Journal of Microbiology

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Comparative Secretory Efficiency of Two Chitosanase Signal Peptides from Bacillus subtilis in Escherichia coli: Tae-Yang Eom, Yehui Gang, Youngdeuk Lee, Yoon-Hyeok Kang, Eunyoung Jo, Svini Dileepa Marasinghe, Heung Sik Park, Gun-Hoo Park, Chulhong Oh; J. Microbiol. 2024;62(12):1155-1164. Published online November 25, 2024; DOI: https://doi.org/10.1007/s12275-024-00186-1

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Abstract: The production of recombinant proteins in Escherichia coli is often challenged by cytoplasmic expression due to proteolytic degradation and inclusion body formation. Extracellular expression can overcome these problems by simplifying downstream processing and improving protein yields. This study aims to compare the efficiency of two Bacillus subtilis chitosanase signal peptides in mediating extracellular secretion in E. coli. We identified a naturally occurring mutant signal peptide (mCsn2-SP) from B. subtilis CH2 chitosanase (CH2CSN), which is characterized by a deletion of six amino acids in the N-region relative to the signal peptide (Csn1-SP) from B. subtilis CH1 chitosanase (CH1CSN). The CH1CSN and CH2CSN genes were cloned into the pET-11a vector and protein secretion was evaluated in E. coli BL21(DE3) host cells. Expression was induced with 0.1 mM and 1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG) at 30 °C for one and three days. CH2CSN showed higher secretion levels compared to CH1CSN under all experimental conditions, especially with 0.1 mM IPTG induction for 3 days, which resulted in a 2.37-fold increase in secretion. Furthermore, it was demonstrated that mCsn2-SP is capable of secreting human Cu,Zn-superoxide dismutase (hSOD) in E. coli BL21(DE3) and successfully translocating it to the periplasmic region. This study represents the inaugural investigation into the utilisation of a naturally modified signal peptide, thereby corroborating the assertion that signal peptide deletion variants can influence protein secretion efficiency. Furthermore, the findings substantiate the proposition that such variants can serve as a viable alternative for the secretion of heterologous proteins in E. coli.

Relaxed Cleavage Specificity of Hyperactive Variants of Escherichia coli RNase E on RNA I: Dayeong Bae , Hana Hyeon , Eunkyoung Shin , Ji&# , Kangseok Lee; J. Microbiol. 2023;61(2):211-220. Published online February 22, 2023; DOI: https://doi.org/10.1007/s12275-023-00013-z

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RNase E is an essential enzyme in Escherichia coli. The cleavage site of this single-stranded specific endoribonuclease is well-characterized in many RNA substrates. Here, we report that the upregulation of RNase E cleavage activity by a mutation that affects either RNA binding (Q36R) or enzyme multimerization (E429G) was accompanied by relaxed cleavage specificity. Both mutations led to enhanced RNase E cleavage in RNA I, an antisense RNA of ColE1-type plasmid replication, at a major site and other cryptic sites. Expression of a truncated RNA I with a major RNase E cleavage site deletion at the 5′-end (RNA I- 5) resulted in an approximately twofold increase in the steady-state levels of RNA I- 5 and the copy number of ColE1-type plasmid in E. coli cells expressing wild-type or variant RNase E compared to those expressing RNA I. These
results
indicate that RNA I- 5 does not efficiently function as an antisense RNA despite having a triphosphate group at the 5′-end, which protects the RNA from ribonuclease attack. Our study suggests that increased cleavage rates of RNase E lead to relaxed cleavage specificity on RNA I and the inability of the cleavage product of RNA I as an antisense regulator in vivo does not stem from its instability by having 5′-monophosphorylated end.

