scholarly journals fosIIs a New Integron-Associated Gene Cassette Encoding Reduced Susceptibility to Fosfomycin

2015 ◽  
Vol 60 (1) ◽  
pp. 686-688 ◽  
Author(s):  
Karla de Oliveira Pelegrino ◽  
Juliana Coutinho Campos ◽  
Suely Carlos Ferreira Sampaio ◽  
Karina Lezirovitz ◽  
Bruna Mara Seco ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Gene Cassette ◽  
Small Protein ◽  
Content Type ◽  
E Coli

ABSTRACTIn this work, we demonstrate that thefosIgene encodes a predicted small protein with 134 amino acids and determines reduced susceptibility to fosfomycin. It raised the MIC from 0.125 to 6 μg/ml when the pBRA100 plasmid was introduced intoEscherichia coliTOP10 and to 16 μg/ml when the gene was cloned into the pBC_SK(−) vector and expressed inE. coliTOP10.

scholarly journals Complex Physiology and Compound Stress Responses during Fermentation of Alkali-Pretreated Corn Stover Hydrolysate by an Escherichia coli Ethanologen

2012 ◽  
Vol 78 (9) ◽  
pp. 3442-3457 ◽  
Author(s):  
Michael S. Schwalbach ◽  
David H. Keating ◽  
Mary Tremaine ◽  
Wesley D. Marner ◽  
Yaoping Zhang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Amino Acids ◽  
Stationary Phase ◽  
Gene Expression Profiling ◽  
Stress Responses ◽  
Expression Profiling ◽  
Content Type ◽  
E Coli ◽  
Cell Maintenance

ABSTRACTThe physiology of ethanologenicEscherichia coligrown anaerobically in alkali-pretreated plant hydrolysates is complex and not well studied. To gain insight into howE. coliresponds to such hydrolysates, we studied anE. coliK-12 ethanologen fermenting a hydrolysate prepared from corn stover pretreated by ammonia fiber expansion. Despite the high sugar content (∼6% glucose, 3% xylose) and relatively low toxicity of this hydrolysate,E. coliceased growth long before glucose was depleted. Nevertheless, the cells remained metabolically active and continued conversion of glucose to ethanol until all glucose was consumed. Gene expression profiling revealed complex and changing patterns of metabolic physiology and cellular stress responses during an exponential growth phase, a transition phase, and the glycolytically active stationary phase. During the exponential and transition phases, high cell maintenance and stress response costs were mitigated, in part, by free amino acids available in the hydrolysate. However, after the majority of amino acids were depleted, the cells entered stationary phase, and ATP derived from glucose fermentation was consumed entirely by the demands of cell maintenance in the hydrolysate. Comparative gene expression profiling and metabolic modeling of the ethanologen suggested that the high energetic cost of mitigating osmotic, lignotoxin, and ethanol stress collectively limits growth, sugar utilization rates, and ethanol yields in alkali-pretreated lignocellulosic hydrolysates.

scholarly journals Heterologous Production of Cyanobacterial Mycosporine-Like Amino Acids Mycosporine-Ornithine and Mycosporine-Lysine in Escherichia coli

2016 ◽  
Vol 82 (20) ◽  
pp. 6167-6173 ◽  
Author(s):  
Meenu Katoch ◽  
Rabia Mazmouz ◽  
Rocky Chau ◽  
Leanne A. Pearson ◽  
Russell Pickford ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Heterologous Expression ◽  
Gene Cluster ◽  
Uv Radiation ◽  
Active Ingredient ◽  
Stress Factors ◽  
Heterologous Production ◽  
Content Type ◽  
E Coli

