scholarly journals Role of Histone-Like Proteins H-NS and StpA in Expression of Virulence Determinants of Uropathogenic Escherichia coli

2006 ◽  
Vol 188 (15) ◽  
pp. 5428-5438 ◽  
Author(s):  
Claudia M. Müller ◽  
Ulrich Dobrindt ◽  
Gábor Nagy ◽  
Levente Emödy ◽  
Bernt Eric Uhlin ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Gene Expression Pattern ◽  
Direct Interaction ◽  
Virulence Determinants ◽  
Dna Arrays ◽  
Infectious Dose ◽  
E Coli ◽  
Huge Impact

ABSTRACT The histone-like protein H-NS is a global regulator in Escherichia coli that has been intensively studied in nonpathogenic strains. However, no comprehensive study on the role of H-NS and its paralogue, StpA, in gene expression in pathogenic E. coli has been carried out so far. Here, we monitored the global effects of H-NS and StpA in a uropathogenic E. coli isolate by using DNA arrays. Expression profiling revealed that more than 500 genes were affected by an hns mutation, whereas no effect of StpA alone was observed. An hns stpA double mutant showed a distinct gene expression pattern that differed in large part from that of the hns single mutant. This suggests a direct interaction between the two paralogues and the existence of distinct regulons of H-NS and an H-NS/StpA heteromeric complex. hns mutation resulted in increased expression of alpha-hemolysin, fimbriae, and iron uptake systems as well as genes involved in stress adaptation. Furthermore, several other putative virulence genes were found to be part of the H-NS regulon. Although the lack of H-NS, either alone or in combination with StpA, has a huge impact on gene expression in pathogenic E. coli strains, its effect on virulence is ambiguous. At a high infection dose, hns mutants trigger more sudden lethality due to their increased acute toxicity in murine urinary tract infection and sepsis models. At a lower infectious dose, however, mutants lacking H-NS are attenuated through their impaired growth rate, which can only partially be compensated for by the higher expression of numerous virulence factors.

scholarly journals Transcription of the Subtilase Cytotoxin Gene subAB1 in Shiga Toxin-Producing Escherichia coli Is Dependent on hfq and hns

2019 ◽  
Vol 85 (20) ◽  
Author(s):  
Laura Heinisch ◽  
Katharina Zoric ◽  
Maike Krause ◽  
Herbert Schmidt
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Shiga Toxin ◽  
Promoter Activity ◽  
Deletion Mutants ◽  
Content Type ◽  
E Coli ◽  
Intensive Investigation ◽  
Subtilase Cytotoxin

ABSTRACT Certain foodborne Shiga toxin-producing Escherichia coli (STEC) strains carry genes encoding the subtilase cytotoxin (SubAB). Although the mode of action of SubAB is under intensive investigation, information about the regulation of subAB gene expression is currently not available. In this study, we investigated the regulation of the chromosomal subAB1 gene in laboratory E. coli strain DH5α and STEC O113:H21 strain TS18/08 using a luciferase reporter gene assay. Special emphasis was given to the role of the global regulatory protein genes hfq and hns in subAB1 promoter activity. Subsequently, quantitative real-time PCR was performed to analyze the expression of Shiga toxin 2a (Stx2a), SubAB1, and cytolethal distending toxin V (Cdt-V) genes in STEC strain TS18/08 and its isogenic hfq and hns deletion mutants. The deletion of hfq led to a significant increase of up to 2-fold in subAB1 expression, especially in the late growth phase, in both strains. However, deletion of hns showed different effects on the promoter activity during the early and late exponential growth phases in both strains. Furthermore, upregulation of stx2a and cdt-V was demonstrated in hfq and hns deletion mutants in TS18/08. These data showed that the expression of subAB1, stx2a, and cdt-V is integrated in the regulatory network of global regulators Hfq and H-NS in Escherichia coli. IMPORTANCE Shiga toxin-producing Escherichia coli (STEC) strains are responsible for outbreaks of foodborne diseases, such as hemorrhagic colitis and the hemolytic uremic syndrome. The pathogenicity of those strains can be attributed to, among other factors, the production of toxins. Recently, the subtilase cytotoxin was detected in locus of enterocyte effacement (LEE)-negative STEC, and it was confirmed that it contributes to the cytotoxicity of those STEC strains. Although the mode of action of SubAB1 is under intensive investigation, the regulation of gene expression is currently not known. The global regulatory proteins H-NS and Hfq have impact on many cellular processes and have been described to regulate virulence factors as well. Here, we investigate the role of hns and hfq in expression of subAB1 as well as stx2a and cdt-V in an E. coli laboratory strain as well as in wild-type STEC strain TS18/08.