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Engineering an Escherichia coli based in vivo mRNA manufacturing platform
Edward Curry, George Muir, Jixin Qu, Zoltán Kis, Martyn Hulley, Adam Brown
Biotechnology and Bioengineering.2024; 121(6): 1912. CrossRef

Amino acid residues in the Ler protein critical for derepression of the LEE5 promoter in enteropathogenic E. coli: Su-Mi Choi , Jae-Ho Jeong , Hyon E. Choy , Minsang Shin; J. Microbiol. 2016;54(8):559-564. Published online August 2, 2016; DOI: https://doi.org/10.1007/s12275-016-6027-6

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Abstract

Enteropathogenic E. coli causes attaching and effacing (A/E) intestinal lesions. The genes involved in the formation of A/E lesions are encoded within a chromosomal island comprising of five major operons, LEE1-5. The global regulator H-NS represses the expression of these operons. Ler, a H-NS homologue, counteracts the H-NS–mediated repression. Using a novel genetic approach, we identified the amino acid residues in Ler that are involved in the interaction with H-NS: I20 and L23 in the C-terminal portion of α-helix 3, and I42 in the following unstructured linker region.

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Regulation of the Locus of Enterocyte Effacement in Attaching and Effacing Pathogens
R. Christopher D. Furniss, Abigail Clements, William Margolin
Journal of Bacteriology.2018;[Epub] CrossRef

Research Support, Non-U.S. Gov'ts

Effect of promoter-upstream sequence on σ38-dependent stationary phase gene transcription: Hyung-Ju Lim , Kwangsoo Kim , Minsang Shin , Jae-Ho Jeong , Phil Youl Ryu , Hyon E. Choy; J. Microbiol. 2015;53(4):250-255. Published online April 8, 2015; DOI: https://doi.org/10.1007/s12275-015-4681-8

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Abstract

σ38 in Escherichia coli is required for expression of a subset of stationary phase genes. However, the promoter elements for σ38-dependent genes are virtually indistinguishable from that for σ70-dependent house-keeping genes. hdeABp is a σ38-dependent promoter and LEE5p is a σ70-dependent promoter, but both are repressed by H-NS, a bacterial histone- like protein, which acts at promoter upstream sequence. We swapped the promoter upstream sequences of the two promoters and found that the σ dependency was switched. This was further verified using lacUV5 core promoter. The
results
suggested that the determinant for σ38-dependent promoter lies in the promoter upstream sequence.

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Sequence-dependent model of genes with dual σ factor preference
Ines S.C. Baptista, Vinodh Kandavalli, Vatsala Chauhan, Mohamed N.M. Bahrudeen, Bilena L.B. Almeida, Cristina S.D. Palma, Suchintak Dash, Andre S. Ribeiro
Biochimica et Biophysica Acta (BBA) - Gene Regulatory Mechanisms.2022; 1865(3): 194812. CrossRef
Function Enhancement of a Metabolic Module via Endogenous Promoter Replacement for Pseudomonas sp. JY-Q to Degrade Nicotine in Tobacco Waste Treatment
Jun Li, Fengmei Yi, Guoqing Chen, Fanda Pan, Yang Yang, Ming Shu, Zeyu Chen, Zeling Zhang, Xiaotong Mei, Weihong Zhong
Applied Biochemistry and Biotechnology.2021; 193(9): 2793. CrossRef
Recent advances in genetic engineering tools based on synthetic biology
Jun Ren, Jingyu Lee, Dokyun Na
Journal of Microbiology.2020; 58(1): 1. CrossRef

Low-Scale Expression and Purification of an Active Putative Iduronate 2-Sulfate Sulfatase-Like Enzyme from Escherichia coli K12: Edwin David Morales-Álvarez , Claudia Marcela Rivera-Hoyos , Angélica María Baena-Moncada , Patricia Landázuri , Raúl A. Poutou-Piñales , Homero Sáenz-Suárez , Luis A. Barrera , Olga Y. Echeverri-Peña; J. Microbiol. 2013;51(2):213-221. Published online April 27, 2013; DOI: https://doi.org/10.1007/s12275-013-2416-2

