scholarly journals Pyridoxal Reductase, PdxI, Is Critical for Salvage of Pyridoxal in Escherichia coli

2020 ◽  
Vol 202 (12) ◽  
Author(s):  
Tomokazu Ito ◽  
Diana M. Downs
Keyword(s):  
Escherichia Coli ◽  
Reductase Activity ◽  
Active Form ◽  
Biologically Active ◽  
Vitamin B ◽  
Limited Information ◽  
Salvage Pathway ◽  
Content Type ◽  
E Coli ◽  
Wide Range

ABSTRACT Pyridoxal 5′-phosphate (PLP) is the biologically active form of vitamin B6 and an essential cofactor in all organisms. In Escherichia coli, PLP is synthesized via the deoxyxylulose 5-phosphate (DXP)-dependent pathway that includes seven enzymatic steps and generates pyridoxine 5′-phosphate as an intermediate. Additionally, E. coli is able to salvage pyridoxal, pyridoxine, and pyridoxamine B6 vitamers to produce PLP using kinases PdxK/PdxY and pyridox(am)ine phosphate oxidase (PdxH). We found that E. coli strains blocked in PLP synthesis prior to the formation of pyridoxine 5′-phosphate (PNP) required significantly less exogenous pyridoxal (PL) than strains lacking pdxH and identified the conversion of PL to pyridoxine (PN) during cultivation to be the cause. Our data showed that PdxI, shown to have PL reductase activity in vitro, was required for the efficient salvage of PL in E. coli. The pdxI+ E. coli strains converted exogenous PL to PN during growth, while pdxI mutants did not. In total, the data herein demonstrated that PdxI is a critical enzyme in the salvage of PL by E. coli. IMPORTANCE The biosynthetic pathway of pyridoxal 5′-phosphate (PLP) has extensively been studied in Escherichia coli, yet limited information is available about the vitamin B6 salvage pathway. We show that the protein PdxI (YdbC) is the primary pyridoxal (PL) reductase in E. coli and is involved in the salvage of PL. The orthologs of PdxI occur in a wide range of bacteria and plants, suggesting that PL reductase in the B6 salvage pathway is more widely distributed than previously expected.

scholarly journals Vibrio cholerae Triggers SOS and Mutagenesis in Response to a Wide Range of Antibiotics: a Route towards Multiresistance

2011 ◽  
Vol 55 (5) ◽  
pp. 2438-2441 ◽  
Author(s):  
Zeynep Baharoglu ◽  
Didier Mazel
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Vibrio Cholerae ◽  
Fluorescent Protein ◽  
Resistance Development ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Green Fluorescent ◽  
Regulated Promoters

ABSTRACTAntibiotic resistance development has been linked to the bacterial SOS stress response. InEscherichia coli, fluoroquinolones are known to induce SOS, whereas other antibiotics, such as aminoglycosides, tetracycline, and chloramphenicol, do not. Here we address whether various antibiotics induce SOS inVibrio cholerae. Reporter green fluorescent protein (GFP) fusions were used to measure the response of SOS-regulated promoters to subinhibitory concentrations of antibiotics. We show that unlike the situation withE. coli, all these antibiotics induce SOS inV. cholerae.

scholarly journals The Repeat-In-Toxin Family Member TosA Mediates Adherence of Uropathogenic Escherichia coli and Survival during Bacteremia

2011 ◽  
Vol 80 (2) ◽  
pp. 493-505 ◽  
Author(s):  
Patrick D. Vigil ◽  
Travis J. Wiles ◽  
Michael D. Engstrom ◽  
Lev Prasov ◽  
Matthew A. Mulvey ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Virulence Factors ◽  
Upper Urinary Tract ◽  
Host Cells ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Novel Target ◽  
Tract Infections

