Blar i forfatter Artikler, rapporter og annet (kjemi) "Leiros, Ingar"

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    • Biochemical and structural characterisation of a family GH5 cellulase from endosymbiont of shipworm P. megotara 

      Junghare, Madan; Manavalan, Tamilvendan; Fredriksen, Lasse; Leiros, Ingar; Altermark, Bjørn; Eijsink, Vincent; Vaaje-Kolstad, Gustav (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-04-04)
      Background Cellulases play a key role in the enzymatic conversion of plant cell-wall polysaccharides into simple and economically relevant sugars. Thus, the discovery of novel cellulases from exotic biological niches is of great interest as they may present properties that are valuable in the biorefning of lignocellulosic biomass. Results We have characterized a glycoside hydrolase 5 (GH5) domain ...

    • Biochemical characterization of ferric uptake regulator (Fur) from Aliivibrio salmonicida. Mapping the DNA sequence specificity through binding studies and structural modelling 

      Berg, Kristel; Pedersen, Hege Lynum; Leiros, Ingar (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-09)
      Iron is an essential nutrient for bacteria, however its propensity to form toxic hydroxyl radicals at high intracellular concentrations, requires its acquisition to be tightly regulated. Ferric uptake regulator (Fur) is a metal-dependent DNA-binding protein that acts as a transcriptional regulator in maintaining iron metabolism in bacteria and is a highly interesting target in the design of new ...

    • Biochemical characterization of ParI, an orphan C5-DNA methyltransferase from Psychrobacter arcticus 273-4 

      Grgic, Miriam; Williamson, Adele Kim; Bjerga, Gro Elin Kjæreng; Altermark, Bjørn; Leiros, Ingar (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-25)
      <p>Cytosine-specific DNA methyltransferases are important enzymes in most living organisms. In prokaryotes, most DNA methyltransferases are members of the type II restriction-modification system where they methylate host DNA, thereby protecting it from digestion by the accompanying restriction endonucleases. DNA methyltransferases can also act as solitary enzymes having important roles in controlling ...

    • Characterization of an intertidal zone metagenome oligoribonuclease and the role of the intermolecular disulfide bond for homodimer formation and nuclease activity 

      Piotrowski, Yvonne; Berg, Kristel; Klebl, David Paul; Leiros, Ingar; Larsen, Atle Noralf (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-08-17)
      The gene encoding MG Orn has been identified from a metagenomic library created from the intertidal zone in Svalbard and encodes a protein of 184 amino acid residues. The <i>mg orn</i> gene has been cloned, recombinantly expressed in <i>Escherichia coli</i>, and purified to homogeneity. Biochemical characterization of the enzyme showed that it efficiently degrades short RNA oligonucleotide substrates ...

    • The complex structures of isocitrate dehydrogenase from Clostridium thermocellum and Desulfotalea psychrophila support a new active site locking mechanism 

      Leiros, Hanna-Kirsti S.; Fedøy, Anita-Elin; Leiros, Ingar; Steen, Ida Helene (Journal article; Tidsskriftartikkel; Peer reviewed, 2012-07-07)
      Isocitrate dehydrogenase (IDH) catalyzes the oxidative NAD(P)+ -dependent decarboxylation of isocitrate into a-ketoglutarate and CO2 and is present in organisms spanning the biological range of temperature. We have solved two crystal structures of the thermophilic Clostridium thermocellum IDH (CtIDH), a native open apo CtIDH to 2.35 Å and a quaternary complex of CtIDH with NADP+ , isocitrate and ...

    • The crystal structure of the tetrameric DABA-aminotransferase EctB, a rate-limiting enzyme in the ectoine biosynthesis pathway 

      Hillier, Heidi Therese; Altermark, Bjørn; Leiros, Ingar (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-29)
      L‐2,4‐diaminobutyric acid (DABA) aminotransferases can catalyze the formation of amines at the distal ω‐position of substrates, and is the intial and rate‐limiting enzyme in the biosynthesis pathway of the cytoprotecting molecule (S)‐2‐methyl‐1,4,5,6‐tetrahydro‐4‐pyrimidine carboxylic acid (ectoine). Although there is an industrial interest in the biosynthesis of ectoine, the DABA aminotransferases ...