ABSTRACTMycosporine-like amino acids (MAAs) are an important class of secondary metabolites known for their protection against UV radiation and other stress factors. Cyanobacteria produce a variety of MAAs, including shinorine, the active ingredient in many sunscreen creams. Bioinformatic analysis of the genome of the soil-dwelling cyanobacteriumCylindrospermum stagnalePCC 7417 revealed a new gene cluster with homology to MAA synthase fromNostoc punctiforme. This newly identified gene cluster is unusual because it has five biosynthesis genes (mylAtomylE), compared to the four found in other MAA gene clusters. Heterologous expression ofmylAtomylEinEscherichia coliresulted in the production of mycosporine-lysine and the novel compound mycosporine-ornithine. To our knowledge, this is the first time these compounds have been heterologously produced inE. coliand structurally characterized via direct spectral guidance. This study offers insight into the diversity, biosynthesis, and structure of cyanobacterial MAAs and highlights their amenability to heterologous production methods.IMPORTANCEMycosporine-like amino acids (MAAs) are significant from an environmental microbiological perspective as they offer microbes protection against a variety of stress factors, including UV radiation. The heterologous expression of MAAs inE. coliis also significant from a biotechnological perspective as MAAs are the active ingredient in next-generation sunscreens.

scholarly journals Members of the Conserved DedA Family Are Likely Membrane Transporters and Are Required for Drug Resistance in Escherichia coli

2013 ◽  
Vol 58 (2) ◽  
pp. 923-930 ◽  
Author(s):  
Sujeet Kumar ◽  
William T. Doerrler
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Drug Resistance ◽  
Public Health Problem ◽  
Membrane Transporters ◽  
Wild Type ◽  
Content Type ◽  
E Coli ◽  
Acidic Amino Acids ◽  
Genes Encoding

ABSTRACTBacterial resistance to antibiotics and biocides is an increasing public health problem. Genes encoding integral membrane proteins belonging to the DedA family are present in most bacterial genomes, includingEscherichia coli. AnE. colistrain lacking partially redundant DedA family genesyqjAandyghB(strain BC202) displays temperature sensitivity and cell division defects. These phenotypes can be corrected by overexpression ofmdfA, an Na+-K+/H+antiporter of the major facilitator superfamily. We show that BC202 is hypersensitive to several biocides and cationic compounds that are known substrates of several multidrug resistance transporters, including MdfA, EmrE, and AcrB. The introduction of deletions of genes encoding these drug transporters into BC202 results in additional sensitivity. Expression of wild-typeyghBoryqjAcan restore drug resistance, but this is eliminated upon mutation of two membrane-embedded acidic amino acids (E39 or D51 in either protein). This dependence upon membrane-embedded acidic amino acids is a hallmark of proton-dependent antiporters. Overexpression ofmdfAin BC202 or artificially restoring proton motive force (PMF) restores wild-type resistance to substrates of MdfA as well as other drug resistance transporters such as EmrE and AcrAB. These results suggest that YqjA and YghB may be membrane transporters required for PMF-dependent drug efflux inE. coli.

scholarly journals Molecular Characterization of Multidrug-Resistant Escherichia coli Isolates from Irish Cattle Farms

2011 ◽  
Vol 77 (20) ◽  
pp. 7121-7127 ◽  
Author(s):  
Maria Karczmarczyk ◽  
Ciara Walsh ◽  
Rosemarie Slowey ◽  
Nola Leonard ◽  
Séamus Fanning
Keyword(s):  
Escherichia Coli ◽  
Gene Cassette ◽  
Multidrug Resistant ◽  
Gene Markers ◽  
Variable Regions ◽  
Content Type ◽  
E Coli ◽  
Virulence Markers ◽  
Class 1 ◽  
Genotypic Characteristics

