scholarly journals S-Methylmethionine Metabolism in Escherichia coli

1999 ◽  
Vol 181 (2) ◽  
pp. 662-665 ◽  
Author(s):  
Martin Thanbichler ◽  
Bernhard Neuhierl ◽  
August Böck
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Sequence Similarity ◽  
Physiological Role ◽  
High Sequence Similarity ◽  
Reading Frame ◽  
Amino Acid Permeases ◽  
Sequence Similarities ◽  
Homocysteine Methyltransferase

ABSTRACT Selenium-accumulating Astragalus spp. contain an enzyme which specifically transfers a methyl group fromS-methylmethionine to the selenol of selenocysteine, thus converting it to a nontoxic, since nonproteinogenic, amino acid. Analysis of the amino acid sequence of this enzyme revealed thatEscherichia coli possesses a protein (YagD) which shares high sequence similarity with the enzyme. The properties and physiological role of YagD were investigated. YagD is anS-methylmethionine: homocysteine methyltransferase which also accepts selenohomocysteine as a substrate. Mutants inyagD which also possess defects in metE andmetH are unable to utilize S-methylmethionine for growth, whereas a metE metH double mutant still grows on S-methylmethionine. Upstream of yagD and overlapping with its reading frame is a gene (ykfD) which, when inactivated, also blocks growth on methylmethionine in ametE metH genetic background. Since it displays sequence similarities with amino acid permeases it appears to be the transporter for S-methylmethionine. Methionine but notS-methylmethionine in the medium reduces the amount ofyagD protein. This and the existence of four MET box motifs upstream of yfkD indicate that the two genes are members of the methionine regulon. The physiological roles of the ykfDand yagD products appear to reside in the acquisition ofS-methylmethionine, which is an abundant plant product, and its utilization for methionine biosynthesis.

scholarly journals A Novel Highly Thermostable Multifunctional Beta-Glycosidase from CrenarchaeonAcidilobus saccharovorans

Archaea ◽  
2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Vadim M. Gumerov ◽  
Andrey L. Rakitin ◽  
Andrey V. Mardanov ◽  
Nikolai V. Ravin
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Half Life ◽  
Sequence Similarity ◽  
Hydrolytic Activity ◽  
Maximum Activity ◽  
Glycoside Hydrolases ◽  
Amino Acid Residues ◽  
High Tolerance ◽  
High Sequence Similarity

We expressed a putativeβ-galactosidase Asac_1390 from hyperthermophilic crenarchaeonAcidilobus saccharovoransinEscherichia coliand purified the recombinant enzyme. Asac_1390 is composed of 490 amino acid residues and showed high sequence similarity to family 1 glycoside hydrolases from various thermophilic Crenarchaeota. The maximum activity was observed at pH 6.0 and 93°C. The half-life of the enzyme at 90°C was about 7 hours. Asac_1390 displayed high tolerance to glucose and exhibits hydrolytic activity towards cellobiose and various aryl glucosides. The hydrolytic activity withp-nitrophenyl (pNP) substrates followed the order pNP-β-D-galactopyranoside (328 U mg−1), pNP-β-D-glucopyranoside (246 U mg−1), pNP-β-D-xylopyranoside (72 U mg−1), and pNP-β-D-mannopyranoside (28 U mg−1). Thus the enzyme was actually a multifunctionalβ-glycosidase. Therefore, the utilization of Asac_1390 may contribute to facilitating the efficient degradation of lignocellulosic biomass and help enhance bioconversion processes.

scholarly journals Topological Analysis of the Aerobic Membrane-Bound Formate Dehydrogenase of Escherichia coli

1998 ◽  
Vol 180 (24) ◽  
pp. 6625-6634 ◽  
Author(s):  
Stéphane Benoit ◽  
Hafid Abaibou ◽  
Marie-Andrée Mandrand-Berthelot
Keyword(s):  
Escherichia Coli ◽  
Formate Dehydrogenase ◽  
Sequence Similarity ◽  
Topological Analysis ◽  
Physiological Role ◽  
Respiratory Pathway ◽  
High Sequence Similarity ◽  
Entire Sequence ◽  
Membrane Bound ◽  
Lactamase Gene

ABSTRACT Besides formate dehydrogenase N (FDH-N), which is involved in the major anaerobic respiratory pathway in the presence of nitrate,Escherichia coli synthesizes a second isoenzyme, called FDH-O, whose physiological role is to ensure rapid adaptation during a shift from aerobiosis to anaerobiosis. FDH-O is a membrane-bound enzyme complex composed of three subunits, α (FdoG), β (FdoH), and γ (FdoI), which exhibit high sequence similarity to the equivalent polypeptides of FDH-N. The topology of these three subunits has been studied by using blaM (β-lactamase) gene fusions. A collection of 47 different randomly generated Fdo-BlaM fusions, 4 site-specific fusions, and 3 sandwich fusions were isolated along the entire sequence of the three subunits. In contrast to previously reported predictions from sequence analysis, our data suggested that the αβ catalytic dimer is located in the cytoplasm, with a C-terminal anchor for β protruding into the periplasm. As expected, the γ subunit, which specifies cytochrome b, was shown to cross the cytoplasmic membrane four times, with the N and C termini exposed to the cytoplasm. Protease digestion studies of the35S-labelled FDH-O heterotrimer in spheroplasts add further support to this model. Consistently, prior studies regarding the bioenergetic function of formate dehydrogenase provided evidence for a mechanism in which formate is oxidized in the cytoplasm.

