scholarly journals Orotate Phosphoribosyltransferase from Corynebacterium ammoniagenes Lacking a Conserved Lysine

2007 ◽  
Vol 189 (24) ◽  
pp. 9030-9036 ◽  
Author(s):  
Xing Wang ◽  
Cuiqing Ma ◽  
Xiuwen Wang ◽  
Ping Xu
Keyword(s):  
Escherichia Coli ◽  
Molecular Mass ◽  
Active Sites ◽  
Transfer Reaction ◽  
Gel Filtration ◽  
Orotate Phosphoribosyltransferase ◽  
Gene Encoding ◽  
Corynebacterium Ammoniagenes ◽  
Serovar Typhimurium ◽  
Optimal Ph

ABSTRACT The pyrE gene, encoding orotate phosphoribosyltransferase (OPRTase), was cloned by nested PCR and colony blotting from Corynebacterium ammoniagenes ATCC 6872, which is widely used in nucleotide production. Sequence analysis shows that there is a lack of an important conserved lysine (Lys 73 in Salmonella enterica serovar Typhimurium OPRTase) in the C. ammoniagenes OPRTase. This lysine has been considered to contribute to the initiation of catalysis. The enzyme was overexpressed and purified from a recombinant Escherichia coli strain. The molecular mass of the purified OPRTase was determined to be 45.4 ± 1.5 kDa by gel filtration. Since the molecular mass for the subunit of the enzyme was 21.3 ± 0.6 kDa, the native enzyme exists as a dimer. Divalent magnesium was necessary for the activity of the enzyme and can be substituted for by Mn2+ and Co2+. The optimal pH for the forward (phosphoribosyl transfer) reaction is 10.5 to 11.5, which is higher than that of other reported OPRTases, and the optimal pH for the reverse (pyrophosphorolysis) reaction is 5.5 to 6.5. The K m values for the four substrates were determined to be 33 μM for orotate, 64 μM for 5-phosphoribosyl-1-pyrophosphate (PRPP), 45 μM for orotidine-5-phosphate (OMP), and 36 μM for pyrophosphate. The K m value for OMP is much larger than those of other organisms. These differences may be due to the absence of Lys 73, which is present in the active sites of other OPRTases and is known to interact with OMP and PRPP.

scholarly journals Steric Gate Variants of UmuC Confer UV Hypersensitivity on Escherichia coli

2008 ◽  
Vol 191 (15) ◽  
pp. 4815-4823 ◽  
Author(s):  
Brenna W. Shurtleff ◽  
Jaylene N. Ollivierre ◽  
Mohammad Tehrani ◽  
Graham C. Walker ◽  
Penny J. Beuning
Keyword(s):  
Escherichia Coli ◽  
Active Sites ◽  
Uv Light ◽  
Dna Polymerases ◽  
Dna Lesions ◽  
Dominant Negative ◽  
Gene Encoding ◽  
Futile Cycle ◽  
Y Family ◽  
Negative Phenotype

ABSTRACT Y family DNA polymerases are specialized for replication of damaged DNA and represent a major contribution to cellular resistance to DNA lesions. Although the Y family polymerase active sites have fewer contacts with their DNA substrates than replicative DNA polymerases, Y family polymerases appear to exhibit specificity for certain lesions. Thus, mutation of the steric gate residue of Escherichia coli DinB resulted in the specific loss of lesion bypass activity. We constructed variants of E. coli UmuC with mutations of the steric gate residue Y11 and of residue F10 and determined that strains harboring these variants are hypersensitive to UV light. Moreover, these UmuC variants are dominant negative with respect to sensitivity to UV light. The UV hypersensitivity and the dominant negative phenotype are partially suppressed by additional mutations in the known motifs in UmuC responsible for binding to the β processivity clamp, suggesting that the UmuC steric gate variant exerts its effects via access to the replication fork. Strains expressing the UmuC Y11A variant also exhibit decreased UV mutagenesis. Strikingly, disruption of the dnaQ gene encoding the replicative DNA polymerase proofreading subunit suppressed the dominant negative phenotype of a UmuC steric gate variant. This could be due to a recruitment function of the proofreading subunit or involvement of the proofreading subunit in a futile cycle of base insertion/excision with the UmuC steric gate variant.

