A novel peroxiredoxin of the plant Sedum lineare is a homologue of Escherichia coli bacterioferritin co-migratory protein (Bcp)

We cloned a gene encoding a 17-kDa protein from a cDNA library of the plant Sedum lineare and found that its deduced amino acid sequence showed similarities to those of Escherichia coli bacterioferritin co-migratory protein (Bcp) and its homologues, which comprise a discrete group associated with the peroxiredoxin (Prx) family. Studies of the recombinant 17-kDa protein produced in E. coli cells revealed that it actually had a thioredoxin-dependent peroxidase activity, the hallmark of the Prx family. PrxQ, as we now designate the 17-kDa protein, had two cysteine residues (Cys-44 and Cys-49) well conserved among proteins of the Bcp group. These two cysteines were demonstrated to be essential for the thioredoxin-dependent peroxidase activity by analysis of mutant proteins, suggesting that these residues are involved in the formation of an intramolecular disulphide bond as an intermediate in the reaction cycle. Expression of PrxQ suppressed the hypersensitivity of an E. coli bcp mutant to peroxides, indicating that it might exert an antioxidant activity in vivo. The sequence data presented have been deposited in the GenBank/EMBL/DDBJ nucleotide sequence databases under the accession number AB037598.

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Genetic and Functional Analyses of the Conserved C-Terminal Core Domain of Escherichia coli FtsZ

Journal of Bacteriology ◽

10.1128/jb.181.24.7531-7544.1999 ◽

1999 ◽

Vol 181 (24) ◽

pp. 7531-7544 ◽

Cited By ~ 175

Author(s):

Xiaolan Ma ◽

William Margolin

Keyword(s):

Escherichia Coli ◽

Amino Acid ◽

Immunoblot Analysis ◽

Conserved Residues ◽

Core Domain ◽

Mutant Proteins ◽

E Coli ◽

Stable Mutant ◽

Functional Analyses

ABSTRACT In Escherichia coli, FtsZ is required for the recruitment of the essential cell division proteins FtsA and ZipA to the septal ring. Several C-terminal deletions of E. coliFtsZ, including one of only 12 amino acids that removes the highly conserved C-terminal core domain, failed to complement chromosomalftsZ mutants when expressed on a plasmid. To identify key individual residues within the core domain, six highly conserved residues were replaced with alanines. All but one of these mutants (D373A) failed to complement an ftsZ chromosomal mutant. Immunoblot analysis demonstrated that whereas I374A and F377A proteins were unstable in the cell, L372A, D373A, P375A, and L378A proteins were synthesized at normal levels, suggesting that they were specifically defective in some aspect of FtsZ function. In addition, all four of the stable mutant proteins were able to localize and form rings at potential division sites in chromosomal ftsZ mutants, implying a defect in a function other than localization and multimerization. Because another proposed function of FtsZ is the recruitment of FtsA and ZipA, we tested whether the C-terminal core domain was important for interactions with these proteins. Using two different in vivo assays, we found that the 12-amino-acid truncation of FtsZ was defective in binding to FtsA. Furthermore, two point mutants in this region (L372A and P375A) showed weakened binding to FtsA. In contrast, ZipA was capable of binding to all four stable point mutants in the FtsZ C-terminal core but not to the 12-amino-acid deletion.

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Dual Repression by Fe2+-Fur and Mn2+-MntR of the mntH Gene, Encoding an NRAMP-Like Mn2+ Transporter in Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.183.16.4806-4813.2001 ◽

2001 ◽

Vol 183 (16) ◽

pp. 4806-4813 ◽

Cited By ~ 104

Author(s):

Silke I. Patzer ◽

Klaus Hantke

Keyword(s):

