The properties of 5-methyltetrahydrofolate dehydrogenase (MthfD) and its role in the tetrahydrofolate (THF)-dependent dicamba demethylation system inRhizorhabdus dicambivoransNdbn-20

2019 ◽  
Author(s):  
Shigang Yao ◽  
Le Chen ◽  
Zhou Yang ◽  
Li Yao ◽  
Jianchun Zhu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Dehydrogenase Activity ◽  
Gene Disruption ◽  
Reductase Activity ◽  
Regeneration Pathway

ABSTRACTThe herbicide dicamba is initially degrade via demethylation inRhizorhabdus dicambivoransNdbn-20. A gene cluster scaffold 66 containing a THF-dependent dicamba methyltransferasedmtand three THF metabolic-related genes, namely,mthfD,dhcandpurU, is responsible for dicamba demethylation in this strain. However, the characteristics and functions of MthfD, Dhc and PurU have not been elucidated. In this study, MthfD was synthesized inEscherichia coliBL21(DE3) and purified as a His6-tagged protein. Purified MthfD was found to be a monomer, and exhibited 5-CH3-THF dehydrogenase activityin vitro. TheKcatandKmfor 5-CH3-THF were 0.23 s−1and 16.48 μM, respectively. However, 5,10-CH2-THF reductase activity was not detected for MthfD yet. Gene disruption results showed thatmthfDis essential for dicamba degradation, whereasdhcis dispensable. Our studies revealed that MthfD physiologically is a 5-CH3-THF dehydrogenase that catalyzes the irreversible dehydrogenation of 5-CH3-THF to 5,10-CH2-THF in the THF regeneration pathway during dicamba demethylation inR. dicambivoransNdbn-20.

scholarly journals SlyA and H-NS Regulate Transcription of the Escherichia coli K5 Capsule Gene Cluster, and Expression of slyA in Escherichia coli Is Temperature-dependent, Positively Autoregulated, and Independent of H-NS

2007 ◽  
Vol 282 (46) ◽  
pp. 33326-33335 ◽  
Author(s):  
David Corbett ◽  
Hayley J. Bennett ◽  
Hamdia Askar ◽  
Jeffrey Green ◽  
Ian S. Roberts
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Regulation Of Transcription ◽  
Temperature Dependent ◽  
Mobility Shift ◽  
E Coli ◽  
Dnase I Footprinting ◽  
Nucleoprotein Complex ◽  
Electrophoretic Mobility Shift Assays

In this paper, we present the first evidence of a role for the transcriptional regulator SlyA in the regulation of transcription of the Escherichia coli K5 capsule gene cluster and demonstrate, using a combination of reporter gene fusions, DNase I footprinting, and electrophoretic mobility shift assays, the dependence of transcription on the functional interplay between H-NS and SlyA. Both SlyA and H-NS bind to multiple overlapping sites within the promoter in vitro, but their binding is not mutually exclusive, resulting in a remodeled nucleoprotein complex. In addition, we show that expression of the E. coli slyA gene is temperature-regulated, positively autoregulated, and independent of H-NS.

Bacteriophage Mu-mediated gene transposition and in vitro cloning of the enterochelin gene cluster of Escherichia coli

Gene ◽  
1980 ◽  
Vol 11 (3-4) ◽  
pp. 347-357 ◽  
Author(s):  
Alan J. Laird ◽  
Douglas W. Ribbons ◽  
Graeme C. Woodrow ◽  
Ian G. Young
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Bacteriophage Mu ◽  
Gene Transposition

scholarly journals Genotyping of a gene cluster for production of colibactin and in vitro genotoxicity analysis of Escherichia coli strains obtained from the Japan Collection of Microorganisms

2020 ◽  
Vol 42 (1) ◽  
Author(s):  
Masanobu Kawanishi ◽  
Chiaki Shimohara ◽  
Yoshimitsu Oda ◽  
Yuuta Hisatomi ◽  
Yuta Tsunematsu ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
In Vitro Genotoxicity