Construction of a Novel Recombinant Escherichia coli Strain Capable of Producing 1,3–propanediol

2011 ◽  
Vol 396-398 ◽  
pp. 2499-2502 ◽  
Author(s):  
Xiang Hui Qi ◽  
Qi Guo ◽  
Yu Tuo Wei ◽  
Hong Xu ◽  
Ri Bo Huang
Keyword(s):  
Escherichia Coli ◽  
Specific Activity ◽  
Gel Filtration ◽  
Coli Strain ◽  
Optimal Temperature ◽  
Recombinant Enzymes ◽  
Microbial Conversion ◽  
Gene Encoding ◽  
E Coli ◽  
Nickel Chelate

1, 3-propanediol (1, 3-PD) is biologically synthesized by glycerol dehydratase (GDHt) and 1, 3-propanediol dehydrogenase (PDOR). In present study, the gldABC gene, encoding GDHt from Klebsiella pneumoniae and the yqhD gene, encoding PDOR isoenzyme from E.coli BL21 were cloned and co-expressed in E.coli JM109 using plasmid pSE380. The over-expressed recombinant enzymes were purified by nickel-chelate chromatography combined with gel filtration to study the properties. Optimal temperature and pH of recombinant GDHt with specific activity of 85.8 U/mg were 45 °C and 9.0; and optimal temperature and pH of recombinant YqhD with specific activity of 80.0 U/mg were 37 °C, 7.0. The microbial conversion of 1,3-PD from glycerol by this recombinant E. coli strain was studied and the production of 1,3-PD was about 28.0 g/l.

scholarly journals Purification, Characterization, and Sequence Analysis of 2-Aminomuconic 6-Semialdehyde Dehydrogenase from Pseudomonas pseudoalcaligenes JS45

1998 ◽  
Vol 180 (17) ◽  
pp. 4591-4595 ◽  
Author(s):  
Zhongqi He ◽  
John K. Davis ◽  
Jim C. Spain
Keyword(s):  
Molecular Mass ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Gel Filtration ◽  
Gene Encoding ◽  
Multiple Sequence ◽  
Pseudomonas Pseudoalcaligenes ◽  
Semialdehyde Dehydrogenase ◽  
Cell Extracts ◽  
High Degree

ABSTRACT 2-Aminonumconic 6-semialdehyde is an unstable intermediate in the biodegradation of nitrobenzene and 2-aminophenol by Pseudomonas pseudoalcaligenes JS45. Previous work has shown that enzymes in cell extracts convert 2-aminophenol to 2-aminomuconate in the presence of NAD+. In the present work, 2-aminomuconic semialdehyde dehydrogenase was purified and characterized. The purified enzyme migrates as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis with a molecular mass of 57 kDa. The molecular mass of the native enzyme was estimated to be 160 kDa by gel filtration chromatography. The optimal pH for the enzyme activity was 7.3. The enzyme is able to oxidize several aldehyde analogs, including 2-hydroxymuconic semialdehyde, hexaldehyde, and benzaldehyde. The gene encoding 2-aminomuconic semialdehyde dehydrogenase was identified by matching the deduced N-terminal amino acid sequence of the gene with the first 21 amino acids of the purified protein. Multiple sequence alignment of various semialdehyde dehydrogenase protein sequences indicates that 2-aminomuconic 6-semialdehyde dehydrogenase has a high degree of identity with 2-hydroxymuconic 6-semialdehyde dehydrogenases.

scholarly journals opdA, a Salmonella enterica Serovar Typhimurium Gene Encoding a Protease, Is Part of an Operon Regulated by Heat Shock

2000 ◽  
Vol 182 (2) ◽  
pp. 518-521 ◽  
Author(s):  
Christopher A. Conlin ◽  
Charles G. Miller
Keyword(s):  
Escherichia Coli ◽  
Heat Shock ◽  
Sigma Factor ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Temperature Shift ◽  
Open Reading Frame ◽  
Gene Encoding ◽  
Reading Frame ◽  
Serovar Typhimurium