scholarly journals Interactions of the Hindgut Mucosa-Associated Microbiome with Its Host Regulate Shedding of Escherichia coli O157:H7 by Cattle

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Ou Wang ◽  
Tim A. McAllister ◽  
Graham Plastow ◽  
Kim Stanford ◽  
Brent Selinger ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Differentially Expressed Genes ◽  
Host Gene ◽  
Host Gene Expression ◽  
Differential Abundance ◽  
Content Type ◽  
E Coli ◽  
Differential Abundance Analysis

ABSTRACTCattle are the primary carrier ofEscherichia coliO157:H7, a foodborne human pathogen, and those shedding >104CFU/gram of feces ofE. coliO157:H7 are defined as supershedders (SS). This study investigated the rectoanal junction (RAJ) mucosa-associated microbiota and its relationship with host gene expression in SS and in cattle from whichE. coliO157:H7 was not detected (nonshedders [NS]), aiming to elucidate the mechanisms involved in supershedding. In total, 14 phyla, 66 families, and 101 genera of RAJ mucosa-associated bacteria were identified andFirmicutes(61.5 ± 7.5%),Bacteroidetes(27.9 ± 6.4%), andProteobacteria(5.5 ± 2.1%) were the predominant phyla. Differential abundance analysis of operational taxonomic units (OTUs) identified 2 OTUs unique to SS which were members ofBacteroidesandClostridiumand 7 OTUs unique to NS which were members ofCoprococcus,Prevotella,Clostridium, andPaludibacter. Differential abundance analysis of predicted microbial functions (using PICRUSt [phylogenetic investigation of communities by reconstruction of unobserved states]) revealed that 3 pathways had higher abundance (log2fold change, 0.10 to 0.23) whereas 12 pathways had lower abundance (log2fold change, −0.36 to −0.20) in SS. In addition, we identified significant correlations between expression of 19 differentially expressed genes and the relative abundance of predicted microbial functions, including nucleic acid polymerization and carbohydrate and amino acid metabolism. Our findings suggest that differences in RAJ microbiota at both the compositional and functional levels may be associated withE. coliO157:H7 supershedding and that certain microbial groups and microbial functions may influence RAJ physiology of SS by affecting host gene expression.IMPORTANCECattle with fecalE. coliO157:H7 at >104CFU per gram of feces have been defined as the supershedders, and they are responsible for the most of theE. coliO157:H7 spread into farm environment. Currently, no method is available for beef producers to eliminate shedding ofE. coliO157:H7 in cattle, and the lack of information about the mechanisms of supershedding greatly impedes the development of effective methods. This study investigated the role of the rectoanal junction (RAJ) mucosa-associated microbiome inE. coliO157:H7 shedding, and our results indicated that the compositions and functions of RAJ microbiota differed between supershedders and nonshedders. The identified relationship between the differentially abundant microbes and 19 previously identified differentially expressed genes suggests the role of host-microbial interactions involved inE. coliO157:H7 supershedding. Our findings provide a fundamental understanding of the supershedding phenomenon which is essential for the development of strategies, such as the use of directly fed microbials, to reduceE. coliO157:H7 shedding in cattle.

scholarly journals Coregulated assembly of actin-like FtsA polymers with FtsZ during Z-ring formation and division in Escherichia coli

2021 ◽  
Author(s):  
Josiah J. Morrison ◽  
Joseph Conti ◽  
Jodi L. Camberg
Keyword(s):  
Escherichia Coli ◽  
Atp Hydrolysis ◽  
Direct Interaction ◽  
Ring Formation ◽  
Phospholipid Vesicle ◽  
E Coli ◽  
C Terminus ◽  
Z Ring