ABSTRACTThis study describes the genotypic characteristics of a collection of 100 multidrug-resistant (MDR)Escherichia colistrains recovered from cattle and the farm environment in Ireland in 2007. The most prevalent antimicrobial resistance identified was to streptomycin (100%), followed by tetracycline (99%), sulfonamides (98%), ampicillin (82%), and neomycin (62%). Resistance was mediated predominantly bystrA-strB(92%),tetA(67%),sul2(90%),blaTEM(79%), andaphA1(63%) gene markers, respectively. Twenty-seven isolates harbored a class 1 integrase (intI1), whileqacEΔ1andsul1markers were identified in 25 and 26 isolates, respectively. The variable regions of these integrons contained aminoglycoside, trimethoprim, and β-lactam resistance determinants (aadA12,aadB-aadA1,blaOXA-30-aadA1,dfrA1-aadA1,dfrA7). Class 2 integrons were identified less frequently (4%) and contained the gene cassette arraydfrA1-sat1-aadA1. Resistance to ampicillin, neomycin, streptomycin, sulfonamide, and tetracycline was associated with transferable high-molecular-weight plasmids, as demonstrated by conjugation assays. A panel of virulence markers was screened for by PCR, and genes identified includedvt1, K5 in 2 isolates,papCin 10 isolates, and PAI IV536in 37 isolates. MDR commensalE. coliisolates from Irish cattle displayed considerable diversity with respect to the genes identified. Our findings highlight the importance of the commensal microflora of food-producing animals as a reservoir of transferable MDR.

scholarly journals Escherichia coli K-12 Lacks a High-Affinity Assimilatory Cysteine Importer

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Yidan Zhou ◽  
James A. Imlay
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Chemical Reactivity ◽  
Enteric Bacteria ◽  
Natural Environments ◽  
Content Type ◽  
E Coli ◽  
High Affinity ◽  
Anoxic Environments ◽  
K 12

ABSTRACT The most direct route by which microbes might assimilate sulfur would be by importing cysteine. However, alone among the amino acids, cysteine does not have well-characterized importers. We determined that Escherichia coli can rapidly import cysteine, but in our experiments, it did so primarily through the LIV ATP-driven system that is dedicated to branched-chain amino acids. The affinity of this system for cysteine is far lower than for Leu, Ile, and Val, and so in their presence, cysteine is excluded. Thus, this transport is unlikely to be relevant in natural environments. Growth studies, transcriptomics, and transport assays failed to detect any high-affinity importer that is dedicated to cysteine assimilation. Enteric bacteria do not contain the putative cysteine importer that was identified in Campylobacter jejuni. This situation is surprising, because E. coli deploys ion- and/or ATP-driven transporters that import cystine, the oxidized form of cysteine, with high affinity and specificity. We conjecture that in oxic environments, molecular oxygen oxidizes environmental cysteine to cystine, which E. coli imports. In anoxic environments where cysteine is stable, the cell chooses to assimilate hydrogen sulfide instead. Calculations suggest that this alternative is almost as economical, and it avoids the toxic effects that can result when excess cysteine enters the cell. IMPORTANCE This investigation discovered that Escherichia coli lacks a transporter dedicated to the assimilation of cysteine, an outcome that is in striking contrast to the many transporters devoted to the other 19 amino acids. We ascribe the lack of a high-affinity cysteine importer to two considerations. First, the chemical reactivity of this amino acid is unique, and its poorly controlled import can have adverse consequences for the cell. Second, our analysis suggests that the economics of biosynthesis depend sharply upon whether the cell is respiring or fermenting. In the anoxic habitats in which cysteine might be found, the value of import versus biosynthesis is strongly reduced compared to that in oxic habitats. These studies may explain why bacteria choose to synthesize rather than to import other useful biomolecules as well.

scholarly journals Osmotolerance in Escherichia coli Is Improved by Activation of Copper Efflux Genes or Supplementation with Sulfur-Containing Amino Acids

2017 ◽  
Vol 83 (7) ◽  
Author(s):  
Mengyong Xiao ◽  
Xinna Zhu ◽  
Feiyu Fan ◽  
Hongtao Xu ◽  
Jinlei Tang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Osmotic Stress ◽  
Cell Mass ◽  
Anaerobic Conditions ◽  
Two Component System ◽  
Content Type ◽  
E Coli ◽  
Sulfur Containing ◽  
Disodium Succinate

