scholarly journals The rfaE Gene from Escherichia coli Encodes a Bifunctional Protein Involved in Biosynthesis of the Lipopolysaccharide Core Precursor ADP-l-glycero-d-manno-Heptose

2000 ◽  
Vol 182 (2) ◽  
pp. 488-497 ◽  
Author(s):  
Miguel A. Valvano ◽  
Cristina L. Marolda ◽  
Mauricio Bittner ◽  
Mike Glaskin-Clay ◽  
Tania L. Simon ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Inner Core ◽  
Structural Features ◽  
Predicted Amino Acid Sequence ◽  
E Coli ◽  
K 12 ◽  
Domain I

ABSTRACT The intermediate steps in the biosynthesis of the ADP-l-glycero-d-manno-heptose precursor of inner core lipopolysaccharide (LPS) are not yet elucidated. We isolated a mini-Tn10 insertion that confers a heptoseless LPS phenotype in the chromosome of Escherichia coli K-12. The mutation was in a gene homologous to the previously reported rfaE gene from Haemophilus influenzae. The E. coli rfaE gene was cloned into an expression vector, and an in vitro transcription-translation experiment revealed a polypeptide of approximately 55 kDa in mass. Comparisons of the predicted amino acid sequence with other proteins in the database showed the presence of two clearly separate domains. Domain I (amino acids 1 to 318) shared structural features with members of the ribokinase family, while Domain II (amino acids 344 to 477) had conserved features of the cytidylyltransferase superfamily that includes the aut gene product of Ralstonia eutrophus. Each domain was expressed individually, demonstrating that only Domain I could complement therfaE::Tn10 mutation in E. coli, as well as the rfaE543 mutation ofSalmonella enterica SL1102. DNA sequencing of therfaE543 gene revealed that Domain I had one amino acid substitution and a 12-bp in-frame deletion resulting in the loss of four amino acids, while Domain II remained intact. We also demonstrated that the aut::Tn5 mutation inR. eutrophus is associated with heptoseless LPS, and this phenotype was restored following the introduction of a plasmid expressing the E. coli Domain II. Thus, both domains ofrfaE are functionally different and genetically separable confirming that the encoded protein is bifunctional. We propose that Domain I is involved in the synthesis ofd-glycero-d-manno-heptose 1-phosphate, whereas Domain II catalyzes the ADP transfer to form ADP-d-glycero-d-manno-heptose.

scholarly journals The yefM-yoeB Toxin-Antitoxin Systems of Escherichia coli and Streptococcus pneumoniae: Functional and Structural Correlation

2006 ◽  
Vol 189 (4) ◽  
pp. 1266-1278 ◽  
Author(s):  
Concha Nieto ◽  
Izhack Cherny ◽  
Seok Kooi Khoo ◽  
Mario García de Lacoba ◽  
Wai Ting Chan ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Streptococcus Pneumoniae ◽  
Structural Features ◽  
E Coli ◽  
Modeled Structure ◽  
The Family ◽  
Bona Fide ◽  
K 12

ABSTRACT Toxin-antitoxin loci belonging to the yefM-yoeB family are located in the chromosome or in some plasmids of several bacteria. We cloned the yefM-yoeB locus of Streptococcus pneumoniae, and these genes encode bona fide antitoxin (YefM Spn ) and toxin (YoeB Spn ) products. We showed that overproduction of YoeB Spn is toxic to Escherichia coli cells, leading to severe inhibition of cell growth and to a reduction in cell viability; this toxicity was more pronounced in an E. coli B strain than in two E. coli K-12 strains. The YoeB Spn -mediated toxicity could be reversed by the cognate antitoxin, YefM Spn , but not by overproduction of the E. coli YefM antitoxin. The pneumococcal proteins were purified and were shown to interact with each other both in vitro and in vivo. Far-UV circular dichroism analyses indicated that the pneumococcal antitoxin was partially, but not totally, unfolded and was different than its E. coli counterpart. Molecular modeling showed that the toxins belonging to the family were homologous, whereas the antitoxins appeared to be specifically designed for each bacterial locus; thus, the toxin-antitoxin interactions were adapted to the different bacterial environmental conditions. Both structural features, folding and the molecular modeled structure, could explain the lack of cross-complementation between the pneumococcal and E. coli antitoxins.