ABSTRACT The opdA (prlC) gene of Salmonella enterica serovar Typhimurium and Escherichia coliencodes the metalloprotease oligopeptidase A (OpdA). We report thatopdA is cotranscribed with a downstream open reading frame,yhiQ. Transcription of this operon is induced after a temperature shift (30 to 42°C), and this induction depends on the heat shock sigma factor encoded by the rpoH(htpR) gene.

scholarly journals N-acetyl-d-neuraminic acid lyase generates the sialic acid for colominic acid biosynthesis in Escherichia coli K1

1996 ◽  
Vol 317 (1) ◽  
pp. 157-165 ◽  
Author(s):  
Miguel A. FERRERO ◽  
Angel REGLERO ◽  
Manuel FERNANDEZ-LOPEZ ◽  
Roberto ORDAS ◽  
Leandro B. RODRIGUEZ-APARICIO
Keyword(s):  
Escherichia Coli ◽  
Sialic Acid ◽  
Amino Acid ◽  
Molecular Mass ◽  
Gel Filtration ◽  
Neuraminic Acid ◽  
Acid Biosynthesis ◽  
Colominic Acid ◽  
Apparent Homogeneity ◽  
Escherichia Coli K1

Colominic acid is a capsular homopolymer from Escherichia coli K1 composed of α(2-8)-linked N-acetyl-d-neuraminic acid (NeuAc) residues. Recently, we have described that NeuAc synthesis in this bacterium occurs through the action of NeuAc lyase (EC 4.1.3.3) [Rodríguez-Aparicio, Ferrero and Reglero (1995) Biochem. J. 308, 501–505]. In the present work we analysed and characterized this enzyme. E. coli K1 NeuAc lyase is detected from the early logarithmic phase of growth, is induced by NeuAc and is not repressed by glucose. The enzyme was purified to apparent homogeneity (312-fold) using two types of hydrophobic chromatographies (butyl-agarose and phenyl-Sepharose CL-4B), gel filtration on Sephacryl S-200, and anion-exchange chromatography on DEAE-FPLC. The pure enzyme, whose amino acid composition and N-terminal amino acid sequence are also established, has a native molecular mass, estimated by gel filtration, of 135±3 kDa, whereas its molecular mass in SDS/PAGE was 33±1 kDa. The enzyme was able to synthesize and cleave NeuAc in a reversible reaction. The maximal rate of catalysis was achieved in 125 mM Tris/HCl buffer, pH 7.8, at 37 °C. Under these conditions, the Km values calculated for N-acetyl-d-mannosamine and pyruvate (condensation direction), and NeuAc (hydrolysis direction) were 7.7, 8.3 and 4.8 mM respectively. NeuAc synthesis by the pure enzyme was activated by Ca2+ and inhibited by Mn2+ and NeuAc, whereas the enzyme cleavage direction was inhibited by Ca2+, Mn2+ and pyruvate. The reaction products, NeuAc and pyruvate, and Ca2+ are able to regulate the direction of this enzyme (synthesis or cleavage of sialic acid) and, accordingly, to modulate colominic acid biosynthesis.

Gene cloning, protein purification, and enzymatic properties of multicopper oxidase, fromKlebsiellasp. 601

2008 ◽  
Vol 54 (9) ◽  
pp. 725-733 ◽  
Author(s):  
Yang Li ◽  
Jiao Yin ◽  
Guosheng Qu ◽  
Luchao Lv ◽  
Yadong Li ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Kinetic Studies ◽  
Multicopper Oxidase ◽  
Coli Strain ◽  
Gene Encoding ◽  
E Coli ◽  
C Terminus ◽  
Optimal Ph