ABSTRACTUropathogenicEscherichia coli(UPEC) is responsible for the majority of uncomplicated urinary tract infections (UTI) and represents the most common bacterial infection in adults. UPEC utilizes a wide range of virulence factors to colonize the host, including the novel repeat-in-toxin (RTX) protein TosA, which is specifically expressed in the host urinary tract and contributes significantly to the virulence and survival of UPEC.tosA, found in strains within the B2 phylogenetic subgroup ofE. coli, serves as a marker for strains that also contain a large number of well-characterized UPEC virulence factors. The presence oftosAin anE. coliisolate predicts successful colonization of the murine model of ascending UTI, regardless of the source of the isolate. Here, a detailed analysis of the function oftosArevealed that this gene is transcriptionally linked to genes encoding a conserved type 1 secretion system similar to other RTX family members. TosA localized to the cell surface and was found to mediate (i) adherence to host cells derived from the upper urinary tract and (ii) survival in disseminated infections and (iii) to enhance lethality during sepsis (as assessed in two different animal models of infection). An experimental vaccine, using purified TosA, protected vaccinated animals against urosepsis. From this work, it was concluded that TosA belongs to a novel group of RTX proteins that mediate adherence and host damage during UTI and urosepsis and could be a novel target for the development of therapeutics to treat ascending UTIs.

scholarly journals Bioinformatic and Molecular Analysis of Inverse Autotransporters from Escherichia coli

mSphere ◽  
2019 ◽  
Vol 4 (4) ◽  
Author(s):  
Kelvin G. K. Goh ◽  
Danilo G. Moriel ◽  
Steven J. Hancock ◽  
Minh-Duy Phan ◽  
Mark A. Schembri
Keyword(s):  
Escherichia Coli ◽  
Cell Surface ◽  
Biofilm Formation ◽  
Secretion System ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Type V Secretion ◽  
K 12 ◽  
Type V

ABSTRACT Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCE Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.

scholarly journals Proteorhodopsin Overproduction Enhances the Long-Term Viability of Escherichia coli

2019 ◽  
Vol 86 (1) ◽  
Author(s):  
Yizhi Song ◽  
Michaël L. Cartron ◽  
Philip J. Jackson ◽  
Paul A. Davison ◽  
Mark J. Dickman ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Raman Spectroscopy ◽  
Cell Membrane ◽  
Single Cell ◽  
Marine Bacteria ◽  
Membrane Area ◽  
Content Type ◽  
E Coli ◽  
Wide Range

ABSTRACT Genes encoding the photoreactive protein proteorhodopsin (PR) have been found in a wide range of marine bacterial species, reflecting the significant contribution that PR makes to energy flux and carbon cycling in ocean ecosystems. PR can also confer advantages to enhance the ability of marine bacteria to survive periods of starvation. Here, we investigate the effect of heterologously produced PR on the viability of Escherichia coli. Quantitative mass spectrometry shows that E. coli, exogenously supplied with the retinal cofactor, assembles as many as 187,000 holo-PR molecules per cell, accounting for approximately 47% of the membrane area; even cells with no retinal synthesize ∼148,000 apo-PR molecules per cell. We show that populations of E. coli cells containing PR exhibit significantly extended viability over many weeks, and we use single-cell Raman spectroscopy (SCRS) to detect holo-PR in 9-month-old cells. SCRS shows that such cells, even incubated in the dark and therefore with inactive PR, maintain cellular levels of DNA and RNA and avoid deterioration of the cytoplasmic membrane, a likely basis for extended viability. The substantial proportion of the E. coli membrane required to accommodate high levels of PR likely fosters extensive intermolecular contacts, suggested to physically stabilize the cell membrane and impart a long-term benefit manifested as extended viability in the dark. We propose that marine bacteria could benefit similarly from a high PR content, with a stabilized cell membrane extending survival when those bacteria experience periods of severe nutrient or light limitation in the oceans. IMPORTANCE Proteorhodopsin (PR) is part of a diverse, abundant, and widespread superfamily of photoreactive proteins, the microbial rhodopsins. PR, a light-driven proton pump, enhances the ability of the marine bacterium Vibrio strain AND4 to survive and recover from periods of starvation, and heterologously produced PR extends the viability of nutrient-limited Shewanella oneidensis. We show that heterologously produced PR enhances the viability of E. coli cultures over long periods of several weeks and use single-cell Raman spectroscopy (SCRS) to detect PR in 9-month-old cells. We identify a densely packed and consequently stabilized cell membrane as the likely basis for extended viability. Similar considerations are suggested to apply to marine bacteria, for which high PR levels represent a significant investment in scarce metabolic resources. PR-stabilized cell membranes in marine bacteria are proposed to keep a population viable during extended periods of light or nutrient limitation, until conditions improve.