ABSTRACT Improvement in the osmotolerance of Escherichia coli is essential for the production of high titers of various bioproducts. In this work, a cusS mutation that was identified in the previously constructed high-succinate-producing E. coli strain HX024 was investigated for its effect on osmotolerance. CusS is part of the two-component system CusSR that protects cells from Ag(I) and Cu(I) toxicity. Changing cusS from strain HX024 back to its original sequence led to a 24% decrease in cell mass and succinate titer under osmotic stress (12% glucose). When cultivated with a high initial glucose concentration (12%), introduction of the cusS mutation into parental strain Suc-T110 led to a 21% increase in cell mass and a 40% increase in succinate titer. When the medium was supplemented with 30 g/liter disodium succinate, the cusS mutation led to a 120% increase in cell mass and a 492% increase in succinate titer. Introducing the cusS mutation into the wild-type strain ATCC 8739 led to increases in cell mass of 87% with 20% glucose and 36% using 30 g/liter disodium succinate. The cusS mutation increased the expression of cusCFBA, and gene expression levels were found to be positively related to osmotolerance abilities. Because high osmotic stress has been associated with deleterious accumulation of Cu(I) in the periplasm, activation of CusCFBA may alleviate this effect by transporting Cu(I) out of the cells. This hypothesis was confirmed by supplementing sulfur-containing amino acids that can chelate Cu(I). Adding methionine or cysteine to the medium increased the osmotolerance of E. coli under anaerobic conditions. IMPORTANCE In this work, an activating Cus copper efflux system was found to increase the osmotolerance of E. coli. In addition, new osmoprotectants were identified. Supplementation with methionine or cysteine led to an increase in osmotolerance of E. coli under anaerobic conditions. These new strategies for improving osmotolerance will be useful for improving the production of chemicals in industrial bioprocesses.

scholarly journals Tailoring a Global Iron Regulon to a Uropathogen

mBio ◽  
2020 ◽  
Vol 11 (2) ◽  
Author(s):  
Rajdeep Banerjee ◽  
Erin Weisenhorn ◽  
Kevin J. Schwartz ◽  
Kevin S. Myers ◽  
Jeremy D. Glasner ◽  
...  
Keyword(s):  
Amino Acids ◽  
Urinary Tract ◽  
Amino Acid ◽  
Regulatory Network ◽  
Iron Homeostasis ◽  
Iron Limitation ◽  
Content Type ◽  
E Coli ◽  
General Stress ◽  
K 12

ABSTRACT Pathogenicity islands and plasmids bear genes for pathogenesis of various Escherichia coli pathotypes. Although there is a basic understanding of the contribution of these virulence factors to disease, less is known about variation in regulatory networks in determining disease phenotypes. Here, we dissected a regulatory network directed by the conserved iron homeostasis regulator, ferric uptake regulator (Fur), in uropathogenic E. coli (UPEC) strain CFT073. Comparing anaerobic genome-scale Fur DNA binding with Fur-dependent transcript expression and protein levels of the uropathogen to that of commensal E. coli K-12 strain MG1655 showed that the Fur regulon of the core genome is conserved but also includes genes within the pathogenicity/genetic islands. Unexpectedly, regulons indicative of amino acid limitation and the general stress response were also indirectly activated in the uropathogen fur mutant, suggesting that induction of the Fur regulon increases amino acid demand. Using RpoS levels as a proxy, addition of amino acids mitigated the stress. In addition, iron chelation increased RpoS to the same levels as in the fur mutant. The increased amino acid demand of the fur mutant or iron chelated cells was exacerbated by aerobic conditions, which could be partly explained by the O2-dependent synthesis of the siderophore aerobactin, encoded by an operon within a pathogenicity island. Taken together, these data suggest that in the iron-poor environment of the urinary tract, amino acid availability could play a role in the proliferation of this uropathogen, particularly if there is sufficient O2 to produce aerobactin. IMPORTANCE Host iron restriction is a common mechanism for limiting the growth of pathogens. We compared the regulatory network controlled by Fur in uropathogenic E. coli (UPEC) to that of nonpathogenic E. coli K-12 to uncover strategies that pathogenic bacteria use to overcome iron limitation. Although iron homeostasis functions were regulated by Fur in the uropathogen as expected, a surprising finding was the activation of the stringent and general stress responses in the uropathogen fur mutant, which was rescued by amino acid addition. This coordinated global response could be important in controlling growth and survival under nutrient-limiting conditions and during transitions from the nutrient-rich environment of the lower gastrointestinal (GI) tract to the more restrictive environment of the urinary tract. The coupling of the response of iron limitation to increased demand for amino acids could be a critical attribute that sets UPEC apart from other E. coli pathotypes.

