ◽  
Fluoroquinolone Resistance ◽  
E Coli ◽  
Diffusion Technique ◽  
High Prevalence ◽  
Polymerase Chain ◽  
And Control

Abstract Background This study was aimed to determine the prevalence of qnr genes among fluoroquinolone-resistant Escherichia coli (FREC) isolates from Nigeria. Antimicrobial susceptibility testing was performed by disc diffusion technique. Polymerase chain reaction was used to identify Escherichia coli (E. coli) and for the detection of qnr genes. Results A total of 206 non-duplicate E. coli were isolated from 300 clinical specimens analyzed. In all, 30 (14.6%) of these isolates were FREC; the resistance to fluoroquinolones among these 30 FREC showed 80% (24), 86.7% (26), 86.7% (26), 100% (30), 86.7% (26), 93.3% (28) and 86.7% (26) were resistant to pefloxacin, ciprofloxacin, sparfloxacin, levofloxacin, nalidixic acid, ofloxacin and moxifloxacin, respectively. The distribution of FREC among the various sample sources analyzed showed that 14%, 10%, 13.3%, 16.7% and 20% of the isolates came from urine, stool, high vaginal swab, endo cervical swab and wound swab specimens, respectively. More FREC were isolated from female samples 73.3% (22) compared to male samples 26.7% (8) and were more prevalent among the age group 26–35 years (40%). Twenty eight out of the 30 (93.3%) FREC isolates possessed at least one fluoroquinolone resistance gene in the form of qnrA 10 (33.3%) and qnrB 18 (60%), respectively; qnrS was not detected among the FREC isolates analyzed and 13.5% of the isolates possessed both the qnrA and qnrB genes. Phylogenetic analysis showed that these isolates were genetically diverse. Conclusions These findings suggest a possible resistance to fluoroquinolone is of high interest for better management of patients and control of antimicrobial resistance in Nigeria.

Bacteriophages reduce Escherichia coli O157:H7 levels in experimentally inoculated sheep

2009 ◽  
Vol 89 (2) ◽  
pp. 285-293 ◽  
Author(s):  
S J Bach ◽  
R P Johnson ◽  
K. Stanford ◽  
T A McAllister
Keyword(s):  
Escherichia Coli ◽  
Oral Administration ◽  
Coliform Bacteria ◽  
Escherichia Coli O157 ◽  
Fecal Shedding ◽  
Total Coliforms ◽  
E Coli ◽  
Oral Inoculation ◽  
Experimental Treatments ◽  
And Control

Bacteriophage biocontrol has potential as a means of mitigating the prevalence of Escherichia coli O157:H7 in ruminants. The efficacy of oral administration of bacteriophages for reducing fecal shedding of E. coli O157:H7 by sheep was evaluated using 20 Canadian Arcott rams (50.0 ± 3.0) housed in four rooms (n = 5) in a contained facility. The rams had ad libitum access to drinking water and a pelleted barley-based total mixed ration, delivered once daily. Experimental treatments consisted of administration of E. coli O157:H7 (O157), E. coli O157:H7+bacteriophages (O157+phage), bacteriophages (phage), and control (CON). Oral inoculation of the rams with 109 CFU of a mixture of four nalidixic acid-resistant strains of E. coli O157:H7 was performed on day 0. A mixture of 1010 PFU of bacteriophages P5, P8 and P11 was administered on days -2, -1, 0, 6 and 7. Fecal samples collected on 14 occasions over 21 d were analyzed for E. coli O157:H7, total E. coli, total coliforms and bacteriophages. Sheep in treatment O157+phage shed fewer (P < 0.05) E. coli O157:H7 than did sheep in treatment O157. Populations of total coliforms and total E. coli were similar (P < 0.05) among treatments, implying that bacteriophage lysis of non-target E. coli and coliform bacteria in the gastrointestinal tract did not occur. Bacteriophage numbers declined rapidly over 21 d, which likely reduced the chance of collision between bacteria and bacteriophage. Oral administration of bacteriophages reduced shedding of E. coli O157:H7 by sheep, but a delivery system that would protect bacteriophages during passage through the intestine may increase the effectiveness of this strategy as well as allow phage to be administered in the feed.Key words: Escherichia coli O157:H7, bacteriophage, sheep, environment, coliforms

scholarly journals Identification and Characterization of a New Enoyl Coenzyme A Hydratase Involved in Biosynthesis of Medium-Chain-Length Polyhydroxyalkanoates in Recombinant Escherichia coli