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Abstract: The sulfatase family involves a group of enzymes with a large degree of similarity. Until now, sixteen human sulfatases have been identified, most of them found in lysosomes. Human deficiency of sulfatases generates various genetic disorders characterized by abnormal accumulation of sulfated intermediate compounds. Mucopolysaccharidosis type II is characterized by the deficiency of iduronate 2-sulfate sulfatase (IDS), causing the lysosomal accumulation of heparan and dermatan sulfates. Currently, there are several cases of genetic diseases treated with enzyme replacement therapy, which have generated a great interest in the development of systems for recombinant protein expression. In this work we expressed the human recombinant IDS-Like enzyme (hrIDS-Like) in Escherichia coli DH5α. The enzyme concentration revealed by ELISA varied from 78.13 to 94.35 ng/ml and the specific activity varied from 34.20 to 25.97 nmol/h/mg. Western blotting done after affinity chromatography purification showed a single band of approximately 40 kDa, which was recognized by an IgY polyclonal antibody that was developed against the specific peptide of the native protein. Our 100 ml-shake-flask assays allowed us to improve the enzyme activity seven fold, compared to the E. coli JM109/pUC13-hrIDS-Like system. Additionally, the results obtained in the present study were equal to those obtained with the Pichia pastoris GS1115/ pPIC-9-hrIDS-Like system (3 L bioreactor scale). The system used in this work (E. coli DH5α/pGEX-3X-hrIDS-Like) emerges as a strategy for improving protein expression and purification, aimed at recombinant protein chemical characterization, future laboratory assays for enzyme replacement therapy, and as new evidence of active putative sulfatase production in E. coli.

Optimized Transformation of Streptomyces sp. ATCC 39366 Producing Leptomycin by Electroporation: Yong-Qiang Fan , Hong-Jian Liu , Li Yan , Yu-Shi Luan , Hai-Meng Zhou , Jun-Mo Yang , Shang-Jun Yin , Yu-Long Wang; J. Microbiol. 2013;51(3):318-322. Published online April 26, 2013; DOI: https://doi.org/10.1007/s12275-013-2428-y

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Abstract: Streptomyces sp. ATCC 39366 produces leptomycin derivatives. Leptomycin B, a potent and specific inhibitor against the export of nuclear proteins, is the main product; however, the introduction of DNA into this strain is almost impossible, which has impeded its further use. We developed a Streptomyces sp. ATCC 39366 transformation protocol to introduce foreign DNA via electroporation. Various conditions were examined, including treatments of the cell wall with weakening agents, electroporation parameters, and DNA content. We found that only plasmid DNA isolated from a dam- ET12567 strain resulted in successful transformation. The mycelium growing in a yeast-peptone-dextrose medium supplemented with 1% glycine at 28°C on a rotary shaker (220 rpm) was more dispersed than those without supplementation and prone to electroporation. The maximum transformation efficiency of 8×102 CFU/μg plasmid DNA was obtained at a field strength of 13 kV/cm with a time constant of 13 ms (25-μF capacitor; parallel resistance, 600 Ω) using 1-mm electrocuvettes. The results of the transformations of two other Streptomyces species indicated that the optimized conditions established in this study might only be applicable to Streptomyces sp. ATCC 39366. However, this is the first report of successful transformation of Streptomyces sp. ATCC 39366, and will facilitate the construction of a gene knockout mutant in Streptomyces sp. ATCC 39366 to produce series of new leptomycin derivatives.

Development of SCAR Primers Based on a Repetitive DNA Fingerprint for Escherichia coli Detection: Aphidech Sangdee , Sitakan Natphosuk , Adunwit Srisathan , Kusavadee Sangdee; J. Microbiol. 2013;51(1):31-35. Published online March 2, 2013; DOI: https://doi.org/10.1007/s12275-013-2244-4

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Abstract: The present study aimed to use enterobacterial repetitive intergenic consensus (ERIC) fingerprints to design SCAR primers for the detection of Escherichia coli. The E. coli strains were isolated from various water sources. The primary presumptive identification of E. coli was achieved using MacConkey agar. Nineteen isolates were selected and confirmed to be E. coli strains based on seven biochemical characteristics. ERIC-PCR with ERIC 1R and ERIC 2 primers were used to generate DNA fingerprints. ERIC-PCR DNA profiles showed variant DNA profiles among the tested E. coli strains and distinguished all E. coli strains from the other tested bacterial strains. A 350 bp band that predominated in five E. coli strains was used for the development of the species-specific SCAR primers EC-F1 and EC-R1. The primers showed good specificity for E. coli, with the exception of a single false positive reaction with Sh. flexneri DMST 4423. The primers were able to detect 50 pg and 100 CFU/ml of genomic DNA and cells of E. coli, respectively.