scholarly journals A Major Secreted Elastase Is Essential for Pathogenicity of Aeromonas hydrophila

2000 ◽  
Vol 68 (6) ◽  
pp. 3233-3241 ◽  
Author(s):  
Alberto Cascón ◽  
Javier Yugueros ◽  
Alejandro Temprano ◽  
María Sánchez ◽  
Carmen Hernanz ◽  
...  
Keyword(s):  
Amino Acid ◽  
Aeromonas Hydrophila ◽  
Sequence Similarity ◽  
Opportunistic Pathogen ◽  
Aeromonas Salmonicida ◽  
Nucleotide Sequence Analysis ◽  
Gene Encoding ◽  
High Sequence Similarity ◽  
Reading Frame ◽  
Amino Acid Signal Peptide

ABSTRACT Aeromonas hydrophila is an opportunistic pathogen and the leading cause of fatal hemorrhagic septicemia in rainbow trout. A gene encoding an elastolytic activity, ahyB, was cloned from Aeromonas hydrophila AG2 into pUC18 and expressed inEscherichia coli and in the nonproteolytic speciesAeromonas salmonicida subsp. masoucida. Nucleotide sequence analysis of the ahyB gene revealed an open reading frame of 1,764 nucleotides with coding capacity for a 588-amino-acid protein with a molecular weight of 62,728. The first 13 N-terminal amino acids of the purified protease completely match those deduced from DNA sequence starting at AAG (Lys-184). This finding indicated that AhyB is synthesized as a preproprotein with a 19-amino-acid signal peptide, a 164-amino-acid N-terminal propeptide, and a 405-amino-acid intermediate which is further processed into a mature protease and a C-terminal propeptide. The protease hydrolyzed casein and elastin and showed a high sequence similarity to other metalloproteases, especially with the mature form of thePseudomonas aeruginosa elastase (52% identity),Helicobacter pylori zinc metalloprotease (61% identity), or proteases from several species of Vibrio (52 to 53% identity). The gene ahyB was insertionally inactivated, and the construct was used to create an isogenic ahyB mutant ofA. hydrophila. These first reports of a defined mutation in an extracellular protease of A. hydrophila demonstrate an important role in pathogenesis.

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.

Yeast regulatory gene GAL3: carbon regulation; UASGal elements in common with GAL1, GAL2, GAL7, GAL10, GAL80, and MEL1; encoded protein strikingly similar to yeast and Escherichia coli galactokinases

1988 ◽  
Vol 8 (8) ◽  
pp. 3439-3447 ◽  
Author(s):  
W Bajwa ◽  
T E Torchia ◽  
J E Hopper
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Regulatory Gene ◽  
Data Bank ◽  
Noncoding Region ◽  
Striking Similarity ◽  
Coding Region ◽  
Reading Frame ◽  
Carbon Regulation ◽  
Sequence Similarities

GAL3 gene expression is required for rapid GAL4-mediated galactose induction of the galactose-melibiose regulon genes in Saccharomyces cerevisiae. Here we show by Northern (RNA) blot analysis that GAL3 gene expression is itself galactose inducible. Like the GAL1, GAL7, GAL10, and MEL1 genes, the GAL3 gene is severely glucose repressed. Like the MEL1 gene, but in contrast to the GAL1, GAL7, and GAL10 genes, GAL3 is expressed at readily detectable basal levels in cells grown in noninducing, nonrepressing media. We determined the sequence of the S. cerevisiae GAL3 gene and its 5'-noncoding region. Within the 5'-noncoding region of the GAL3 gene, we found two sequences similar to the UASGal elements of the other galactose-melibiose regulon genes. Deletion analysis indicated that only the most ATG proximal of these sequences is required for GAL3 expression. The coding region of GAL3 consists of a 1,275-base-pair open reading frame in the direction of transcription. A comparison of the deduced 425-amino-acid sequence with the protein data bank revealed three regions of striking similarity between the GAL3 protein and the GAL1-specified galactokinase of Saccharomyces carlsbergensis. One of these regions also showed striking similarity to sequences within the galactokinase protein of Escherichia coli. On the basis of these protein sequence similarities, we propose that the GAL3 protein binds a molecule identical to or structurally related to one of the substrates or products of the galactokinase-catalyzed reaction.