scholarly journals DsdX Is the Second d-Serine Transporter in Uropathogenic Escherichia coli Clinical Isolate CFT073

2006 ◽  
Vol 188 (18) ◽  
pp. 6622-6628 ◽  
Author(s):  
Andrew T. Anfora ◽  
Rodney A. Welch
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Carbon Source ◽  
Clinical Isolate ◽  
Sole Carbon Source ◽  
Minimal Medium ◽  
Amino Acid Sequence Similarity ◽  
Predicted Amino Acid Sequence ◽  
E Coli ◽  
K 12

ABSTRACTd-Serine is an amino acid present in mammalian urine that is inhibitory toEscherichia colistrains lacking a functionaldsdAgene. Counterintuitively, adsdAstrain ofE. coliclinical isolate CFT073 hypercolonizes the bladder and kidneys of mice relative to wild type during a coinfection in the murine model of urinary tract infection. We are interested in the mechanisms for uptake ofd-serine in CFT073.d-Serine entersE. coliK-12 via CycA, thed-alanine transporter andd-cycloserine sensitivity locus. CFT073cycAcan grow on minimal medium withd-serine as a sole carbon source. ThedsdXgene of thedsdCXAlocus is a likely candidate for an additionald-serine transporter based on its predicted amino acid sequence similarity to gluconate transporters. In minimal medium, CFT073dsdXcan grow ond-serine as a sole carbon source; however, CFT073dsdX cycAcannot. Additionally, CFT073dsdXA cycAis not sensitive to inhibitory concentrations ofd-serine during growth on glycerol andd-serine minimal medium.d-[14C]serine uptake experiments with CFT073dsdX cycAharboringdsdXorcycArecombinant plasmids confirm thatd-serine is able to enterE. colicells via CycA or DsdX. In whole-celld-[14C]serine uptake experiments, DsdX has an apparentKmof 58.75 μM and aVmaxof 75.96 nmol/min/mg, and CycA has an apparentKmof 82.40 μM and aVmaxof 58.90 nmol/min/mg. Onlyd-threonine marginally inhibits DsdX-mediatedd-serine transport, whereasd-alanine, glycine, andd-cycloserine inhibit CycA-mediatedd-serine transport. DsdX or CycA is sufficient to transport physiological quantities ofd-serine, but DsdX is ad-serine-specific permease.

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 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.

Subunit II (b') and Not Subunit I (b) of Photosynthetic ATP Synthases is Equivalent to Subunit b of the ATP Synthases from Nonphotosynthetic Eubacteria. Evidence for a New Assignment of b-Type F0 Subunits

1997 ◽  
Vol 52 (11-12) ◽  
pp. 789-798 ◽  
Author(s):  
Hans-Jürgen Tiburzy ◽  
Richard J. Berzborn
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Structural Feature ◽  
Atp Synthase ◽  
Primary Structure ◽  
Structural Features ◽  
Amino Acid Sequences ◽  
E Coli ◽  
Subunit B ◽  
Atp Synthases

Abstract Subunit I of chloroplast ATP synthase is reviewed until now to be equivalent to subunit b of Escherichia coli ATP synthase, whereas subunit II is suggested to be an additional subunit in photosynthetic ATP synthases lacking a counterpart in E. coli. After publication of some sequences of subunits II a revision of this assignment is necessary. Based on the analysis of 51 amino acid sequences of b-type subunits concerning similarities in primary structure, iso­electric point and a discovered discontinuous structural feature, our data provide evidence that chloroplast subunit II (subunit b' of photosynthetic eubacteria) and not chloroplast subunit I (subunit b of photosynthetic eubacteria) is the equivalent of subunit b of nonphoto­ synthetic eubacteria, and therefore does have a counterpart in e.g. E. coli. In consequence, structural features essential for function should be looked for on subunit II (b').