Genome-Wide Enrichment Screening Reveals Multiple Targets and Resistance Genes for Triclosan in Escherichia coli: Byung Jo Yu , Jung Ae Kim , Hyun Mok Ju , Soo-Kyung Choi , Seung Jin Hwang , Sungyoo Park , EuiJoong Kim , Jae-Gu Pan; J. Microbiol. 2012;50(5):785-791. Published online November 4, 2012; DOI: https://doi.org/10.1007/s12275-012-2439-0

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Abstract: Triclosan is a widely used biocide effective against different microorganisms. At bactericidal concentrations, triclosan appears to affect multiple targets, while at bacteriostatic concentrations, triclosan targets FabI. The site-specific antibioticlike mode-of-action and a widespread use of triclosan in household products claimed to possibly induce cross-resistance to other antibiotics. Thus, we set out to define more systematically the genes conferring resistance to triclosan; A genomic library of Escherichia coli strain W3110 was constructed and enriched in a selective medium containing a lethal concentration of triclosan. The genes enabling growth in the presence of triclosan were identified by using a DNA microarray and confirmed consequently by ASKA clones overexpressing the selected 62 candidate genes. Among these, forty-seven genes were further confirmed to enhance the resistance to triclosan; these genes, including the FabI target, were involved in inner or outer membrane synthesis, cellsurface material synthesis, transcriptional activation, sugar phosphotransferase (PTS) systems, various transporter systems, cell division, and ATPase and reductase/dehydrogenase reactions. In particular, overexpression of pgsA, rcsA, or gapC conferred to E. coli cells a similar level of triclosan resistance induced by fabI overexpression. These results indicate that triclosan may have multiple targets other than well-known FabI and that there are several undefined novel mechanisms for the resistance development to triclosan, thus probably inducing cross antibiotic resistance.

NOTE] Biosynthetic Pathway for Poly(3-Hydroxypropionate) in Recombinant Escherichia coli: Qi Wang , Changshui Liu , Mo Xian , Yongguang Zhang , Guang Zhao; J. Microbiol. 2012;50(4):693-697. Published online August 25, 2012; DOI: https://doi.org/10.1007/s12275-012-2234-y

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Abstract: Poly(3-hydroxypropionate) (P3HP) is a biodegradable and biocompatible thermoplastic. In this study, we engineered a P3HP biosynthetic pathway in recombinant Escherichia coli. The genes for malonyl-CoA reductase (mcr, from Chloroflexus aurantiacus), propionyl-CoA synthetase (prpE, from E. coli), and polyhydroxyalkanoate synthase (phaC1, from Ralstonia eutropha) were cloned and expressed in E. coli. The E. coli genes accABCD encoding acetyl-CoA carboxylase were used to channel the carbon into the P3HP pathway. Using glucose as a sole carbon source, the cell yield and P3HP content were 1.32 g/L and 0.98% (wt/wt [cell dry weight]), respectively. Although the yield is relatively low, our study shows the feasibility of engineering a P3HP biosynthetic pathway using a structurally unrelated carbon source in bacteria.

Bacteria-Based In Vivo Peptide Library Screening Using Biopanning Approach: Ji-Hyeon Choi , Sang-Hyun Park; J. Microbiol. 2011;49(5):847-851. Published online November 9, 2011; DOI: https://doi.org/10.1007/s12275-011-1405-6

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Abstract: Traditionally, library screening has been performed to identify biologically active agents including small molecules or peptides that inhibit target proteins or molecules with therapeutic interests. Due to its chemical nature, library screening is usually performed under in vitro environments using purified proteins and molecules. However, active agents identified from in vitro screenings often fail to exhibit biological activities in cells. To overcome this inherent limitation, we have developed an in vivo peptide library screening system that allows for the identification of dissociative inhibitors of protein interactions of interest. The screening is based on the reconstitution of the cI repressor from bacteriophage lambda with high-density expression peptide library and is entirely performed in bacteria cells. Furthermore, to enhance the efficacy and sensitivity of the screening, a multiple-round biopanning approach was employed for amplification and enrichment of positive peptides. Overall, this in vivo screening should provide a fast and efficient tool for identification of biologically active peptide molecules against target protein assembly.

