scholarly journals Mapping Stress-Induced Changes in Autoinducer AI-2 Production in Chemostat-Cultivated Escherichia coli K-12

2001 ◽  
Vol 183 (9) ◽  
pp. 2918-2928 ◽  
Author(s):  
Matthew P. DeLisa ◽  
James J. Valdes ◽  
William E. Bentley
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Quorum Sensing ◽  
Interleukin 2 ◽  
Heterologous Proteins ◽  
Induced Expression ◽  
E Coli ◽  
Chemostat Cultures ◽  
K 12

ABSTRACT Numerous gram-negative bacteria employ a cell-to-cell signaling mechanism, termed quorum sensing, for controlling gene expression in response to population density. Recently, this phenomenon has been discovered in Escherichia coli, and while pathogenicE. coli utilize quorum sensing to regulate pathogenesis (i.e., expression of virulence genes), the role of quorum sensing in nonpathogenic E. coli is less clear, and in particular, there is no information regarding the role of quorum sensing during the overexpression of recombinant proteins. The production of autoinducer AI-2, a signaling molecule employed by E. coli for intercellular communication, was studied in E. coli W3110 chemostat cultures using a Vibrio harveyi AI-2 reporter assay (M. G. Surrette and B. L. Bassler, Proc. Natl. Acad. Sci. USA 95:7046–7050, 1998). Chemostat cultures enabled a study of AI-2 regulation through steady-state and transient responses to a variety of environmental stimuli. Results demonstrated that AI-2 levels increased with the steady-state culture growth rate. In addition, AI-2 increased following pulsed addition of glucose, Fe(III), NaCl, and dithiothreitol and decreased following aerobiosis, amino acid starvation, and isopropyl-β-d-thiogalactopyranoside-induced expression of human interleukin-2 (hIL-2). In general, the AI-2 responses to several perturbations were indicative of a shift in metabolic activity or state of the cells induced by the individual stress. Because of our interest in the expression of heterologous proteins in E. coli, the transcription of four quorum-regulated genes and 20 stress genes was mapped during the transient response to induced expression of hIL-2. Significant regulatory overlap was revealed among several stress and starvation genes and known quorum-sensing genes.

scholarly journals Regulatory Role of PlaR (YiaJ) for Plant Utilization in Escherichia coli K-12

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Tomohiro Shimada ◽  
Yui Yokoyama ◽  
Takumi Anzai ◽  
Kaneyoshi Yamamoto ◽  
Akira Ishihama
Keyword(s):  
Escherichia Coli ◽  
Genetic System ◽  
Regulatory Role ◽  
E Coli ◽  
Warm Blooded Animal ◽  
Plant Utilization ◽  
K 12

AbstractOutside a warm-blooded animal host, the enterobacterium Escherichia coli K-12 is also able to grow and survive in stressful nature. The major organic substance in nature is plant, but the genetic system of E. coli how to utilize plant-derived materials as nutrients is poorly understood. Here we describe the set of regulatory targets for uncharacterized IclR-family transcription factor YiaJ on the E. coli genome, using gSELEX screening system. Among a total of 18 high-affinity binding targets of YiaJ, the major regulatory target was identified to be the yiaLMNOPQRS operon for utilization of ascorbate from fruits and galacturonate from plant pectin. The targets of YiaJ also include the genes involved in the utilization for other plant-derived materials as nutrients such as fructose, sorbitol, glycerol and fructoselysine. Detailed in vitro and in vivo analyses suggest that L-ascorbate and α-D-galacturonate are the effector ligands for regulation of YiaJ function. These findings altogether indicate that YiaJ plays a major regulatory role in expression of a set of the genes for the utilization of plant-derived materials as nutrients for survival. PlaR was also suggested to play protecting roles of E. coli under stressful environments in nature, including the formation of biofilm. We then propose renaming YiaJ to PlaR (regulator of plant utilization).

scholarly journals Quorum-Sensing Escherichia coli Regulator A: a Regulator of the LysR Family Involved in the Regulation of the Locus of Enterocyte Effacement Pathogenicity Island in Enterohemorrhagic E. coli

2002 ◽  
Vol 70 (6) ◽  
pp. 3085-3093 ◽  
Author(s):  
Vanessa Sperandio ◽  
Caiyi C. Li ◽  
James B. Kaper
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Type Iii Secretion ◽  
Pathogenicity Island ◽  
The Other ◽  
E Coli ◽  
Type Iii ◽  
Enterocyte Effacement ◽  
K 12 ◽  
Lysr Family