scholarly journals Advantage of the F2:A1:B- IncF Pandemic Plasmid over IncC Plasmids in In Vitro Acquisition and Evolution of blaCTX-M Gene-Bearing Plasmids in Escherichia coli

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Anne-Claire Mahérault ◽  
Harry Kemble ◽  
Mélanie Magnan ◽  
Benoit Gachet ◽  
David Roche ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Experimental Evolution ◽  
Negative Impact ◽  
Fitness Cost ◽  
M Gene ◽  
Content Type ◽  
E Coli ◽  
Conjugative Plasmids ◽  
K 12

ABSTRACT Despite a fitness cost imposed on bacterial hosts, large conjugative plasmids play a key role in the diffusion of resistance determinants, such as CTX-M extended-spectrum β-lactamases. Among the large conjugative plasmids, IncF plasmids are the most predominant group, and an F2:A1:B- IncF-type plasmid encoding a CTX-M-15 variant was recently described as being strongly associated with the emerging worldwide Escherichia coli sequence type 131 (ST131)-O25b:H4 H30Rx/C2 sublineage. In this context, we investigated the fitness cost of narrow-range F-type plasmids, including the F2:A1:B- IncF-type CTX-M-15 plasmid, and of broad-range C-type plasmids in the K-12-like J53-2 E. coli strain. Although all plasmids imposed a significant fitness cost to the bacterial host immediately after conjugation, we show, using an experimental-evolution approach, that a negative impact on the fitness of the host strain was maintained throughout 1,120 generations with the IncC-IncR plasmid, regardless of the presence or absence of cefotaxime, in contrast to the F2:A1:B- IncF plasmid, whose cost was alleviated. Many chromosomal and plasmid rearrangements were detected after conjugation in transconjugants carrying the IncC plasmids but not in transconjugants carrying the F2:A1:B- IncF plasmid, except for insertion sequence (IS) mobilization from the fliM gene leading to the restoration of motility of the recipient strains. Only a few mutations occurred on the chromosome of each transconjugant throughout the experimental-evolution assay. Our findings indicate that the F2:A1:B- IncF CTX-M-15 plasmid is well adapted to the E. coli strain studied, contrary to the IncC-IncR CTX-M-15 plasmid, and that such plasmid-host adaptation could participate in the evolutionary success of the CTX-M-15-producing pandemic E. coli ST131-O25b:H4 lineage.

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 Adaptation in a Mouse Colony Monoassociated with Escherichia coli K-12 for More than 1,000 Days

2010 ◽  
Vol 76 (14) ◽  
pp. 4655-4663 ◽  
Author(s):  
Sean M. Lee ◽  
Aaron Wyse ◽  
Aaron Lesher ◽  
Mary Lou Everett ◽  
Linda Lou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Rates ◽  
Bacterial Species ◽  
Intestinal Flora ◽  
Average Density ◽  
Host Bacterium ◽  
E Coli ◽  
K 12

ABSTRACT Although mice associated with a single bacterial species have been used to provide a simple model for analysis of host-bacteria relationships, bacteria have been shown to display adaptability when grown in a variety of novel environments. In this study, changes associated with the host-bacterium relationship in mice monoassociated with Escherichia coli K-12 over a period of 1,031 days were evaluated. After 80 days, phenotypic diversification of E. coli was observed, with the colonizing bacteria having a broader distribution of growth rates in the laboratory than the parent E. coli. After 1,031 days, which included three generations of mice and an estimated 20,000 generations of E. coli, the initially homogeneous bacteria colonizing the mice had evolved to have widely different growth rates on agar, a potential decrease in tendency for spontaneous lysis in vivo, and an increased tendency for spontaneous lysis in vitro. Importantly, mice at the end of the experiment were colonized at an average density of bacteria that was more than 3-fold greater than mice colonized on day 80. Evaluation of selected isolates on day 1,031 revealed unique restriction endonuclease patterns and differences between isolates in expression of more than 10% of the proteins identified by two-dimensional electrophoresis, suggesting complex changes underlying the evolution of diversity during the experiment. These results suggest that monoassociated mice might be used as a tool for characterizing niches occupied by the intestinal flora and potentially as a method of targeting the evolution of bacteria for applications in biotechnology.