scholarly journals A Toxic Environment: a Growing Understanding of How Microbial Communities Affect Escherichia coli O157:H7 Shiga Toxin Expression

2020 ◽  
Vol 86 (24) ◽  
Author(s):  
Erin M. Nawrocki ◽  
Hillary M. Mosso ◽  
Edward G. Dudley
Keyword(s):  
Escherichia Coli ◽  
Shiga Toxin ◽  
Microbial Interactions ◽  
Severe Illness ◽  
Content Type ◽  
E Coli ◽  
Wide Range ◽  
Lambdoid Prophage

ABSTRACT Enterohemorrhagic Escherichia coli (EHEC) strains, including E. coli O157:H7, cause severe illness in humans due to the production of Shiga toxin (Stx) and other virulence factors. Because Stx is coregulated with lambdoid prophage induction, its expression is especially susceptible to environmental cues. Infections with Stx-producing E. coli can be difficult to model due to the wide range of disease outcomes: some infections are relatively mild, while others have serious complications. Probiotic organisms, members of the gut microbiome, and organic acids can depress Stx production, in many cases by inhibiting the growth of EHEC strains. On the other hand, the factors currently known to amplify Stx act via their effect on the stx-converting phage. Here, we characterize two interactive mechanisms that increase Stx production by O157:H7 strains: first, direct interactions with phage-susceptible E. coli, and second, indirect amplification by secreted factors. Infection of susceptible strains by the stx-converting phage can expand the Stx-producing population in a human or animal host, and phage infection has been shown to modulate virulence in vitro and in vivo. Acellular factors, particularly colicins and microcins, can kill O157:H7 cells but may also trigger Stx expression in the process. Colicins, microcins, and other bacteriocins have diverse cellular targets, and many such molecules remain uncharacterized. The identification of additional Stx-amplifying microbial interactions will improve our understanding of E. coli O157:H7 infections and help elucidate the intricate regulation of pathogenicity in EHEC strains.

scholarly journals Additional Og-Typing PCR Techniques Targeting Escherichia coli-Novel and Shigella-Unique O-Antigen Biosynthesis Gene Clusters

2020 ◽  
Vol 58 (11) ◽  
Author(s):  
Atsushi Iguchi ◽  
Hironobu Nishii ◽  
Kazuko Seto ◽  
Jiro Mitobe ◽  
Kenichi Lee ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Strong Association ◽  
Gene Clusters ◽  
Epidemiological Studies ◽  
Content Type ◽  
E Coli ◽  
O Antigen ◽  
Wide Range ◽  
Biosynthesis Gene ◽  
Almost All

ABSTRACT The O-serogrouping of pathogenic Escherichia coli is a standard method for subtyping strains for epidemiological studies and controls. O-serogroup diversification shows a strong association with the genetic diversity in some O-antigen biosynthesis gene clusters. Through genomic studies, in addition to the types of O-antigen biosynthesis gene clusters (Og-types) from conventional O-serogroup strains, a number of novel Og-types have been found in E. coli isolates. To assist outbreak investigations and surveillance of pathogenic E. coli at inspection institutes, in previous studies, we developed PCR methods that could determine almost all conventional O-serogroups and some novel Og-types. However, there are still many Og-types that may not be determined by simple genetic methods such as PCR. Thus, in the present study, we aimed to develop an additional Og-typing PCR system. Based on the novel Og-types, including OgN32, OgN33, and OgN34, presented in this study, we designed an additional 24 PCR primer pairs targeting 14 novel and 2 diversified E. coli Og-types and 8 Shigella-unique Og-types. Subsequently, we developed 5 new multiplex PCR sets consisting of 33 primers, including the aforementioned 24 primers and 9 primers reported in previous studies. The accuracy and specificity of the PCR system was validated using approximately 260 E. coli and Shigella O-serogroup and Og-type reference strains. The Og-typing PCR system reported here can determine a wide range of Og-types of E. coli and may help epidemiological studies, in addition to the surveillance of pathogenic E. coli.

scholarly journals The Ribosomal S10 Protein Is a General Target for Decreased Tigecycline Susceptibility