AbstractIn Escherichia coli, the actin homolog FtsA localizes the cell division machinery, beginning with the Z-ring, to the cytoplasmic membrane through direct interaction with FtsZ. FtsZ polymers are first to assemble at the Z-ring at midcell, where they direct constriction and septation. While FtsZ polymerization is critical for establishing a functional Z-ring that leads to constriction, the assembly state of FtsA and the role of FtsA ATP utilization during division in E. coli remain unclear. Here, we show that ATP hydrolysis, FtsZ interaction, and phospholipid vesicle remodeling by FtsA are impaired by a substitution mutation at the predicted active site for hydrolysis. This mutation, Glu 14 to Arg, also impairs Z-ring assembly and division in vivo. To further investigate the role of phospholipid engagement and ATP utilization in regulating FtsA function, we characterized a truncated E. coli FtsA variant, FtsA(ΔMTS), which lacks the region at the C-terminus important for engaging the membrane and is defective for ATP hydrolysis. We show that E. coli FtsA(ΔMTS) forms ATP-dependent actin-like filaments and assembly is antagonized by FtsZ. Polymerization of FtsZ with GTP, or a non-hydrolyzable analog, blocks inhibition of ATP-dependent FtsA assembly, and instead favors coassembly of stable FtsA/FtsZ polymers. In the cell, FtsA/FtsZ coassembly is favored at midcell, where FtsZ polymerizes, and inhibited at regions where FtsZ polymers are destabilized by regulators, such as MinC at the poles or SlmA at the nucleoid. We show that MinC prevents recruitment of FtsZ, via FtsA, to phospholipids, suggesting that local interactions of MinC with FtsZ block membrane tethering and uncouple the Z-ring from its major membrane contact. During Z-ring formation, the coassembly of FtsZ polymers with FtsA is coordinated and is a critical early step in division. This step also serves as a checkpoint by responding to the suite of FtsZ assembly regulators in the cell that modulate Z-ring position and dynamics prior to initiating cell wall synthesis.

Functional analysis of sigma-70 consensus promoters in Pseudomonas aeruginosa and Escherichia coli

1997 ◽  
Vol 43 (10) ◽  
pp. 981-985 ◽  
Author(s):  
Bradley W. McLean ◽  
Shari L. Wiseman ◽  
Andrew M. Kropinski
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Pseudomonas Aeruginosa ◽  
Promoter Sequence ◽  
Broad Host Range ◽  
E Coli ◽  
Synthetic Promoters ◽  
Range Vector ◽  
Sigma 70

A series of synthetic promoters, based upon the Escherichia coli σ70 consensus promoter sequence, was constructed upstream of the lacZ reporter gene in the modified broad-host-range vector pQF52. The role of the intervening spacer region in gene expression in Pseudomonas aeruginosa and E. coli was studied by insertions and deletions within this region. In P. aeruginosa and E. coli the patterns of gene expression were identical with maximum β-galactosidase activity being measured from promoters possessing 19 bp in their intervening regions, presumably as a result of impeded promoter clearance with the consensus 17-bp promoter. In P. aeruginosa a second occurrence of enhanced activity, which could not be attributed to the involvement of the alternative sigma factor RpoN (σ54), was evident with the promoter having a 16-bp spacer.Key words: Pseudomonas aeruginosa, promoter, RpoD, RpoN, transcription.

scholarly journals Roles of the C-Terminal Amino Acids of Non-Hexameric Helicases: Insights from Escherichia coli UvrD

2021 ◽  
Vol 22 (3) ◽  
pp. 1018
Author(s):  
Hiroaki Yokota
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Single Molecule ◽  
Underlying Mechanism ◽  
Amino Acid Sequences ◽  
E Coli ◽  
X Ray Crystallography ◽  
Terminal Amino

Helicases are nucleic acid-unwinding enzymes that are involved in the maintenance of genome integrity. Several parts of the amino acid sequences of helicases are very similar, and these quite well-conserved amino acid sequences are termed “helicase motifs”. Previous studies by X-ray crystallography and single-molecule measurements have suggested a common underlying mechanism for their function. These studies indicate the role of the helicase motifs in unwinding nucleic acids. In contrast, the sequence and length of the C-terminal amino acids of helicases are highly variable. In this paper, I review past and recent studies that proposed helicase mechanisms and studies that investigated the roles of the C-terminal amino acids on helicase and dimerization activities, primarily on the non-hexermeric Escherichia coli (E. coli) UvrD helicase. Then, I center on my recent study of single-molecule direct visualization of a UvrD mutant lacking the C-terminal 40 amino acids (UvrDΔ40C) used in studies proposing the monomer helicase model. The study demonstrated that multiple UvrDΔ40C molecules jointly participated in DNA unwinding, presumably by forming an oligomer. Thus, the single-molecule observation addressed how the C-terminal amino acids affect the number of helicases bound to DNA, oligomerization, and unwinding activity, which can be applied to other helicases.

scholarly journals Distribution of Lactoferrin Is Related with Dynamics of Neutrophils in Bacterial Infected Mice Intestine