2003 ◽  
Vol 185 (18) ◽  
pp. 5391-5397 ◽  
Author(s):  
Si Jae Park ◽  
Sang Yup Lee
Keyword(s):  
Escherichia Coli ◽  
Fatty Acid ◽  
Chain Length ◽  
Biosynthetic Pathway ◽  
Pha Synthase ◽  
Enzymatic Analysis ◽  
E Coli ◽  
Medium Chain ◽  
Medium Chain Length ◽  
Enoyl Coa Hydratase

ABSTRACT The biosynthetic pathway of medium-chain-length (MCL) polyhydroxyalkanoates (PHAs) from fatty acids has been established in fadB mutant Escherichia coli strain by expressing the MCL-PHA synthase gene. However, the enzymes that are responsible for the generation of (R)-3-hydroxyacyl coenzyme A (R3HA-CoAs), the substrates for PHA synthase, have not been thoroughly elucidated. Escherichia coli MaoC, which is homologous to Pseudomonas aeruginosa (R)-specific enoyl-CoA hydratase (PhaJ1), was identified and found to be important for PHA biosynthesis in a fadB mutant E. coli strain. When the MCL-PHA synthase gene was introduced, the fadB maoC double-mutant E. coli WB108, which is a derivative of E. coli W3110, accumulated 43% less amount of MCL-PHA from fatty acid compared with the fadB mutant E. coli WB101. The PHA biosynthetic capacity could be restored by plasmid-based expression of the maoCEc gene in E. coli WB108. Also, E. coli W3110 possessing fully functional β-oxidation pathway could produce MCL-PHA from fatty acid by the coexpression of the maoCEc gene and the MCL-PHA synthase gene. For the enzymatic analysis, MaoC fused with His6-Tag at its C-terminal was expressed in E. coli and purified. Enzymatic analysis of tagged MaoC showed that MaoC has enoyl-CoA hydratase activity toward crotonyl-CoA. These results suggest that MaoC is a new enoyl-CoA hydratase involved in supplying (R)-3-hydroxyacyl-CoA from the β-oxidation pathway to PHA biosynthetic pathway in the fadB mutant E. coli strain.

scholarly journals Regulation of Escherichia coli RelA Requires Oligomerization of the C-Terminal Domain

2001 ◽  
Vol 183 (2) ◽  
pp. 570-579 ◽  
Author(s):  
Michal Gropp ◽  
Yael Strausz ◽  
Miriam Gross ◽  
Gad Glaser
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Catalytic Domain ◽  
Mutational Analysis ◽  
Amino Acid Starvation ◽  
E Coli ◽  
Terminal Domain ◽  
Negative Effect ◽  
And Control ◽  
Two Hybrid

ABSTRACT The E. coli RelA protein is a ribosome-dependent (p)ppGpp synthetase that is activated in response to amino acid starvation. RelA can be dissected both functionally and physically into two domains: The N-terminal domain (NTD) (amino acids [aa] 1 to 455) contains the catalytic domain of RelA, and the C-terminal domain (CTD) (aa 455 to 744) is involved in regulating RelA activity. We used mutational analysis to localize sites important for RelA activity and control in these two domains. We inserted two separate mutations into the NTD, which resulted in mutated RelA proteins that were impaired in their ability to synthesize (p)ppGpp. When we caused the CTD inrelA + cells to be overexpressed, (p)ppGpp accumulation during amino acid starvation was negatively affected. Mutational analysis showed that Cys-612, Asp-637, and Cys-638, found in a conserved amino acid sequence (aa 612 to 638), are essential for this negative effect of the CTD. When mutations corresponding to these residues were inserted into the full-length relA gene, the mutated RelA proteins were impaired in their regulation. In attempting to clarify the mechanism through which the CTD regulates RelA activity, we found no evidence for competition for ribosomal binding between the normal RelA and the overexpressed CTD. Results from CyaA complementation experiments of the bacterial two-hybrid system fusion plasmids (G. Karimova, J. Pidoux, A. Ullmann, and D. Ladant, Proc. Natl. Acad. Sci. USA 95:5752–5756, 1998) indicated that the CTD (aa 564 to 744) is involved in RelA-RelA interactions. Our findings support a model in which RelA activation is regulated by its oligomerization state.

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