Search results for "Transferases"

Characterization of a novel selenium methyltransferase from freshwater bacteria showing strong similarities with the calicheamicin methyltransferase

2004

A novel group of Se-methyltransferases is presented. The genetic determinant, named mmtA, which revealed this group was isolated from selenite and selenate-resistant freshwater bacteria. E. coli expressing mmtA and grown with a Se supplement emitted dimethyl selenide (DMSe) and dimethyl diselenide (DMDSe). Phylogenetic analysis divided MmtA-like bacterial sequences into two clusters, one grouping MmtA with S- and O-methyltransferases, and one grouping UbiE C-methyltransferases. Se methylation by some of these MmtA phyletic neighbours was investigated.

Cyclopropane Fatty Acid Synthase from Oenococcus oeni: Expression in Lactococcus lactis subsp. Cremoris and Biochemical Characterization

2015

Bacterial cyclopropane fatty acid synthases (CFA synthases) catalyze the transfer of a methyl group from S-adenosyl-L-methionine (AdoMet) to the double bond of a lipid chain, thereby forming a cyclopropane ring. CFAs contribute to resistance to acidity, dryness, and osmotic imbalance in many bacteria. This work describes the first biochemical characterization of a lactic acid bacterium CFA synthase. We have overexpressed Oenococcus oeni CFA synthase in E. coli in order to purify the enzyme. The optimum cyclopropanation activity was obtained at pH 5.6 and 35.8 °C. The high K(m) (AdoMet) value obtained (2.26 mM) demonstrates the low affinity of O. oeni enzyme toward the L. lactis subsp. cremo…

Tracing the origin of the compensasome: evolutionary history of DEAH helicase and MYST acetyltransferase gene families.

2001

Dosage compensation in Drosophila is mediated by a complex of proteins and RNAs called the "compensasome." Two of the genes that encode proteins of the complex, maleless (mle) and males-absent-on-the-first (mof), respectively, belong to the DEAH helicase and MYST acetyltransferase gene families. We performed comprehensive phylogenetic and structural analyses to determine the evolutionary histories of these two gene families and thus to better understand the origin of the compensasome. All of the members of the DEAH and MYST families of the completely sequenced Saccharomyces cerevisiae and Caenorhabditis elegans genomes, as well as those so far (June 2000) found in Drosophila melanogaster (f…

5-Azacytidine Inhibits the Activation of Senescence Program and Promotes Cytotoxic Autophagy during Trdmt1-Mediated Oxidative Stress Response in Insu…

2022

5-Azacytidine (5-azaC), a methyltransferase inhibitor and anticancer drug, can promote several cellular stress responses such as apoptosis, autophagy, and senescence. The action of 5-azaC is complex and can be modulated by dose, time of treatment, and co-administration with oxidants. Insulinoma is a rare pancreatic neuroendocrine tumor with limited chemotherapeutic options. In the present study, two cellular models of insulinoma were considered, namely NIT-1 and β-TC-6 mouse cells, to evaluate the effects of 5-azaC post-treatment during hydrogen peroxide-induced oxidative stress. 5-azaC attenuated the development of oxidant-induced senescent phenotype in both cell lines. No pro-apoptotic ac…

Effect of substituted phenols on transaminase activity in the fish,Leuciscus idus melanotus L.

1986

MiR-221 promotes stemness of breast cancer cells by targeting DNMT3b

2016

// Giuseppina Roscigno 1, 2 , Cristina Quintavalle 1, 2 , Elvira Donnarumma 3 , Ilaria Puoti 1 , Angel Diaz-Lagares 4 , Margherita Iaboni 1 , Danilo Fiore 1 , Valentina Russo 1 , Matilde Todaro 5 , Giulia Romano 6 , Renato Thomas 7 , Giuseppina Cortino 7 , Miriam Gaggianesi 5 , Manel Esteller 4 , Carlo M. Croce 6 , Gerolama Condorelli 1, 2 1 Department of Molecular Medicine and Medical Biotechnology, “Federico II” University of Naples, Naples, Italy 2 IEOS-CNR, Naples, Italy 3 IRCCS-SDN, Naples, Italy 4 Epigenetic and Cancer Biology Program (PEBC) IDIBELL, Hospital Duran I Reynals, Barcelona, Spain 5 Department of Surgical and Oncological Sciences, Cellular and Molecular Pathophysiology Lab…

Kinetic properties of a nucleoside phosphotransferase of chick embryo

1981

1. A nonspecific nucleoside phosphotransferase (nucleotide : 3'-deoxynucleotide 5'-phosphotransferase, EC 2.7.1.77), purified from chick embryos, catalyzes the transfer of phosphate ester from a nucleotide donor to a nucleoside acceptor. 2. The enzyme exhibits sigmoidal kinetics with respect to nucleoside monophosphate donors, but with respect to nucleoside di- or triphosphate donors and nucleoside acceptors hyperbolic kinetics were obtained. 3. The nucleoside phosphotransferase of chick embryo is unstable to heat and is protected from inactivation by a large number of nucleosides. 4. Nucleoside di- and triphosphates lower both the concentration of nucleoside monophosphates required for hal…

Interrelationships between Growth Yield, ATPase and Adenylate Kinase Activities inZymomonas mobilis

2001

The presence of cytoplasmic and membrane-bound adenylate kinase (EC 2.7,4.3) as well as inorganic pyrophosphatase (EC 3.6.1.1) was detected in Zymomonas mobilis ATCC 29191. An increase in the molar growth yield (Y X/S ) of Z. mobilis under aerobic growth conditions appeared to be in proportion to a reduction of membrane-bound adenylate kinase (mAK) and ATPase activities and to an increase in cytoplasmic adenylate kinase (AK) activity. Significant (1 - P < 0.01) multiple regressions were observed between the values of Y x (dependent variable), ATPase and AK or AK and mAK as independent variables, suggesting that a combined operation of these phosphohydrolases and phosphotransferases would be…

A newin vitroapproach for the simultaneous determination of phase I and phase II enzymatic activities of human hepatocyte preparations

2007

Primary hepatocytes are still the best qualified in vitro system to anticipate drug metabolism in man. Recent advances in hepatocytes cryopreservation have notably increased their use not only for drug metabolism studies, but also for other applications such as cell transplantation. Evaluation of the drug-metabolizing competence of each hepatocytes preparation is needed. To date, the metabolic characterization of hepatocytes preparations relies on the assessment of phase I activities and the role of phase II enzymes receives little attention. A novel approach for the rapid assessment of the metabolic functionality of hepatocytes has been developed. A five-probe cocktail was used to simultan…

Identification of the 3-amino-3-carboxypropyl (acp) transferase enzyme responsible for acp3U formation at position 47 in Escherichia coli tRNAs

2019

AbstracttRNAs from all domains of life contain modified nucleotides. However, even for the experimentally most thoroughly characterized model organism Escherichia coli not all tRNA modification enzymes are known. In particular, no enzyme has been found yet for introducing the acp3U modification at position 47 in the variable loop of eight E. coli tRNAs. Here we identify the so far functionally uncharacterized YfiP protein as the SAM-dependent 3-amino-3-carboxypropyl transferase catalyzing this modification and thereby extend the list of known tRNA modification enzymes in E. coli. Similar to the Tsr3 enzymes that introduce acp modifications at U or m1Ψ nucleotides in rRNAs this protein conta…