2015 ◽  
Vol 59 (9) ◽  
pp. 5561-5566 ◽  
Author(s):  
Kathryn Beabout ◽  
Troy G. Hammerstrom ◽  
Anisha Maria Perez ◽  
Bárbara Freitas Magalhães ◽  
Amy G. Prater ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Experimental Evolution ◽  
Binding Pocket ◽  
Gram Positive ◽  
Content Type ◽  
E Coli ◽  
Species Cluster ◽  
Wide Range ◽  
Translational Inhibitor

ABSTRACTTigecycline is a translational inhibitor with efficacy against a wide range of pathogens. Using experimental evolution, we adaptedAcinetobacter baumannii,Enterococcus faecium,Escherichia coli, andStaphylococcus aureusto growth in elevated tigecycline concentrations. At the end of adaptation, 35 out of 47 replicate populations had clones with a mutation inrpsJ, the gene that encodes the ribosomal S10 protein. To validate the role of mutations inrpsJin conferring tigecycline resistance, we showed that mutation ofrpsJalone inEnterococcus faecaliswas sufficient to increase the tigecycline MIC to the clinical breakpoint of 0.5 μg/ml. Importantly, we also report the first identification ofrpsJmutations associated with decreased tigecycline susceptibility inA. baumannii,E. coli, andS. aureus. The identified S10 mutations across both Gram-positive and -negative species cluster in the vertex of an extended loop that is located near the tigecycline-binding pocket within the 16S rRNA. These data indicate that S10 is a general target of tigecycline adaptation and a relevant marker for detecting reduced susceptibility in both Gram-positive and -negative pathogens.

scholarly journals Lipopolysaccharide core type diversity in the Escherichia coli species in association with phylogeny, virulence gene repertoire and distribution of type VI secretion systems

2021 ◽  
Vol 7 (9) ◽  
Author(s):  
Sébastien O. Leclercq ◽  
Maxime Branger ◽  
David G. E. Smith ◽  
Pierre Germon
Keyword(s):  
Escherichia Coli ◽  
Type Species ◽  
Virulence Gene ◽  
Uneven Distribution ◽  
Gene Repertoire ◽  
Content Type ◽  
E Coli ◽  
Link Type ◽  
Wide Range ◽  
K 12

Escherichia coli is a very versatile species for which diversity has been explored from various perspectives highlighting, for example, phylogenetic groupings and pathovars, as well as a wide range of O serotypes. The highly variable O-antigen, the most external part of the lipopolysaccharide (LPS) component of the outer membrane of E. coli , is linked to the innermost lipid A through the core region of LPS of which five different structures, denominated K-12, R1, R2, R3 and R4, have been characterized so far. The aim of the present study was to analyse the prevalence of these LPS core types in the E. coli species and explore their distribution in the different E. coli phylogenetic groups and in relationship with the virulence gene repertoire. Results indicated an uneven distribution of core types between the different phylogroups, with phylogroup A strains being the most diverse in terms of LPS core types, while phylogroups B1, D and E strains were dominated by the R3 type, and phylogroups B2 and C strains were dominated by the R1 type. Strains carrying the LEE virulence operon were mostly of the R3 type whatever the phylogroup while, within phylogroup B2, strains carrying a K-12 core all belonged to the complex STc131, one of the major clones of extraintestinal pathogenic E. coli (ExPEC) strains. The origin of this uneven distribution is discussed but remains to be fully explained, as well as the consequences of carrying a specific core type on the wider aspects of bacterial phenotype.

scholarly journals Activity Spectrum of Colicins Produced by Shigella sonnei and Genetic Mechanism of Colicin Resistance in Conspecific S. sonnei Strains and Escherichia coli

2014 ◽  
Vol 59 (1) ◽  
pp. 152-158 ◽  
Author(s):  
Fatema Calcuttawala ◽  
Chellaram Hariharan ◽  
Gururaja P. Pazhani ◽  
Santanu Ghosh ◽  
Thandavarayan Ramamurthy
Keyword(s):  
Escherichia Coli ◽  
Shigella Sonnei ◽  
Genetic Mechanism ◽  
Vitamin B ◽  
Content Type ◽  
E Coli ◽  
Fluctuation Test ◽  
Uptake Assay ◽  
Activity Spectrum