Epidemiological Investigation of eaeA-Positive Escherichia coli and Escherichia albertii Strains Isolated from Healthy Wild Birds: Jae-Young Oh , Min-Su Kang , Hee-Tae Hwang , Byung-Ki An , Jun-Hun Kwon , Yong-Kuk Kwon; J. Microbiol. 2011;49(5):747-752. Published online November 9, 2011; DOI: https://doi.org/10.1007/s12275-011-1133-y

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Abstract: Escherichia coli has commonly been associated with diarrheal illness in humans and animals. Recently, E. albertii has been reported to be a potential pathogen of humans and animals and to be carried by wild birds. In the present study, the prevalence and genetic characteristics of intimin-producing E. coli and E. albertii strains were evaluated in wild birds in Korea. Thirty one of 790 Enterobacteriaceae strains from healthy wild birds were positive for the intimin gene (eaeA) and twenty two of the 31 strains were identified as atypical enteropathogenic E. coli (aEPEC) that did not possess both EAF and bfpA genes. A total of nine lactose non-fermenting coliform bacterial strains were identified as E. albertii by PCR and sequence analysis of housekeeping genes. A total of 28 (90.3%) eaeA-positive strains were isolated from waterfowl. Fifteen aEPEC (68.2%) and two E. albertii (22.2%) strains had a β-intimin subtype and 14 aEPEC strains harboring β-intimin belonged to phylogenetic group B2. All eaeA-positive E. albertii and 3 aEPEC strains possessed the cytolethal distending toxin gene (cdtB). The eaeA-positive E. coli and E. albertii strains isolated from healthy wild birds need to be recognized as a potential pathogroup that may pose a potential threat to human and animal health. These findings indicate that eaeA-positive E. coli as well as E. albertii can be carried by wild birds, posing a potential threat to human and animal health.

NOTE] Development of a High-Throughput Screening Method for Recombinant Escherichia coli with Intracellular Dextransucrase Activity: So-Ra Lee , Ah-Rum Yi , Hong-Gyun Lee , Myoung-Uoon Jang , Jung-Mi Park , Nam Soo Han , Tae-Jip Kim; J. Microbiol. 2011;49(2):320-323. Published online May 3, 2011; DOI: https://doi.org/10.1007/s12275-011-1078-1

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Abstract: To efficiently engineer intracellular dextransucrase (DSase) expression in Escherichia coli, a high-throughput screening method was developed based on the polymer-forming activity of the enzyme. Recombinant E. coli containing the Leuconostoc citreum DSase (LcDS) gene was grown on Luria-Bertani agar plates, containing 2% sucrose, at 37°C for 8 h. The plates were then evenly overlaid with 0.6% soft agar, containing 1.2 mg/ml D-cycloserine, and incubated at 30°C to allow gradual cell disruption until a dextran polymer grew through the overlaid layer. A significant correlation between dextran size and enzyme activity was established and applied for screening truncated mutants with LcDS activity.

Occurrence and Antimicrobial Drug Susceptibility Patterns of Commensal and Diarrheagenic Escherichia coli in Fecal Microbiota from Children with and without Acute Diarrhea: Patrícia G. Garcia , Vânia L. Silva , Cláudio G. Diniz; J. Microbiol. 2011;49(1):46-52. Published online March 3, 2011; DOI: https://doi.org/10.1007/s12275-011-0172-8