Escherichia Coli ◽

Consensus Sequence ◽

Transcriptional Regulator ◽

Binding Region ◽

Gene Encoding ◽

Lower Affinity ◽

E Coli ◽

Metal Transporter ◽

Dnase I Footprinting

ABSTRACT The uptake of Mn2+, a cofactor for several enzymes inEscherichia coli, is mediated by MntH, a proton-dependent metal transporter, which also recognizes Fe2+ with lower affinity. MntH belongs to the NRAMP family of eukaryotic Fe2+ and Mn2+ transporters. In E. coli strains with chromosomal mntH-lacZ fusions,mntH was partially repressed by both Mn2+ and Fe2+. Inactivation of fur resulted in the loss of Fe2+-dependent repression of mntHtranscription, demonstrating that Fe2+ repression depends on the global iron regulator Fur. However, these furmutants still showed Mn2+-dependent repression ofmntH. The Mn2+-responsive transcriptional regulator of mntH was identified as the gene product ofo155 (renamed MntR). mntR mutants were impaired in Mn2+ but not Fe2+ repression ofmntH transcription. Binding of purified MntR to themntH operator was manganese dependent. The binding region was localized by DNase I footprinting analysis and covers a nearly perfect palindrome. The Fur binding site, localized within 22 nucleotides of the mntH operator by in vivo operator titration assays, resembles the Fur-box consensus sequence.

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In Vivo Transduction with Shiga Toxin 1-Encoding Phage

Infection and Immunity ◽

10.1128/iai.66.9.4496-4498.1998 ◽

1998 ◽

Vol 66 (9) ◽

pp. 4496-4498 ◽

Cited By ~ 107

Author(s):

David W. K. Acheson ◽

Joachim Reidl ◽

Xiaoping Zhang ◽

Gerald T. Keusch ◽

John J. Mekalanos ◽

...

Keyword(s):

Escherichia Coli ◽

Gastrointestinal Tract ◽

Shiga Toxin ◽

Recipient Strain ◽

Gene Encoding ◽

E Coli ◽

A Subunit

ABSTRACT To facilitate the study of intestinal transmission of the Shiga toxin 1 (Stx1)-converting phage H-19B, Tn10d-blamutagenesis of an Escherichia coli H-19B lysogen was undertaken. Two mutants containing insertions in the gene encoding the A subunit of Stx1 were isolated. The resultant ampicillin-resistantE. coli strains lysogenic for these phages produced infectious H-19B particles but not active toxin. These lysogens were capable of transducing an E. coli recipient strain in the murine gastrointestinal tract, thereby demonstrating that lysogens of Shiga toxin-converting phages give rise to infectious virions within the host gastrointestinal tract.

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Growth Phase and Growth Rate Regulation of therapA Gene, Encoding the RNA Polymerase-Associated Protein RapA in Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.183.20.6126-6134.2001 ◽

2001 ◽

Vol 183 (20) ◽

pp. 6126-6134 ◽

Cited By ~ 14

Author(s):

Julio E. Cabrera ◽

Ding Jun Jin

Keyword(s):

Escherichia Coli ◽

Growth Rate ◽

Rna Polymerase ◽

Growth Phase ◽

Gene Encoding ◽

Rate Regulation ◽

E Coli ◽

Growth Rate Control

ABSTRACT The Escherichia coli rapA gene encodes the RNA polymerase (RNAP)-associated protein RapA, which is a bacterial member of the SWI/SNF helicase-like protein family. We have studied therapA promoter and its regulation in vivo and determined the interaction between RNAP and the promoter in vitro. We have found that the expression of rapA is growth phase dependent, peaking at the early log phase. The growth phase control ofrapA is determined at least by one particular feature of the promoter: it uses CTP as the transcription-initiating nucleotide instead of a purine, which is used for most E. colipromoters. We also found that the rapA promoter is subject to growth rate regulation in vivo and that it forms intrinsic unstable initiation complexes with RNAP in vitro. Furthermore, we have shown that a GC-rich or discriminator sequence between the −10 and +1 positions of the rapA promoter is responsible for its growth rate control and the instability of its initiation complexes with RNAP.