ABSTRACTColicin-mediated killing is an example of allelopathy, which has been found among several bacteria. Screening of 42 strains ofShigella sonneiisolated from diarrheal patients revealed that 39 (93%)S. sonneistrains were positive for colicin production againstEscherichia coliDH5α. In the PCR-based detection of the colicin types, 36 (92.3%) were identified as E3, 2 (5.1%) as E3 and E8, and 1 (2.6%) as E3 and E2. RepresentativeS. sonneistrains producing heterologous colicins exhibited antagonism against diarrheagenicEscherichia coli(DEC) groups. Although it is known that mutation in the colicin receptor renders the host resistant to colicin, there is a dearth of information on the genetic characterization of such mutants. In the fluctuation test, colicin-resistantE. colimutants were found to occur spontaneously at the rates of 2.51 × 10−8and 5.52 × 10−8per generation when exposed to colicins E3 and E8 and colicins E3 and E2, respectively. Genotypic characterization of colicin-resistantE. coli(ECCr) andS. sonnei(SSCr) strains displayed mutations in thebtuBgene, which encodes the receptor for vitamin B12uptake. This gene was interrupted by various insertion sequences, such as IS1, IS2, and IS911. Complementation of ECCrand SSCrwith plasmid-bornebtuB(pbtuB) accomplished restoration of the colicin-susceptible phenotype. The vitamin B12uptake assay gave an insight into the physiological relevance of thebtuBmutation. Our studies provide insights into the latent influence ofS. sonneicolicins in governing the existence of some of the shigellae and all of the DEC and the genetic mechanism underlying the emergence of resistance.

scholarly journals Virulence of Escherichia coli Clinical Isolates in a Murine Sepsis Model in Relation to Sequence Type ST131 Status, Fluoroquinolone Resistance, and Virulence Genotype

2012 ◽  
Vol 80 (4) ◽  
pp. 1554-1562 ◽  
Author(s):  
James R. Johnson ◽  
Stephen B. Porter ◽  
George Zhanel ◽  
Michael A. Kuskowski ◽  
Erick Denamur
Keyword(s):  
Escherichia Coli ◽  
Study Groups ◽  
Sequence Type ◽  
Clinical Isolates ◽  
Fluoroquinolone Resistance ◽  
Content Type ◽  
E Coli ◽  
Sepsis Model ◽  
Virulence Potential ◽  
Wide Range

ABSTRACTEscherichia colisequence type ST131 (O25b:H4) has emerged over the past decade as a globally disseminated, multidrug-resistant pathogen. Unlike traditional antimicrobial-resistantE. coli, ST131 derives from virulence-associated phylogenetic group B2 and exhibits extraintestinal virulence factors. This, plus preliminary evidence of virulence in experimental animals, has suggested that ST131's epidemic emergence may be due to high virulence potential, compared with otherE. colitypes. To test this hypothesis, we compared a large number of matched ST131 and non-ST131E. coliclinical isolates, both fluoroquinolone resistant and susceptible, plus isolates from classic extraintestinal pathogenicE. coli(ExPEC) sequence types (STs) and case report ST131 household transmission isolates, for virulence in a mouse subcutaneous sepsis model. Overall, in mice, the study isolates produced a wide range of lethality and clinical illness. However, neither ST131 status nor fluoroquinolone phenotype correlated with this diversity of illness severity, which occurred within each of the 6 study groups. In contrast, multiple known or suspected ExPEC virulence genes, includingpap(P fimbriae),vat(vacuolating toxin),kpsMII (group 2 capsule),ibeA(invasion of brain endothelium), andclbB/N(colibactin synthesis), plus molecularly defined ExPEC status, were significantly associated with virulence. These findings point away from ST131 isolates as having higher virulence potential compared with otherE. colitypes in causing invasive extraintestinal infections and suggest instead that ST131's epidemiological success may reflect enhanced fitness for upstream steps in pathogenesis or in colonization and transmission. Additionally, the extensive within-ST virulence diversity suggests an opportunity to compare closely related strains to identify the responsible genetic determinants.

Sign in / Sign up

Export Citation Format

Share Document