scholarly journals Effects of Amino Acid Substitutions at Conserved and Acidic Residues within Region 1.1 of Escherichia coli ς70

2000 ◽  
Vol 182 (1) ◽  
pp. 221-224 ◽  
Author(s):  
Christina Wilson Bowers ◽  
Andrea McCracken ◽  
Alicia J. Dombroski
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Aspartic Acid ◽  
Transcription Initiation ◽  
Amino Acid Substitutions ◽  
Conserved Residues ◽  
Acidic Residues

ABSTRACT Amino acid substitutions in Escherichia coliς70 were generated and characterized in an analysis of the role of region 1.1 in transcription initiation. Several acidic and conserved residues are tolerant of substitution. However, replacement of aspartic acid 61 with alanine results in inactivity caused by structural and functional thermolability.

scholarly journals Novosphingobium gossypii sp. nov., isolated from Gossypium hirsutum

2015 ◽  
Vol 65 (Pt_9) ◽  
pp. 2831-2837 ◽  
Author(s):  
Peter Kämpfer ◽  
Karin Martin ◽  
John A. McInroy ◽  
Stefanie P. Glaeser
Keyword(s):  
Gossypium Hirsutum ◽  
Gene Sequence ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
High Sequence Similarity ◽  
Polar Lipid Profile ◽  
Gene Sequence Analysis ◽  
Bacterium Strain ◽  
Type Strains ◽  
Sequence Similarities

A Gram-stain-negative, rod-shaped, non-spore-forming bacterium (strain JM-1396T) producing a yellow pigment, was isolated from the healthy internal stem tissue of post-harvest cotton (Gossypium hirsutum, cultivar ‘DES-119’) grown at the Plant Breeding Unit at the E. V. Smith Research Center in Tallassee (Macon county), AL, USA. 16S rRNA gene sequence analysis of strain JM-1396T showed high sequence similarity values to the type strains of Novosphingobium mathurense, Novosphingobium panipatense (both 98.6 %) and Novosphingobium barchaimii (98.5 %); sequence similarities to all other type strains of species of the genus Novosphingobium were below 98.3 %. DNA–DNA pairing experiments of the DNA of strain JM-1396T and N. mathurense SM117T, N. panipatense SM16T and N. barchaimii DSM 25411T showed low relatedness values of 8 % (reciprocal 7 %), 24 % (reciprocal 26 %) and 19 % (reciprocal 25 %), respectively. Ubiquinone Q-10 was detected as the dominant quinone; the fatty acids C18 : 1ω7c (71.0 %) and the typical 2-hydroxy fatty acid, C14 : 0 2-OH (11.7 %), were detected as typical components. The polar lipid profile contained the diagnostic lipids diphosphatidylglycerol, phosphatidylethanolamine, sphingoglycolipid and phosphatidylcholine. The polyamine pattern contained the major compound spermidine and only minor amounts of other polyamines. All these data revealed that strain JM-1396T represents a novel species of the genus Novosphingobium. For this reason we propose the name Novosphingobium gossypii sp. nov. with the type strain JM-1396T ( = LMG 28605T = CCM 8569T = CIP 110884T).

scholarly journals Glucagon Receptor Signaling and Glucagon Resistance

2019 ◽  
Vol 20 (13) ◽  
pp. 3314 ◽  
Author(s):  
Janah ◽  
Kjeldsen ◽  
Galsgaard ◽  
Winther-Sørensen ◽  
Stojanovska ◽  
...  
Keyword(s):  
Lipid Metabolism ◽  
Amino Acid ◽  
Amino Acid Metabolism ◽  
Acid Metabolism ◽  
Metabolic Diseases ◽  
Physiological Role ◽  
Glucagon Receptor ◽  
Metabolomic Profiling ◽  
Hepatic Fat

Hundred years after the discovery of glucagon, its biology remains enigmatic. Accurate measurement of glucagon has been essential for uncovering its pathological hypersecretion that underlies various metabolic diseases including not only diabetes and liver diseases but also cancers (glucagonomas). The suggested key role of glucagon in the development of diabetes has been termed the bihormonal hypothesis. However, studying tissue-specific knockout of the glucagon receptor has revealed that the physiological role of glucagon may extend beyond blood-glucose regulation. Decades ago, animal and human studies reported an important role of glucagon in amino acid metabolism through ureagenesis. Using modern technologies such as metabolomic profiling, knowledge about the effects of glucagon on amino acid metabolism has been expanded and the mechanisms involved further delineated. Glucagon receptor antagonists have indirectly put focus on glucagon’s potential role in lipid metabolism, as individuals treated with these antagonists showed dyslipidemia and increased hepatic fat. One emerging field in glucagon biology now seems to include the concept of hepatic glucagon resistance. Here, we discuss the roles of glucagon in glucose homeostasis, amino acid metabolism, and lipid metabolism and present speculations on the molecular pathways causing and associating with postulated hepatic glucagon resistance.

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