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Characterization and in Vivo Cloning of prlC, a Suppressor of Signal Sequence Mutations in Escherichia coli K12

Genetics ◽

10.1093/genetics/116.4.513 ◽

1987 ◽

Vol 116 (4) ◽

pp. 513-521

Author(s):

Nancy J Trun ◽

Thomas J Silhavy

Keyword(s):

Escherichia Coli ◽

Genetic Mapping ◽

Signal Sequence ◽

Illegitimate Recombination ◽

Mutant Phenotype ◽

E Coli ◽

Physical Location ◽

Sequence Deletion ◽

New Alleles

ABSTRACT The prlC gene of E. coli was originally identified as an allele, prlC1, which suppresses certain signal sequence mutations in the genes for several exported proteins. We have isolated six new alleles of prlC that also confer this phenotype. These mutations can be placed into three classes based on the degree to which they suppress the lamBsignal sequence deletion, lamBs78. Genetic mapping reveals that the physical location of the mutations in prlC correlates with the strength of the suppression, suggesting that different regions of the gene can be altered to yield a suppressor phenotype. We also describe an in vivo cloning procedure using λplacMu9H. The procedure relies on transposition and illegitimate recombination to generate a specialized transducing phage that carries prlC1. This method should be applicable to any gene for which there is a mutant phenotype.

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Molecular surveillance of shiga toxigenic Escherichia coli in selected beef abattoirs in Osun State Nigeria

Scientific Reports ◽

10.1038/s41598-021-93347-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Femi Ayoade ◽

Judith Oguzie ◽

Philomena Eromon ◽

Omolola E. Omotosho ◽

Tosin Ogunbiyi ◽

...

Keyword(s):

Escherichia Coli ◽

Sequence Analysis ◽

Block Design ◽

Latex Agglutination ◽

Pcr Analysis ◽

Accession Number ◽

E Coli ◽

Representative Isolate ◽

Randomized Block Design ◽

Toxigenic Strains

AbstractShiga toxigenic strains of E. coli (STEC) known to be etiological agents for diarrhea were screened for their incidence/occurrence in selected abattoirs sources in Osogbo metropolis of Osun State, Nigeria using a randomized block design. Samples were plated directly on selective and differential media and E. coli isolates. Multiplex PCR analysis was used to screen for the presence of specific virulence factors. These were confirmed serologically as non-O157 STEC using latex agglutination serotyping kit. Sequence analysis of PCR products was performed on a representative isolate showing the highest combination of virulence genes using the 16S gene for identification purposes only. Results showed that the average cfu/cm2 was significantly lower in the samples collected at Sekona-2 slaughter slab compared with those collected at Al-maleek batch abattoir and Sekona-1 slaughter slab in ascending order at P = 0.03. Moreover, the average cfu/cm2E. coli in samples collected from butchering knife was significantly lower when compared with that of the workers’ hand (P = 0.047) and slaughtering floor (P = 0.047) but not with the slaughter table (P = 0.98) and effluent water from the abattoir house (P = 0.39). These data suggest that the abattoir type may not be as important in the prevalence and spread of STEC as the hygiene practices of the workers. Sequence analysis of a representative isolate showed 100% coverage and 96.46% percentage identity with Escherichia coli O113:H21 (GenBank Accession number: CP031892.1) strain from Canada. This sequence was subsequently submitted to GenBank with accession number MW463885. From evolutionary analyses, the strain from Nigeria, sequenced in this study, is evolutionarily distant when compared with the publicly available sequences from Nigeria. Although no case of E. coli O157 was found within the study area, percent occurrence of non-O157 STEC as high as 46.3% at some of the sampled sites is worrisome and requires regulatory interventions in ensuring hygienic practices at the abattoirs within the study area.