A gene encoding a putative multicopper oxidase (MCO) was cloned from the soil bacterium Klebsiella sp. 601 and its corresponding enzyme was overexpressed in an Escherichia coli strain. Klebsiella sp. 601 MCO is composed of 536 amino acids with a molecular mass of 58.2 kDa. Theoretical calculation gave a pI value of 6.11. The amino acid sequence of Klebsiella sp. 601 MCO is strongly homologous to that of E. coli CueO with a similarity of 90% and an identity of 78%. Unlike E. coli CueO, Klebsiella sp. 601 MCO contains an extra 20 amino acids close to its C-terminus. The enzyme was purified to homogeneity by Ni-affinity chromatography. The purified enzyme was capable of using DMP (2,6-dimethoxyphenol), ABTS (2,2′-azino-bis(3-ethylbenzthiazolinesulfonic acid)), and SGZ (syringaldazine) as substrates with an optimal pH of 8.0 for DMP, 3.0 for ABTS, and 7.0 for SGZ. Klebsiella sp. 601 MCO was quite stable at pH 7.0 in which its activity was constant for 25 h without any significant change. Kinetic studies gave Km, kcat, and kcat/Kmvalues of 0.49 mmol·L–1, 1.08 × 103s–1, and 2.23 × 103s–1·mmol–1·L, respectively, for DMP, 5.63 mmol·L–1, 6.64 × 103s–1, and 1.18 × 103s–1·mmol–1·L for ABTS, and 0.023 mmol·L–1, 11 s–1, and 4.68 × 102s–1·mmol–1·L for SGZ.

scholarly journals Acquisition of the rfb-gnd Cluster in Evolution of Escherichia coli O55 and O157

2000 ◽  
Vol 182 (21) ◽  
pp. 6183-6191 ◽  
Author(s):  
Phillip I. Tarr ◽  
Laura M. Schoening ◽  
Yoo-Lee Yea ◽  
Teresa R. Ward ◽  
Srdjan Jelacic ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Salmonella Enterica ◽  
Side Chains ◽  
Gene Encoding ◽  
Gram Negative ◽  
E Coli ◽  
Phosphogluconate Dehydrogenase ◽  
Serovar Typhimurium ◽  
Polymorphic Gene ◽  
O Antigens

ABSTRACT The rfb region specifies the structure of lipopolysaccharide side chains that comprise the diverse gram-negative bacterial somatic (O) antigens. The rfb locus is adjacent to gnd, which is a polymorphic gene encoding 6-phosphogluconate dehydrogenase. To determine if rfb andgnd cotransfer, we sequenced gnd in five O55 and 13 O157 strains of Escherichia coli. E. coli O157:H7 has a gnd allele (allele A) that is only 82% identical to the gnd allele (alleleD) of closely related E. coli O55:H7. In contrast, gnd alleles of E. coli O55 in distant lineages are >99.9% identical to gnd alleleD. Though gnd alleles B andC in E. coli O157 that are distantly related toE. coli O157:H7 are more similar to allele Athan to allele D, there are nucleotide differences at 4 to 6% of their sites. Alleles B and C can be found in E. coli O157 in different lineages, but we have found allele A only in E. coli O157 belonging to the DEC5 lineage. DNA 3′ to the O55 gnd allele in diverse E. coli lineages has sequences homologous totnpA of the Salmonella enterica serovar Typhimurium IS200 element, E. coli Rhs elements (including an H-rpt gene), and portions of the O111 and O157rfb regions. We conclude that rfb andgnd cotransferred into E. coli O55 and O157 in widely separated lineages and that recombination was responsible for recent antigenic shifts in the emergence of pathogenic E. coli O55 and O157.

Separation of alkaline phosphatase isoenzymes from human kidney and comparison with alkaline phosphatases from other human tissues, urine, and Escherichia coli.

1983 ◽  
Vol 29 (1) ◽  
pp. 100-106 ◽  
Author(s):  
A W Hodson
Keyword(s):  
Escherichia Coli ◽  
Alkaline Phosphatase ◽  
Molecular Mass ◽  
Gel Filtration ◽  
Human Kidney ◽  
Human Tissues ◽  
Ammonium Sulfate Precipitation ◽  
Alkaline Phosphatases ◽  
Alkaline Phosphatase Isoenzymes ◽  
Starch Gel

Abstract Human kidney isoenzymes of alkaline phosphatase (EC 3.1.3.1) after extraction with butan-1-ol were separated by ammonium sulfate precipitation, gel filtration, and chromatofocusing fractionation methods. The separation at each fractionation step was monitored by starch gel and equilibrium-gradient-pore electrophoresis, the latter technique also being used to determine molecular mass. The determined molecular mass (daltons) of alkaline phosphatase from human placenta was 132 000, from urine 95 000, and three isoenzymes from kidney were 195 000, 140 000, and 95 000, respectively. The mass of Escherichia coli alkaline phosphatase was 80 000 daltons, and that of human liver alkaline phosphatase was assumed to be 160 000 daltons. The urinary isoenzyme and the electrophoretically fastest migrating kidney isoenzyme were similar with regard to pH optima, charge, and molecular mass as well as response to L-phenylalanine, L-homoarginine, heat, and urea. Bacterial alkaline phosphatase could be distinguished from the alkaline phosphatases in human tissues and urine by differences in the response to changes in pH and several other physicochemical properties.