scholarly journals Enzymic synthesis of N-acetyl-l-phenylalanine in Escherichia coli K12

1971 ◽  
Vol 124 (5) ◽  
pp. 905-913 ◽  
Author(s):  
R. V. Krishna ◽  
P. R. Krishnaswamy ◽  
D. Rajagopal Rao
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
E Coli ◽  
Enzymic Synthesis ◽  
Escherichia Coli K12

1. Cell-free extracts of Escherichia coli K12 catalyse the synthesis of N-acetyl-l-phenylalanine from acetyl-CoA and l-phenylalanine. 2. The acetyl-CoA–l-phenylalanine α-N-acetyltransferase was purified 160-fold from cell-free extracts. 3. The enzyme has a pH optimum of 8 and catalyses the acetylation of l-phenylalanine. Other l-amino acids such as histidine and alanine are acetylated at slower rates. 4. A transacylase was also purified from E. coli extracts and its substrate specificity studied. 5. The properties of both these enzymes were compared with those of other known amino acid acetyltransferases and transacylases.

scholarly journals LamB, OmpC, and the Core Lipopolysaccharide of Escherichia coli K-12 Function as Receptors of Bacteriophage Bp7

2020 ◽  
Vol 94 (12) ◽  
Author(s):  
Peipei Chen ◽  
Huzhi Sun ◽  
Huiying Ren ◽  
Wenhua Liu ◽  
Guimei Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Host Range ◽  
Inner Core ◽  
Phage Infection ◽  
Broad Host Range ◽  
Content Type ◽  
E Coli ◽  
Phage Adsorption ◽  
Specific Receptors ◽  
K 12

ABSTRACT Bp7 is a T-even phage with a broad host range specific to Escherichia coli, including E. coli K-12. The receptor binding protein (RBP) of bacteriophages plays an important role in the phage adsorption process and determines phage host range, but the molecular mechanism involved in host recognition of phage Bp7 remains unknown. In this study, the interaction between phage Bp7 and E. coli K-12 was investigated. Based on homology alignment, amino acid sequence analysis, and a competitive assay, gp38, located at the tip of the long tail fiber, was identified as the RBP of phage Bp7. Using a combination of in vivo and in vitro approaches, including affinity chromatography, gene knockout mutagenesis, a phage plaque assay, and phage adsorption kinetics analysis, we identified the LamB and OmpC proteins on the surface of E. coli K-12 as specific receptors involved in the first step of reversible phage adsorption. Genomic analysis of the phage-resistant mutant strain E. coli K-12-R and complementation tests indicated that HepI of the inner core of polysaccharide acts as the second receptor recognized by phage Bp7 and is essential for successful phage infection. This observation provides an explanation of the broad host range of phage Bp7 and provides insight into phage-host interactions. IMPORTANCE The RBPs of T4-like phages are gp37 and gp38. The interaction between phage T4 RBP gp37 and its receptors has been clarified by many reports. However, the interaction between gp38 and its receptors during phage adsorption is still not completely understood. Here, we identified phage Bp7, which uses gp38 as an RBP, and provided a good model to study the phage-host interaction mechanisms in an enterobacteriophage. Our study revealed that gp38 of phage Bp7 recognizes the outer membrane proteins (OMPs) LamB and OmpC of E. coli K-12 as specific receptors and binds with them reversibly. HepI of the inner-core oligosaccharide is the second receptor and binds with phage Bp7 irreversibly to begin the infection process. Determining the interaction between the phage and its receptors will help elucidate the mechanisms of phage with a broad host range and help increase understanding of the phage infection mechanism based on gp38.

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