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Mechanistic insights into synergy between nalidixic acid and tetracycline against clinical isolates of Acinetobacter baumannii and Escherichia coli

Communications Biology ◽

10.1038/s42003-021-02074-5 ◽

2021 ◽

Vol 4 (1) ◽

Author(s):

Amit Gaurav ◽

Varsha Gupta ◽

Sandeep K. Shrivastava ◽

Ranjana Pathania

Keyword(s):

Escherichia Coli ◽

Acinetobacter Baumannii ◽

Nalidixic Acid ◽

Bacterial Infections ◽

Clinical Isolates ◽

Hospital Environment ◽

Infection Model ◽

Drug Resistant ◽

E Coli

AbstractThe increasing prevalence of antimicrobial resistance has become a global health problem. Acinetobacter baumannii is an important nosocomial pathogen due to its capacity to persist in the hospital environment. It has a high mortality rate and few treatment options. Antibiotic combinations can help to fight multi-drug resistant (MDR) bacterial infections, but they are rarely used in the clinics and mostly unexplored. The interaction between bacteriostatic and bactericidal antibiotics are mostly reported as antagonism based on the results obtained in the susceptible model laboratory strain Escherichia coli. However, in the present study, we report a synergistic interaction between nalidixic acid and tetracycline against clinical multi-drug resistant A. baumannii and E. coli. Here we provide mechanistic insight into this dichotomy. The synergistic combination was studied by checkerboard assay and time-kill curve analysis. We also elucidate the mechanism behind this synergy using several techniques such as fluorescence spectroscopy, flow cytometry, fluorescence microscopy, morphometric analysis, and real-time polymerase chain reaction. Nalidixic acid and tetracycline combination displayed synergy against most of the MDR clinical isolates of A. baumannii and E. coli but not against susceptible isolates. Finally, we demonstrate that this combination is also effective in vivo in an A. baumannii/Caenorhabditis elegans infection model (p < 0.001)

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Lysyl-tRNA synthetase from Escherichia coli K12. Chromatographic heterogeneity and the lysU-gene product

Biochemical Journal ◽

10.1042/bj2480043 ◽

1987 ◽

Vol 248 (1) ◽

pp. 43-51 ◽

Cited By ~ 17

Author(s):

J Charlier ◽

R Sanchez

Keyword(s):

Escherichia Coli ◽

Gene Product ◽

Activity Ratio ◽

Deae Cellulose ◽

Trna Synthetase ◽

Trna Synthetases ◽

E Coli ◽

Aminoacyl Trna Synthetases

In contrast with most aminoacyl-tRNA synthetases, the lysyl-tRNA synthetase of Escherichia coli is coded for by two genes, the normal lysS gene and the inducible lysU gene. During its purification from E. coli K12, lysyl-tRNA synthetase was monitored by its aminoacylation and adenosine(5′)tetraphospho(5′)adenosine (Ap4A) synthesis activities. Ap4A synthesis was measured by a new assay using DEAE-cellulose filters. The heterogeneity of lysyl-tRNA synthetase (LysRS) was revealed on hydroxyapatite; we focused on the first peak, LysRS1, because of its higher Ap4A/lysyl-tRNA activity ratio at that stage. Additional differences between LysRS1 and LysRS2 (major peak on hydroxyapatite) were collected. LysRS1 was eluted from phosphocellulose in the presence of the substrates, whereas LysRS2 was not. Phosphocellulose chromatography was used to show the increase of LysRS1 in cells submitted to heat shock. Also, the Mg2+ optimum in the Ap4A-synthesis reaction is much higher for LysRS1. LysRS1 showed a higher thermostability, which was specifically enhanced by Zn2+. These results in vivo and in vitro strongly suggest that LysRS1 is the heat-inducible lysU-gene product.