EFFECTS OF TAMOXIFEN ON THE BINDING AND METABOLISM OF TESTOSTERONE BY HUMAN PROSTATIC TISSUE AND PLASMA IN VITRO

1979 ◽  
Vol 83 (3) ◽  
pp. 369-378 ◽  
Author(s):  
F. K. HABIB ◽  
G. RAFATI ◽  
M. R. G. ROBINSON ◽  
S. R. STITCH
Keyword(s):  
Dehydrogenase Activity ◽  
Reductase Activity ◽  
Hydroxysteroid Dehydrogenase ◽  
Inhibitory Effect ◽  
Prostatic Tissue ◽  
Sex Hormone Binding Globulin ◽  
Benign Tissue ◽  
The Mean ◽  
Malignant Prostate

The in-vitro metabolism of testosterone in benign and malignant prostatic tissue was examined and distinct quantitative differences between the two types of specimens were observed. The major metabolite of testosterone in the hyperplastic prostate was 5α-dihydrotestosterone and a high 3α(β)-hydroxysteroid dehydrogenase activity was also detected. In the malignant tissue, 5α-reductase activity was considerably reduced and there was little or no androstanediol formed; the 17β-dehydrogenase activity was, however, higher than in the benign tissue. The decrease in 5α-reductase was always followed by a compensatory change in the 3α(β)-hydroxysteroid dehydrogenase of the malignant prostate. The present study revealed that the ratio of the mean activities of 5α-reductase to 3α(β)-hydroxysteroid dehydrogenase in the two types of specimen always remained a constant. Although the antioestrogen, tamoxifen, induced an inhibitory effect on the activities of 5α-reductase and 17β-hydroxysteroid dehydrogenase in the gland, the present investigation also suggested that tamoxifen stimulated the activity of 3α(3β)-hydroxysteroid dehydrogenase. In blood, the action of tamoxifen appeared to be confined to the displacement of androgens from the binding sites on the sex hormone binding globulin.

scholarly journals Proteins Encoded by Sphingomonas elodea ATCC 31461 rmlA and ugpG Genes, Involved in Gellan Gum Biosynthesis, Exhibit both dTDP- and UDP-Glucose Pyrophosphorylase Activities

2005 ◽  
Vol 71 (8) ◽  
pp. 4703-4712 ◽  
Author(s):  
Elisabete Silva ◽  
Ana Rita Marques ◽  
Arsénio Mendes Fialho ◽  
Ana Teresa Granja ◽  
Isabel Sá-Correia
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Biochemical Characterization ◽  
Sequence Similarity ◽  
Gelling Agent ◽  
Phosphate Binding ◽  
Sphingomonas Elodea ◽  
Gene Maps

ABSTRACT The commercial gelling agent gellan is a heteropolysaccharide produced by Sphingomonas elodea ATCC 31461. In this work, we carried out the biochemical characterization of the enzyme encoded by the first gene (rmlA) of the rml 4-gene cluster present in the 18-gene cluster required for gellan biosynthesis (gel cluster). Based on sequence homology, the putative rml operon is presumably involved in the biosynthesis of dTDP-rhamnose, the sugar necessary for the incorporation of rhamnose in the gellan repeating unit. Heterologous RmlA was purified as a fused His6-RmlA protein from extracts prepared from Escherichia coli IPTG (isopropyl-β-d-thiogalactopyranoside)-induced cells, and the protein was proven to exhibit dTDP-glucose pyrophosphorylase (Km of 12.0 μM for dTDP-glucose) and UDP-glucose pyrophosphorylase (Km of 229.0 μM for UDP-glucose) activities in vitro. The N-terminal region of RmlA exhibits the motif G-X-G-T-R-X2-P-X-T, which is highly conserved among bacterial XDP-sugar pyrophosphorylases. The motif E-E-K-P, with the conserved lysine residue (K163) predicted to be essential for glucose-1-phosphate binding, was observed. The S. elodea ATCC 31461 UgpG protein, encoded by the ugpG gene which maps outside the gel cluster, was previously identified as the UDP-glucose pyrophosphorylase involved in the formation of UDP-glucose, also required for gellan synthesis. In this study, we demonstrate that UgpG also exhibits dTDP-glucose pyrophosphorylase activity in vitro and compare the kinetic parameters of the two proteins for both substrates. DNA sequencing of ugpG gene-adjacent regions and sequence similarity studies suggest that this gene maps with others involved in the formation of sugar nucleotides presumably required for the biosynthesis of another cell polysaccharide(s).