Molecules ◽  
2020 ◽  
Vol 25 (7) ◽  
pp. 1496 ◽  
Author(s):  
Li Liang ◽  
Zhen-Jie Wang ◽  
Guang Ye ◽  
Xue-You Tang ◽  
Yuan-Yuan Zhang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Antimicrobial Activity ◽  
Mucosal Immunity ◽  
Mrna Levels ◽  
Iron Binding ◽  
E Coli ◽  
New Knowledge ◽  
Activated Neutrophils ◽  
Binding Glycoprotein

Lactoferrin (Lf) is a conserved iron-binding glycoprotein with antimicrobial activity, which is present in secretions that recover mucosal sites regarded as portals of invaded pathogens. Although numerous studies have focused on exogenous Lf, little is known about its expression of endogenous Lf upon bacterial infection. In this study, we investigated the distribution of Lf in mice intestine during Escherichia coli (E. coli) K88 infection. PCR and immunohistology staining showed that mRNA levels of Lf significantly increased in duodenum, ileum and colon, but extremely decreased in jejunum at 8 h and 24 h after infection. Meanwhile, endogenous Lf was mostly located in the lamina propria of intestine villi, while Lf receptor (LfR) was in the crypts. It suggested that endogenous Lf-LfR interaction might not be implicated in the antibacterial process. In addition, it was interesting to find that the infiltration of neutrophils into intestine tissues was changed similarly to Lf expression. It indicated that the variations of Lf expression were rather due to an equilibrium between the recruitment of neutrophils and degranulation of activated neutrophils. Thus, this new knowledge will pave the way to a more effective understanding of the role of Lf in intestinal mucosal immunity.

Distinct gene expression patterns in chronic lymphocytic leukemia defined by usage of specific VH genes

Blood ◽  
2006 ◽  
Vol 107 (5) ◽  
pp. 2090-2093 ◽  
Author(s):  
Dirk Kienle ◽  
Axel Benner ◽  
Alexander Kröber ◽  
Dirk Winkler ◽  
Daniel Mertens ◽  
...  
Keyword(s):  
Gene Expression ◽  
Chronic Lymphocytic Leukemia ◽  
Expression Patterns ◽  
Gene Expression Pattern ◽  
Cell Receptor ◽  
Lymphocytic Leukemia ◽  
Expression Of Genes ◽  
Vh Genes ◽  
Signaling Activation

The mutation status and usage of specific VH genes such as V3-21 and V1-69 are potentially independent pathogenic and prognostic factors in chronic lymphocytic leukemia (CLL). To investigate the role of antigenic stimulation, we analyzed the expression of genes involved in B-cell receptor (BCR) signaling/activation, cell cycle, and apoptosis control in CLL using these specific VH genes compared to VH mutated (VH-MUT) and VH unmutated (VH-UM) CLL not using these VH genes. V3-21 cases showed characteristic expression differences compared to VH-MUT (up: ZAP70 [or ZAP-70]; down: CCND2, P27) and VH-UM (down: PI3K, CCND2, P27, CDK4, BAX) involving several BCR-related genes. Similarly, there was a marked difference between VH unmutated cases using the V1-69 gene and VH-UM (up: FOS; down: BLNK, SYK, CDK4, TP53). Therefore, usage of specific VH genes appears to have a strong influence on the gene expression pattern pointing to antigen recognition and ongoing BCR stimulation as a pathogenic factor in these CLL subgroups.

Prevalence and distribution of different diarrhoeagenicEscherichia colivirulotypes in major water bodies in Bangladesh

2013 ◽  
Vol 141 (12) ◽  
pp. 2516-2525 ◽  
Author(s):  
S. AKTER ◽  
M. ISLAM ◽  
K. S. AFREEN ◽  
N. AZMUDA ◽  
S. I. KHAN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Regional Distribution ◽  
Distribution Patterns ◽  
Aquatic Systems ◽  
Water Bodies ◽  
Virulence Determinants ◽  
Waterborne Pathogen ◽  
E Coli ◽  
Enriched Cultures ◽  
Natural Water Bodies