Expression of full-length human alkylglycerol monooxygenase and fragments in Escherichia coli

Pteridines ◽  
2013 ◽  
Vol 24 (1) ◽  
pp. 111-115 ◽  
Author(s):  
Matthias Mayer ◽  
Markus A. Keller ◽  
Katrin Watschinger ◽  
Gabriele Werner-Felmayer ◽  
Ernst R. Werner ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Active Site ◽  
Active Sites ◽  
Gel Filtration ◽  
Full Length ◽  
Expression Vectors ◽  
Alkyl Ether ◽  
High Tendency ◽  
Hydrophobic Domain ◽  
E Coli

AbstractAlkylglycerol monooxygenase (AGMO; EC 1.14.16.5) is the only enzyme known to cleave the O-alkyl ether bond of alkylglycerols in humans. It is an integral membrane protein with nine predicted transmembrane domains. We attempted to express and purify full-length and truncated forms of AGMO in Escherichia coli. Full-length AGMO could not be expressed in three different E. coli expression strains, three different expression vectors and several induction systems. We succeeded, however, in expression of three N-terminally strep-tagged truncated forms, named active sites 1, 2 and 3, with 205, 134 and 61 amino acids, respectively. Active site 1 fragment, containing two predicted transmembrane regions, a membrane associated region and all known amino acid residues important for catalytic activity, was not fully soluble even in 8 M urea. Active site 2 containing only one predicted membrane associated domain required 8 M urea for solubilisation and eluted in gel filtration in 1 M urea as a trimer. Active site 3 with no hydrophobic domain eluted in gel filtration in 1 M urea as monomer and dimer. These results show that even truncated forms of AGMO are barely soluble when expressed in E. coli and show a high tendency for aggregation.

scholarly journals Properties of Leishmania major dUTP nucleotidohydrolase, a distinct nucleotide-hydrolysing enzyme in kinetoplastids

2000 ◽  
Vol 346 (1) ◽  
pp. 163-168 ◽  
Author(s):  
Ana CAMACHO ◽  
Fernando HIDALGO-ZARCO ◽  
Victor BERNIER-VILLAMOR ◽  
Luis M. RUIZ-PÉREZ ◽  
Dolores GONZÁLEZ-PACANOWSKA
Keyword(s):  
Escherichia Coli ◽  
Leishmania Major ◽  
Gel Filtration ◽  
Recombinant Enzyme ◽  
Limited Capacity ◽  
Reaction Products ◽  
Gene Encoding ◽  
Parasitic Protozoan ◽  
Phosphatase Inhibitor ◽  
Capacity To Act

We have previously reported the presence, in the parasitic protozoan Leishmania major, of an enzyme involved in controlling intracellular dUTP levels. The gene encoding this enzyme has now been overexpressed in Escherichia coli, and the recombinant enzyme was purified to homogeneity. Biochemical and enzymic analyses of the Leishmania enzyme show that it is a novel nucleotidohydrolase highly specific for deoxyuridine 5ʹ-triphosphate. The enzyme has proved to be a dimer by gel filtration and is able to hydrolyse both dUTP and dUDP quite efficiently, acting as a dUTP nucleotidohydrolase (dUTPase)-dUDP nucleotidohydrolase but has a limited capacity to act upon other nucleoside di- or triphosphates. The reaction products are dUMP and PPi when dUTP is the substrate and dUMP and Pi in the case of dUDP. The enzyme is sensitive to inhibition by the reaction product dUMP but not by PPi. dUTPase activity is highly dependent on Mg2+ concentrations and markedly sensitive to the phosphatase inhibitor, NaF. In summary, Leishmania dUTPase appears to be markedly different to other proteins characterized previously that accomplish the same function.

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