ABSTRACT The locus of enterocyte effacement (LEE) is a chromosomal pathogenicity island that encodes the proteins involved in the formation of the attaching and effacing lesions by enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic E. coli (EPEC). The LEE comprises 41 open reading frames organized in five major operons, LEE1, LEE2, LEE3, tir (LEE5), and LEE4, which encode a type III secretion system, the intimin adhesin, the translocated intimin receptor (Tir), and other effector proteins. The first gene of LEE1 encodes the Ler regulator, which activates all the other genes within the LEE. We previously reported that the LEE genes were activated by quorum sensing through Ler (V. Sperandio, J. L. Mellies, W. Nguyen, S. Shin, and J. B. Kaper, Proc. Natl. Acad. Sci. USA 96:15196-15201, 1999). In this study we report that a putative regulator in the E. coli genome is itself activated by quorum sensing. This regulator is encoded by open reading frame b3243; belongs to the LysR family of regulators; is present in EHEC, EPEC, and E. coli K-12; and shares homology with the AphB and PtxR regulators of Vibrio cholerae and Pseudomonas aeruginosa, respectively. We confirmed the activation of b3243 by quorum sensing by using transcriptional fusions and renamed this regulator quorum-sensing E. coli regulator A (QseA). We observed that QseA activated transcription of ler and therefore of the other LEE genes. An EHEC qseA mutant had a striking reduction of type III secretion activity, which was complemented when qseA was provided in trans. Similar results were also observed with a qseA mutant of EPEC. The QseA regulator is part of the regulatory cascade that regulates EHEC and EPEC virulence genes by quorum sensing.

scholarly journals Interaction between complement subcomponent C1q and bacterial lipopolysaccharides

1989 ◽  
Vol 257 (3) ◽  
pp. 865-873 ◽  
Author(s):  
A Zohair ◽  
S Chesne ◽  
R H Wade ◽  
M G Colomb
Keyword(s):  
Escherichia Coli ◽  
Chemical Modification ◽  
Essential Role ◽  
Wild Strain ◽  
E Coli ◽  
Diethyl Pyrocarbonate ◽  
Direct Binding ◽  
Bacterial Lipopolysaccharides ◽  
K 12

The heptose-less mutant of Escherichia coli, D31m4, bound complement subcomponent C1q and its collagen-like fragments (C1qCLF) with Ka values of 1.4 x 10(8) and 2.0 x 10(8) M-1 respectively. This binding was suppressed by chemical modification of C1q and C1qCLF using diethyl pyrocarbonate (DEPC). To investigate the role of lipopolysaccharides (LPS) in this binding, biosynthetically labelled [14C]LPS were purified from E. coli D31m4 and incorporated into liposomes prepared from phosphatidylcholine (PC) and phosphatidylethanolamine (PE) [PC/PE/LPS, 2:2:1, by wt.]. Binding of C1q or its collagen-like fragments to the liposomes was estimated via a flotation test. These liposomes bound C1q and C1qCLF with Ka values of 8.0 x 10(7) and 2.0 x 10(7) M-1; this binding was totally inhibited after chemical modification of C1q and C1qCLF by DEPC. Liposomes containing LPS purified from the wild-strain E. coli K-12 S also bound C1q and C1qCLF, whereas direct binding of C1q or C1qCLF to the bacteria was negligible. Diamines at concentrations which dissociate C1 into C1q and (C1r, C1s)2, strongly inhibited the interaction of C1q or C1qCLF with LPS. Removal of 3-deoxy-D-manno-octulosonic acid (2-keto-3-deoxyoctonic acid; KDO) from E. coli D31m4 LPS decreases the binding of C1qCLF to the bacteria by 65%. When this purified and modified LPS was incorporated into liposomes, the C1qCLF binding was completely abolished. These results show: (i) the essential role of the collagen-like moiety and probably its histidine residues in the interaction between C1q and the mutant D31m4; (ii) the contribution of LPS, particularly the anionic charges of KDO, to this interaction.

scholarly journals Cloning, Expression, and Characterization of Fimbrial Operon F9 from Enterohemorrhagic Escherichia coli O157:H7

2006 ◽  
Vol 74 (4) ◽  
pp. 2233-2244 ◽  
Author(s):  
Alison S. Low ◽  
Francis Dziva ◽  
Alfredo G. Torres ◽  
Jessenya L. Martinez ◽  
Tracy Rosser ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Epithelial Cells ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Enterohemorrhagic Escherichia Coli ◽  
Wild Type ◽  
Induced Expression ◽  
E Coli ◽  
Extracellular Matrix Components ◽  
K 12