scholarly journals Analysis of the Mycosamine Biosynthesis and Attachment Genes in the Nystatin Biosynthetic Gene Cluster of Streptomyces noursei ATCC 11455

2007 ◽  
Vol 73 (22) ◽  
pp. 7400-7407 ◽  
Author(s):  
Aina Nedal ◽  
Håvard Sletta ◽  
Trygve Brautaset ◽  
Sven E. F. Borgos ◽  
Olga N. Sekurova ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biological Activity ◽  
Gene Cluster ◽  
Macrolide Antibiotic ◽  
Biosynthetic Gene Cluster ◽  
Biosynthetic Gene ◽  
Polyene Macrolide Antibiotic ◽  
Streptomyces Noursei ◽  
Dehydratase Activity

ABSTRACT The polyene macrolide antibiotic nystatin produced by Streptomyces noursei contains a deoxyaminosugar mycosamine moiety attached to the C-19 carbon of the macrolactone ring through the β-glycosidic bond. The nystatin biosynthetic gene cluster contains three genes, nysDI, nysDII, and nysDIII, encoding enzymes with presumed roles in mycosamine biosynthesis and attachment as glycosyltransferase, aminotransferase, and GDP-mannose dehydratase, respectively. In the present study, the functions of these three genes were analyzed. The recombinant NysDIII protein was expressed in Escherichia coli and purified, and its in vitro GDP-mannose dehydratase activity was demonstrated. The nysDI and nysDII genes were inactivated individually in S. noursei, and analyses of the resulting mutants showed that both genes produced nystatinolide and 10-deoxynystatinolide as major products. Expression of the nysDI and nysDII genes in trans in the respective mutants partially restored nystatin biosynthesis in both cases, supporting the predicted roles of these two genes in mycosamine biosynthesis and attachment. Both antifungal and hemolytic activities of the purified nystatinolides were shown to be strongly reduced compared to those of nystatin, confirming the importance of the mycosamine moiety for the biological activity of nystatin.

scholarly journals Sulfation and amidinohydrolysis in the biosynthesis of giant linear polyenes

2017 ◽  
Vol 13 ◽  
pp. 2408-2415 ◽  
Author(s):  
Hui Hong ◽  
Markiyan Samborskyy ◽  
Katsiaryna Usachova ◽  
Katharina Schnatz ◽  
Peter F Leadlay
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Late Stage ◽  
Rare Case ◽  
Gene Clusters ◽  
Biosynthetic Gene ◽  
Starter Unit ◽  
Linear Polyenes ◽  
Streptomyces Malaysiensis

Clethramycin from Streptomyces malaysiensis DSM4137, and mediomycins (produced together with clethramycin from Streptomyces mediocidicus), are near-identical giant linear polyenes apparently constructed from, respectively, a 4-guanidinobutanoate or 4-aminobutanoate starter unit and 27 polyketide extender units, and bearing a specific O-sulfonate modification at the C-29 hydroxy group. We show here that mediomycins are actually biosynthesised not by use of a different starter unit but by direct late-stage deamidination of (desulfo)clethramycin. A gene (slf) encoding a candidate sulfotransferase has been located in both gene clusters. Deletion of this gene in DSM4137 led to accumulation of desulfoclethramycin only, instead of a mixture of desulfoclethramycin and clethramycin. The mediomycin gene cluster does not encode an amidinohydrolase, but when three candidate amidinohydrolase genes from elsewhere in the S. mediocidicus genome were individually expressed in Escherichia coli and assayed, only one of them (medi4948), located 670 kbp away from the mediomycin gene cluster on the chromosome, catalysed the removal of the amidino group from desulfoclethramycin. Subsequent cloning of medi4948 into DSM4137 caused mediomycins A and B to accumulate at the expense of clethramycin and desulfoclethramycin, respectively, a rare case where an essential biosynthetic gene is not co-located with other pathway genes. Clearly, both desulfoclethramycin and clethramycin are substrates for this amidinohydrolase. Also, purified recombinant sulfotransferase from DSM4137, in the presence of 3'-phosphoadenosine-5'-phosphosulfate as donor, efficiently converted mediomycin B to mediomycin A in vitro. Thus, in the final steps of mediomycin A biosynthesis deamidination and sulfotransfer can take place in either order.