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Abstract: Acute diarrhea is a public health problem and an important cause of morbidity and mortality, especially in developing countries. The etiology is varied, and the diarrheagenic Escherichia coli pathotypes are among the most important. Our objectives were to determine the occurrence of commensal and diarrheagenic E. coli strains in fecal samples from children under five years old and their drug susceptibility patterns. E. coli were isolated from 141 fresh fecal samples; 84 were obtained from clinically injured donors with acute diarrhea (AD) and 57 from clinically healthy donors without diarrhea (WD). Presumptive phenotypic species identification was carried out and confirmed by amplification of specific 16S ribosomal RNA encoding DNA. Multiplex PCR was performed to characterize the diarrheagenic E. coli strains. Drug susceptibility patterns were determined by the disc-diffusion method. In total, 220 strains were recovered from the fecal specimens (61.8% from AD and 38.2% from WD). Diarrheagenic E. coli was identified at a rate of 36.8% (n=50) in diarrheic feces and 29.8% (n=25) in non-diarrheic feces. Enteroaggregative E. coli was the most frequently identified pathotype in the AD group (16.2%) and the only pathotype identified in the WD group (30.9%). Enteropathogenic E. coli was the second most isolated pathotype (10.3%), followed by Shiga toxin-producing E. coli (7.4%) and enterotoxigenic E. coli (2.9%). No enteroinvasive E. coli strains were recovered. The isolates showed high resistance rates against ampicillin, tetracycline, and sulfamethoxazole-trimethoprim. The most effective drugs were ceftazidime, ceftriaxone, imipenem and piperacillin-tazobactam, for which no resistance was observed. Differentiation between the diarrheagenic E. coli pathotypes is of great importance since they are involved in acute diarrheal diseases and may require specific antimicrobial chemotherapy. The high antimicrobial resistance observed in our study raises a broad discussion on the indiscriminate or improper use of antimicrobials, besides the risks of self-medication.

Multilocus Sequence Typing and Virulence Factors Analysis of Escherichia coli O157 Strains in China: Xiao W. Ji , Ya L. Liao , Ye F. Zhu , Hai G. Wang , Ling Gu , Jiang Gu , Chen Dong , Hong L. Ding , Xu H. Mao , Feng C. Zhu , Quan M. Zou; J. Microbiol. 2010;48(6):849-855. Published online January 9, 2011; DOI: https://doi.org/10.1007/s12275-010-0132-8

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Abstract: Escherichia coli O157:H7, an important food-borne pathogen, has become a major public health concern worldwide. The aim of this study was to investigate the molecular epidemiologic feature of E. coli O157:H7 strains in China. 105 E. coli O157:H7 isolates were collected from various hosts and places over 9 years. A multilocus sequence typing scheme (MLST) was applied for bacteria genotyping and polymerase chain reaction (PCR) was used for virulence factor identification. Seven new MLST sequence types (STs), namely ST836, ST837, ST838, ST839, ST840, ST841, and ST842 were identified, which grouped into two lineages. Phylogenetic analysis suggested that the most two frequent STs in China, ST837 and ST836, may be the derivatives of E. coli O157:H7 Sakai or E. coli O157:H7 EDL933. Geographical diversity and host variety of E. coli O157:H7 were observed in China. In addition, the different distribution of tccp was detected. The data presented herein provide new insights into the molecular epidemiologic feature of E. coli O157:H7, and aid in the investigation of the transmission regularity and evolutionary mechanism of E. coli O157:H7.

Characterization of Escherichia coli EutD: a Phosphotransacetylase of the Ethanolamine Operon: Federico P. Bologna , Valeria A. Campos-Bermudez , Damián D. Saavedra , Carlos S. Andreo , María F. Drincovich; J. Microbiol. 2010;48(5):629-636. Published online November 3, 2010; DOI: https://doi.org/10.1007/s12275-010-0091-0

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Abstract: The Escherichia coli genes pta and eutD encode proteins containing the phosphate-acetyltransferase domain. EutD is composed only by this domain and belongs to the ethanolamine operon. This enzyme has not been characterized yet, and its relationship to the multimodular E. coli phosphotransacetylase (Pta) remains unclear. In the present work, a detailed characterization of EutD from E. coli (EcEutD) was performed. The enzyme is a more efficient phosphotransacetylase than E. coli Pta (EcPta) in catalyzing its reaction in either direction and assembles as a dimer, being differentially modulated by EcPta effectors. When comparing EutD and Pta, both from E. coli, certain divergent regions of the primary structure responsible for their unique properties can be found. The growth on acetate of the E. coli pta acs double-mutant strain, was complemented by either introducing EcEutD or by inducing the eut operon with ethanolamine. In this case, the expression of a phosphotransacetylase different from Pta was confirmed by activity assays. Overall, the results indicate that EcEutD and Pta, although able to catalyse the same reaction, display differential efficiency and regulation, and also differ in the induction of their expression. However, under certain growth conditions, they can fulfil equal roles in E. coli metabolism.

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