ABSTRACT Recent transposon mutagenesis studies with two enterohemorrhagic Escherichia coli (EHEC) strains, a sero- type O26:H- strain and a serotype O157:H7 strain, led to identification of a putative fimbrial operon that promotes colonization of young calves (1 to 2 weeks old). The distribution of the gene encoding the major fimbrial subunit present in O-island 61 of EHEC O157:H7 in a characterized set of 78 diarrheagenic E. coli strains was determined, and this gene was found in 87.2% of the strains and is therefore not an EHEC-specific region. The cluster was amplified by long-range PCR and cloned into the inducible expression vector pBAD18. Induced expression in E. coli K-12 led to production of fimbriae, as demonstrated by transmission electron microscopy and sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The fimbriae were purified, and sera to the purified major subunit were raised and used to demonstrate expression from wild-type E. coli O157:H7 strains. Induced expression of the fimbriae, designated F9 fimbriae, was used to characterize binding to bovine epithelial cells, bovine gastrointestinal tissue explants, and extracellular matrix components. The fimbriae promoted increases in the levels of E. coli K-12 binding only to bovine epithelial cells. In contrast, induced expression of F9 fimbriae in E. coli O157:H7 significantly reduced adherence of the bacteria to bovine gastrointestinal explant tissue. This may have been due to physical hindrance of type III secretion-dependent attachment. The main F9 subunit gene was deleted in E. coli O157:H7, and the resulting mutant was compared with the wild-type strain for colonization in weaned cattle. While the shedding levels of the mutant were reduced, the animals were still colonized at the terminal rectum, indicating that the adhesin is not responsible for the rectal tropism observed but may contribute to colonization at other sites, as demonstrated previously with very young animals.

scholarly journals Role of CheB and CheR in the Complex Chemotactic and Aerotactic Pathway of Azospirillum brasilense

2006 ◽  
Vol 188 (13) ◽  
pp. 4759-4768 ◽  
Author(s):  
Bonnie B. Stephens ◽  
Star N. Loar ◽  
Gladys Alexandre
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Azospirillum Brasilense ◽  
Model Organism ◽  
Spatial Gradient ◽  
Wild Type ◽  
Temporal Gradient ◽  
E Coli ◽  
Significant Difference

ABSTRACT It has previously been reported that the alpha-proteobacterium Azospirillum brasilense undergoes methylation-independent chemotaxis; however, a recent study revealed cheB and cheR genes in this organism. We have constructed cheB, cheR, and cheBR mutants of A. brasilense and determined that the CheB and CheR proteins under study significantly influence chemotaxis and aerotaxis but are not essential for these behaviors to occur. First, we found that although cells lacking CheB, CheR, or both were no longer capable of responding to the addition of most chemoattractants in a temporal gradient assay, they did show a chemotactic response (albeit reduced) in a spatial gradient assay. Second, in comparison to the wild type, cheB and cheR mutants under steady-state conditions exhibited an altered swimming bias, whereas the cheBR mutant and the che operon mutant did not. Third, cheB and cheR mutants were null for aerotaxis, whereas the cheBR mutant showed reduced aerotaxis. In contrast to the swimming bias for the model organism Escherichia coli, the swimming bias in A. brasilense cells was dependent on the carbon source present and cells released methanol upon addition of some attractants and upon removal of other attractants. In comparison to the wild type, the cheB, cheR, and cheBR mutants showed various altered patterns of methanol release upon exposure to attractants. This study reveals a significant difference between the chemotaxis adaptation system of A. brasilense and that of the model organism E. coli and suggests that multiple chemotaxis systems are present and contribute to chemotaxis and aerotaxis in A. brasilense.

scholarly journals Role of Quorum Sensing and Antimicrobial Component Production by Serratia plymuthica in Formation of Biofilms, Including Mixed Biofilms with Escherichia coli

2006 ◽  
Vol 72 (11) ◽  
pp. 7294-7300 ◽  
Author(s):  
Pieter Moons ◽  
Rob Van Houdt ◽  
Abram Aertsen ◽  
Kristof Vanoirbeek ◽  
Yves Engelborghs ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Quorum Sensing ◽  
Biofilm Formation ◽  
Homoserine Lactone ◽  
Broth Culture ◽  
Confocal Laser ◽  
Wild Type ◽  
Serratia Plymuthica ◽  
E Coli