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degS Is Necessary for Virulence and Is among Extraintestinal Escherichia coli Genes Induced in Murine Peritonitis

Infection and Immunity ◽

10.1128/iai.71.6.3088-3096.2003 ◽

2003 ◽

Vol 71 (6) ◽

pp. 3088-3096 ◽

Cited By ~ 40

Author(s):

Peter Redford ◽

Paula L. Roesch ◽

Rodney A. Welch

Keyword(s):

Escherichia Coli ◽

Urinary Tract Infection ◽

Urinary Tract ◽

Tract Infection ◽

Luria Bertani ◽

Broth Culture ◽

Wild Type ◽

E Coli ◽

Virulence Attenuation

ABSTRACT Extraintestinal Escherichia coli strains cause meningitis, sepsis, urinary tract infection, and other infections outside the bowel. We examined here extraintestinal E. coli strain CFT073 by differential fluorescence induction. Pools of CFT073 clones carrying a CFT073 genomic fragment library in a promoterless gfp vector were inoculated intraperitoneally into mice; bacteria were recovered by lavage 6 h later and then subjected to fluorescence-activated cell sorting. Eleven promoters were found to be active in the mouse but not in Luria-Bertani (LB) broth culture. Three are linked to genes for enterobactin, aerobactin, and yersiniabactin. Three others are linked to the metabolic genes metA, gltB, and sucA, and another was linked to iha, a possible adhesin. Three lie before open reading frames of unknown function. One promoter is associated with degS, an inner membrane protease. Mutants of the in vivo-induced loci were tested in competition with the wild type in mouse peritonitis. Of the mutants tested, only CFT073 degS was found to be attenuated in peritoneal and in urinary tract infection, with virulence restored by complementation. CFT073 degS shows growth similar to that of the wild type at 37°C but is impaired at 43°C or in 3% ethanol LB broth at 37°C. Compared to the wild type, the mutant shows similar serum survival, motility, hemolysis, erythrocyte agglutination, and tolerance to oxidative stress. It also has the same lipopolysaccharide appearance on a silver-stained gel. The basis for the virulence attenuation is unclear, but because DegS is needed for σE activity, our findings implicate σE and its regulon in E. coli extraintestinal pathogenesis.

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Biological Cost of Single and Multiple Norfloxacin Resistance Mutations in Escherichia coli Implicated in Urinary Tract Infections

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.6.2343-2351.2005 ◽

2005 ◽

Vol 49 (6) ◽

pp. 2343-2351 ◽

Cited By ~ 91

Author(s):

Patricia Komp Lindgren ◽

Linda L. Marcusson ◽

Dorthe Sandvang ◽

Niels Frimodt-Møller ◽

Diarmaid Hughes

Keyword(s):

Escherichia Coli ◽

Urinary Tract ◽

Infection Model ◽

Resistance Mutations ◽

Topoisomerase Iv ◽

E Coli ◽

Tract Infections ◽

Subsequent Selection

ABSTRACT Resistance to fluoroquinolones in urinary tract infection (UTIs) caused by Escherichia coli is associated with multiple mutations, typically those that alter DNA gyrase and DNA topoisomerase IV and those that regulate AcrAB-TolC-mediated efflux. We asked whether a fitness cost is associated with the accumulation of these multiple mutations. Mutants of the susceptible E. coli UTI isolate Nu14 were selected through three to five successive steps with norfloxacin. Each selection was performed with the MIC of the selected strain. After each selection the MIC was measured; and the regions of gyrA, gyrB, parC, and parE, previously associated with resistance mutations, and all of marOR and acrR were sequenced. The first selection step yielded mutations in gyrA, gyrB, and marOR. Subsequent selection steps yielded mutations in gyrA, parE, and marOR but not in gyrB, parC, or acrR. Resistance-associated mutations were identified in almost all isolates after selection steps 1 and 2 but in less than 50% of isolates after subsequent selection steps. Selected strains were competed in vitro, in urine, and in a mouse UTI infection model against the starting strain, Nu14. First-step mutations were not associated with significant fitness costs. However, the accumulation of three or more resistance-associated mutations was usually associated with a large reduction in biological fitness, both in vitro and in vivo. Interestingly, in some lineages a partial restoration of fitness was associated with the accumulation of additional mutations in late selection steps. We suggest that the relative biological costs of multiple mutations may influence the evolution of E. coli strains that develop resistance to fluoroquinolones.

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