SUMMARYEscherichia coli, a prominent waterborne pathogen, causes a variety of gastrointestinal and extraintestinal infections that depend on virulence determinants. To monitor natural aquatic systems for virulence-associated genes ofE. coli, multiplex PCR was used in a survey covering 46 major natural water bodies in Bangladesh. DNA was extracted directly from water samples as well as from pre-enriched and enriched cultures during three successive seasons and assessed forE. colivirulotype distribution. From the five virulotypes, genes from the enterotoxigenic (ETEC), enteropathogenic (EPEC), and enterohaemorrhagic (EHEC) virulotypes were detected consistently, but genes from the enteroinvasive (EIEC) and enteroaggregative (EAEC) virulotypes were traced only occasionally. ETEC was the most prevalent virulotype, followed by EPEC. However, EIEC and EAEC virulotypes could not be detected in winter or the rainy season, respectively. Specific regional distribution patterns of differentE. colivirulotypes and their temporal fluctuations were identified. These observations may assist with assessing seasonal risk and identifying vulnerable areas of the country prone toE. coli-associated outbreaks.

scholarly journals Lessons from a large outbreak of Escherichia coli O157[ratio ]H7 infections: insights into the infectious dose and method of widespread contamination of hamburger patties

1999 ◽  
Vol 122 (2) ◽  
pp. 185-192 ◽  
Author(s):  
J. TUTTLE ◽  
T. GOMEZ ◽  
M. P. DOYLE ◽  
J. G. WELLS ◽  
T. ZHAO ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Ground Beef ◽  
Most Probable Number ◽  
Strong Argument ◽  
Probable Number ◽  
Infectious Dose ◽  
E Coli ◽  
Beef Patties ◽  
Large Outbreak ◽  
Microbiological Testing

Between November 1992 and February 1993, a large outbreak of Escherichia coli O157[ratio ]H7 infections occurred in the western USA and was associated with eating ground beef patties at restaurants of one fast-food chain. Restaurants that were epidemiologically linked with cases served patties produced on two consecutive dates; cultures of recalled ground beef patties produced on those dates yielded E. coli O157[ratio ]H7 strains indistinguishable from those isolated from patients, confirming the vehicle of illness. Seventy-six ground beef patty samples were cultured quantitatively for E. coli O157[ratio ]H7. The median most probable number of organisms was 1·5 per gram (range, <0·3–15) or 67·5 organisms per patty (range, <13·5–675). Correlation of the presence of E. coli O157[ratio ]H7 with other bacterial indicators yielded a significant association between coliform count and the presence of E. coli O157[ratio ]H7 (P=0·04). A meat traceback to investigate possible sources of contamination revealed cattle were probably initially colonized with E. coli O157[ratio ]H7, and that their slaughter caused surface contamination of meat, which once combined with meat from other sources, resulted in a large number of contaminated ground beef patties. Microbiological testing of meat from lots consumed by persons who became ill was suggestive of an infectious dose for E. coli O157[ratio ]H7 of fewer than 700 organisms. These findings present a strong argument for enforcing zero tolerance for this organism in processed food and for markedly decreasing contamination of raw ground beef. Process controls that incorporate microbiological testing of meat may assist these efforts.

SATP (YaaH), a succinate–acetate transporter protein in Escherichia coli

2013 ◽  
Vol 454 (3) ◽  
pp. 585-595 ◽  
Author(s):  
Joana Sá-Pessoa ◽  
Sandra Paiva ◽  
David Ribas ◽  
Inês Jesus Silva ◽  
Sandra Cristina Viegas ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Succinic Acid ◽  
Critical Role ◽  
Amino Acid Residues ◽  
E Coli ◽  
Transporter Protein ◽  
Affinity Constants ◽  
In Trans

In the present paper we describe a new carboxylic acid transporter in Escherichia coli encoded by the gene yaaH. In contrast to what had been described for other YaaH family members, the E. coli transporter is highly specific for acetic acid (a monocarboxylate) and for succinic acid (a dicarboxylate), with affinity constants at pH 6.0 of 1.24±0.13 mM for acetic acid and 1.18±0.10 mM for succinic acid. In glucose-grown cells the ΔyaaH mutant is compromised for the uptake of both labelled acetic and succinic acids. YaaH, together with ActP, described previously as an acetate transporter, affect the use of acetic acid as sole carbon and energy source. Both genes have to be deleted simultaneously to abolish acetate transport. The uptake of acetate and succinate was restored when yaaH was expressed in trans in ΔyaaH ΔactP cells. We also demonstrate the critical role of YaaH amino acid residues Leu131 and Ala164 on the enhanced ability to transport lactate. Owing to its functional role in acetate and succinate uptake we propose its assignment as SatP: the Succinate–Acetate Transporter Protein.

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