ABSTRACT We have previously characterized the N-acyl-l-homoserine lactone-based quorum-sensing system of the biofilm isolate Serratia plymuthica RVH1. Here we investigated the role of quorum sensing and of quorum-sensing-dependent production of an antimicrobial compound (AC) on biofilm formation by RVH1 and on the cocultivation of RVH1 and Escherichia coli in planktonic cultures or in biofilms. Biofilm formation of S. plymuthica was not affected by the knockout of splI or splR, the S. plymuthica homologs of the luxI or luxR quorum-sensing gene, respectively, or by the knockout of AC production. E. coli grew well in mixed broth culture with RVH1 until the latter reached 8.5 to 9.5 log CFU/ml, after which the E. coli colony counts steeply declined. In comparison, only a very small decline occurred in cocultures with the S. plymuthica AC-deficient and splI mutants. Complementation with exogenous N-hexanoyl-l-homoserine lactone rescued the wild-type phenotype of the splI mutant. The splR knockout mutant also induced a steep decline of E. coli, consistent with its proposed function as a repressor of quorum-sensing-regulated genes. The numbers of E. coli in 3-day-old mixed biofilms followed a similar pattern, being higher with S. plymuthica deficient in SplI or AC production than with wild-type S. plymuthica, the splR mutant, or the splI mutant in the presence of N-hexanoyl-l-homoserine lactone. Confocal laser scanning microscopic analysis of mixed biofilms established with strains producing different fluorescent proteins showed that E. coli microcolonies were less developed in the presence of RVH1 than in the presence of the AC-deficient mutant.

THE INFLUENCE OF THE PO1A1 MUTATION UPON RECOMBINATION IN ESCHERICHIA COLI K12

1979 ◽  
Vol 21 (3) ◽  
pp. 423-428 ◽  
Author(s):  
Barry W. Glickman ◽  
Tineke Rutgers
Keyword(s):  
Escherichia Coli ◽  
Dna Polymerase ◽  
Genetic Recombination ◽  
Dna Polymerase I ◽  
Multiple Gene ◽  
E Coli ◽  
Recombinational Process ◽  
K 12 ◽  
Polymerase I

Genetic recombination in Escherichia coli is a highly regulated process involving multiple gene products. We have investigated the role of DNA polymerase I in this process by studying the effect of the po1A1 mutation upon DNA transfer and conjugation in otherwise isogenic suppressor-free strains of E. coli K-12. It was found that the po1A1 mutation greatly reduces recombination in Hfr crosses (a factor of 20 in Po1+ × Po1A1 crosses and more than a factor of 100 in Po1A1 × Po1A1 crosses). However, since the po1A1 mutation reduces the strains capacity to act as a recipient for an F-prime and the analysis of recombination transfer gradients revealed no differences between Po1+ and Po1− strains, it is concluded that DNA polymerase I probably affects the transfer and/or stability of donor DNA rather than the recombinational process itself.

scholarly journals Conversion of Norepinephrine to 3,4-Dihdroxymandelic Acid in Escherichia coli Requires the QseBC Quorum-Sensing System and the FeaR Transcription Factor

2017 ◽  
Vol 200 (1) ◽  
Author(s):  
Sasikiran Pasupuleti ◽  
Nitesh Sule ◽  
Michael D. Manson ◽  
Arul Jayaraman
Keyword(s):  
Escherichia Coli ◽  
Transcription Factor ◽  
Quorum Sensing ◽  
Aromatic Amines ◽  
Response Regulator ◽  
Content Type ◽  
E Coli ◽  
Expression Of Genes ◽  
K 12 ◽  
Cognate Response Regulator