ucFabV Requires Functional Reductase Activity to Confer Reduced Triclosan Susceptibility in Escherichia coli

2015 ◽  
Vol 25 (6) ◽  
pp. 394-402 ◽  
Author(s):  
Taylor L. Fischer ◽  
Robert J. White ◽  
Katherine F.K. Mares ◽  
Devin E. Molnau ◽  
Justin J. Donato
Keyword(s):  
Escherichia Coli ◽  
Reductase Activity ◽  
Acid Synthesis ◽  
Temperature Sensitive ◽  
Wild Type ◽  
E Coli ◽  
Enoyl Acp Reductase ◽  
Selection For

<b><i>Background/Aims:</i></b> We previously identified the Triclo1 fosmid in a functional metagenomic selection for clones that increased triclosan tolerance in <i>Escherichia coli</i>. The active enzyme encoded by Triclo1 is ucFabV. Although ucFabV is homologous to FabV from other organisms, ucFabV contains substitutions at key positions that would predict differences in substrate binding. Therefore, a detailed characterization of ucFabV was conducted to link its biochemical activity to its ability to confer reduced triclosan sensitivity. <b><i>Methods:</i></b> ucFabV and a catalytic mutant were purified and used to reduce crotonoyl-CoA in vitro. The mutant and wild-type enzymes were introduced into <i>E. coli</i>, and their ability to confer triclosan tolerance as well as suppress a temperature-sensitive mutant of FabI were measured. <b><i>Results:</i></b> Purified ucFabV, but not the mutant, reduced crotonoyl-CoA in vitro. The wild-type enzyme confers increased triclosan tolerance when introduced into <i>E. coli</i>, whereas the mutant remained susceptible to triclosan<i>. </i>Additionally, wild-type ucFabV, but not the mutant, functionally replaced FabI within living cells. <b><i>Conclusion:</i></b> ucFabV confers increased tolerance through its function as an enoyl-ACP reductase. Furthermore, ucFabV is capable of restoring viability in the presence of compromised FabI, suggesting ucFabV is likely facilitating an alternate step within fatty acid synthesis, bypassing FabI inhibition.

scholarly journals Characterization of Stg Fimbriae from an Avian Pathogenic Escherichia coli O78:K80 Strain and Assessment of Their Contribution to Colonization of the Chicken Respiratory Tract

2006 ◽  
Vol 188 (18) ◽  
pp. 6449-6459 ◽  
Author(s):  
Maria H. Lymberopoulos ◽  
Sébastien Houle ◽  
France Daigle ◽  
Simon Léveillé ◽  
Annie Brée ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Gene Cluster ◽  
Distinct Group ◽  
Immunogold Electron Microscopy ◽  
Carbohydrate Source ◽  
E Coli ◽  
Tract Infections ◽  
K 12

ABSTRACT In a previous study, ecs-3, a sequence from avian pathogenic Escherichia coli (APEC) O78:K80 strain χ7122, was found to be expressed in vivo in infected chicken tissues. The region encompassing ecs-3 carries a fimbrial gene cluster that is a putative ortholog of the stg fimbrial gene cluster of Salmonella enterica serovar Typhi. This APEC fimbrial gene cluster, which we have termed stg, is a member of a distinct group of related fimbriae that are located in the glmS-pstS intergenic region of certain E. coli and S. enterica strains. Under the control of the pBAD promoter, the production of Stg fimbriae was demonstrated by Western blotting and immunogold electron microscopy with E. coli K-12. Transcriptional fusions suggest that stg expression is influenced by the carbohydrate source and decreased by the addition of iron and that Fur plays a role in the regulation of stg expression. stg sequences were associated with APEC O78 isolates, and stg was phylogenetically distributed among E. coli reference strains and clinical isolates from human urinary tract infections. Stg fimbriae contributed to the adherence of a nonfimbriated E. coli K-12 strain to avian lung sections and human epithelial cells in vitro. Coinfection experiments with APEC strain χ7122 and an isogenic Δstg mutant demonstrated that compared to the wild-type parent, the Δstg mutant was less able to colonize air sacs, equally able to colonize lungs, and able to more effectively colonize tracheas of infected chickens. Stg fimbriae, together with other adhesins, may therefore contribute to the colonization of avian respiratory tissues by certain APEC strains.

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