scholarly journals Isolation of a Gene Responsible for the Oxidation oftrans-Anethole topara-Anisaldehyde by Pseudomonas putida JYR-1 and Its Expression in Escherichia coli

2012 ◽  
Vol 78 (15) ◽  
pp. 5238-5246 ◽  
Author(s):  
Dongfei Han ◽  
Ji-Young Ryu ◽  
Robert A. Kanaly ◽  
Hor-Gil Hur
Keyword(s):  
Escherichia Coli ◽  
Pseudomonas Putida ◽  
Hypothetical Protein ◽  
Aldehyde Group ◽  
Agrobacterium Vitis ◽  
T7 Promoter ◽  
Content Type ◽  
E Coli ◽  
Cell Extracts ◽  
Isoeugenol Monooxygenase

ABSTRACTA plasmid, pTA163, inEscherichia colicontained an approximately 34-kb gene fragment fromPseudomonas putidaJYR-1 that included the genes responsible for the metabolism oftrans-anethole to protocatechuic acid. Three Tn5-disrupted open reading frame 10 (ORF 10) mutants of plasmid pTA163 lost their abilities to catalyzetrans-anethole. Heterologously expressed ORF 10 (1,047 nucleotides [nt]) under a T7 promoter inE. colicatalyzed oxidative cleavage of a propenyl group oftrans-anethole to an aldehyde group, resulting in the production ofpara-anisaldehyde, and this gene was designatedtao(trans-anetholeoxygenase). The deduced amino acid sequence of TAO had the highest identity (34%) to a hypothetical protein ofAgrobacterium vitisS4 and likely contained a flavin-binding site. Preferred incorporation of an oxygen molecule from water intop-anisaldehyde using18O-labeling experiments indicated stereo preference of TAO for hydrolysis of the epoxide group. Interestingly, unlike the narrow substrate range of isoeugenol monooxygenase fromPseudomonas putidaIE27 andPseudomonas nitroreducensJin1, TAO fromP. putidaJYR-1 catalyzed isoeugenol,O-methyl isoeugenol, and isosafrole, all of which contain the 2-propenyl functional group on the aromatic ring structure. Addition of NAD(P)H to the ultrafiltered cell extracts ofE. coli(pTA163) increased the activity of TAO. Due to the relaxed substrate range of TAO, it may be utilized for the production of various fragrance compounds from plant phenylpropanoids in the future.

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 Autotransporter Protein-Encoding Genes of Diarrheagenic Escherichia coli Are Found in both Typical and Atypical Enteropathogenic E. coli Strains

2012 ◽  
Vol 79 (1) ◽  
pp. 411-414 ◽  
Author(s):  
Afonso G. Abreu ◽  
Vanessa Bueris ◽  
Tatiane M. Porangaba ◽  
Marcelo P. Sircili ◽  
Fernando Navarro-Garcia ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Content Type ◽  
E Coli ◽  
Diarrheagenic Escherichia Coli ◽  
Virulence Markers ◽  
Protein Encoding ◽  
Encoding Genes ◽  
Specific Virulence

ABSTRACTAutotransporter (AT) protein-encoding genes of diarrheagenicEscherichia coli(DEC) pathotypes (cah,eatA,ehaABCDJ,espC,espI,espP,pet,pic,sat, andtibA) were detected in typical and atypical enteropathogenicE. coli(EPEC) in frequencies between 0.8% and 39.3%. Although these ATs have been described in particular DEC pathotypes, their presence in EPEC indicates that they should not be considered specific virulence markers.

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