ABSTRACTThe detection of norepinephrine (NE) as a chemoattractant byEscherichia colistrain K-12 requires the combined action of the TynA monoamine oxidase and the FeaB aromatic aldehyde dehydrogenase. The role of these enzymes is to convert NE into 3,4-dihydroxymandelic acid (DHMA), which is a potent chemoattractant sensed by the Tsr chemoreceptor. These two enzymes must be induced by prior exposure to NE, and cells that are exposed to NE for the first time initially show minimal chemotaxis toward it. The induction of TynA and FeaB requires the QseC quorum-sensing histidine kinase, and the signaling cascade requires new protein synthesis. Here, we demonstrate that the cognate response regulator for QseC, the transcription factor QseB, is also required for induction. The related quorum-sensing kinase QseE appears not to be part of the signaling pathway, but its cognate response regulator, QseF, which is also a substrate for phosphotransfer from QseC, plays a nonessential role. The promoter of thefeaRgene, which encodes a transcription factor that has been shown to be essential for the expression oftynAandfeaB, has two predicted QseB-binding sites. One of these sites appears to be in an appropriate position to stimulate transcription from the P1promoter of thefeaRgene. This study unites two well-known pathways: one for expression of genes regulated by catecholamines (QseBC) and one for expression of genes required for metabolism of aromatic amines (FeaR, TynA, and FeaB). This cross talk allowsE. colito convert the host-derived and chemotactically inert NE into the potent bacterial chemoattractant DHMA.IMPORTANCEThe chemotaxis ofE. coliK-12 to norepinephrine (NE) requires the conversion of NE to 3,4-dihydroxymandleic acid (DHMA), and DHMA is both an attractant and inducer of virulence gene expression for a pathogenic enterohemorrhagicE. coli(EHEC) strain. The induction of virulence by DHMA and NE requires QseC. The results described here show that the cognate response regulator for QseC, QseB, is also required for conversion of NE into DHMA. Production of DHMA requires induction of a pathway involved in the metabolism of aromatic amines. Thus, the QseBC sensory system provides a direct link between virulence and chemotaxis, suggesting that chemotaxis to host signaling molecules may require that those molecules are first metabolized by bacterial enzymes to generate the actual chemoattractant.

Biosynthetic ornithine and arginine decarboxylases: correlation of rates of synthesis with activities in Escherichia coli during exponential growth and following nutritional shift-up

1982 ◽  
Vol 28 (8) ◽  
pp. 945-950
Author(s):  
Stephen M. Boyle ◽  
Kazuo Adachi
Keyword(s):  
Escherichia Coli ◽  
Steady State ◽  
Ornithine Decarboxylase ◽  
Biological Activities ◽  
Decarboxylase Activity ◽  
Biosynthetic Enzyme ◽  
Guanosine Tetraphosphate ◽  
E Coli ◽  
K 12

Whether guanosine tetraphosphate (ppGpp) has a role in the regulation of the putrescine biosynthetic enzyme, ornithine decarboxylase, in Escherichia coli is controversial. Different laboratories have reported either direct or indirect correlations between ppGpp levels and ornithine decarboxylase activity using different in vivo conditions. In this report, using conditions in vivo to modulate ppGpp levels, experiments are described which bear on the controversy. The rates of synthesis and biological activities of the biosynthetic ornithine and arginine decarboxylases (ODC and ADC) were measured in E. coli K-12 during experimental growth and during nutritional shift-up. There were good correlations between changes in their respective activities and the rates of synthesis of these enzymes during steady state or shift-up. ODC activity or rate of synthesis changed directly in concert with ppGpp levels, while ADC activity or rate of synthesis changed inversely with ppGpp levels. These observations support the contention that ppGpp does not inhibit ODC activity.

scholarly journals Altered Distribution of RNA Polymerase Lacking the Omega Subunit within the Prophages along the Escherichia coli K-12 Genome

mSystems ◽  
2018 ◽  
Vol 3 (1) ◽  
Author(s):  
Kaneyoshi Yamamoto ◽  
Yuki Yamanaka ◽  
Tomohiro Shimada ◽  
Paramita Sarkar ◽  
Myu Yoshida ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Rna Polymerase ◽  
Small Subunit ◽  
Open Reading Frames ◽  
Pcr Assay ◽  
E Coli ◽  
K 12 ◽  
Chip Chip ◽  
Reading Frames

The 91-amino-acid-residue small-subunit omega (the rpoZ gene product) of Escherichia coli RNA polymerase plays a structural role in the formation of RNA polymerase (RNAP) as a chaperone in folding the largest subunit (β′, of 1,407 residues in length), but except for binding of the stringent signal ppGpp, little is known of its role in the control of RNAP function. After analysis of genomewide distribution of wild-type and RpoZ-defective RNAP by the ChIP-chip method, we found alteration of the RpoZ-defective RNAP inside open reading frames, in particular, of the genes within prophages. For a set of the genes that exhibited altered occupancy of the RpoZ-defective RNAP, transcription was found to be altered as observed by qRT-PCR assay. All the observations here described indicate the involvement of RpoZ in recognition of some of the prophage genes. This study advances understanding of not only the regulatory role of omega subunit in the functions of RNAP but also the regulatory interplay between prophages and the host E. coli for adjustment of cellular physiology to a variety of environments in nature.

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