    • Discovery and characterization of a thermostable two-domain GH6 endoglucanase from a compost metagenome 

      Jensen, Marianne Slang; Fredriksen, Lasse; Mackenzie, Alasdair; Pope, Phillip; Leiros, Ingar; Chylenski, Piotr; Williamson, Adele Kim; Christopeit, Tony; Østby, Heidi; Vaaje-Kolstad, Gustav; Eijsink, Vincent (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-05-24)
      Enzymatic depolymerization of recalcitrant polysaccharides plays a key role in accessing the renewable energy stored within lignocellulosic biomass, and natural biodiversities may be explored to discover microbial enzymes that have evolved to conquer this task in various environments. Here, a metagenome from a thermophilic microbial community was mined to yield a novel, thermostable cellulase, named ...

    • The escherichia coli alkA gene is activated to alleviate mutagenesis by an oxidized deoxynucleoside 

      Grøsvik, Kristin; Tesfahun, Almaz Nigatu; Muruzábal-Lecumberri, Izaskun; Haugland, Gyri Teien; Leiros, Ingar; Ruoff, Peter; Kvaløy, Jan Terje; Knævelsrud, Ingeborg; Ånensen, Hilde; Alexeeva, Marina; Sato, Kousuke; Matsuda, Akira; Alseth, Ingrun; Klungland, Arne; Bjelland, Svein (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-02-25)
      The cellular methyl donor S-adenosylmethionine (SAM) and other endo/exogenous agents methylate DNA bases non-enzymatically into products interfering with replication and transcription. An important product is 3-methyladenine (m<sup>3</sup>A), which in <i>Escherichia coli</i> is removed by m<sup>3</sup>A-DNA glycosylase I (Tag) and II (AlkA). The <i>tag</i> gene is constitutively expressed, while ...

    • Intrinsic Strand-Incision Activity of Human UNG: Implications for Nick Generation in Immunoglobulin Gene Diversification 

      Alexeeva, Marina; Moen, Marivi Nabong; Xu, Xiang Ming; Rasmussen, Anette; Leiros, Ingar; Kirpekar, Finn; Klungland, Arne; Alsøe, Lene; Nilsen, Hilde; Bjelland, Svein (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-12-22)
      Uracil arises in cellular DNA by cytosine (C) deamination and erroneous replicative incorporation of deoxyuridine monophosphate opposite adenine. The former generates C ! thymine transition mutations if uracil is not removed by uracil-DNA glycosylase (UDG) and replaced by C by the base excision repair (BER) pathway. The primary human UDG is hUNG. During immunoglobulin gene diversification in ...

    • Mutational analysis of the pro-peptide of a marine intracellular subtilisin protease supports its role in inhibition 

      Bjerga, Gro Elin Kjæreng; Larsen, Øivind; ARSIN, Hasan; Williamson, Adele Kim; Garcia-Moyano, Antonio; Leiros, Ingar; Puntervoll, Pål (Journal article; Tidsskriftartikkel, 2018-06-16)
      Intracellular subtilisin proteases (ISPs) have important roles in protein processing during the stationary phase in bacteria. Their unregulated protein degrading activity may have adverse effects inside a cell, but little is known about their regulatory mechanism. Until now, ISPs have mostly been described from <i>Bacillus</i> species, with structural data from a single homolog. Here, we study a ...

    • Properties and distribution of a metallo-β-lactamase (ALI-1) from the fish pathogen Aliivibrio salmonicida LFI1238 

      Kristiansen, Anders; Grgic, Miriam; Altermark, Bjørn; Leiros, Ingar (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
      Objectives. To characterize the chromosome-encoded metallo-β-lactamase (MBL) from the psychrophilic, marine fish-pathogenic bacterium Aliivibrio salmonicida LFI1238 and check for the presence of the gene in other Aliivibrio isolates both connected to the fish-farming industry and from the environment. Methods. The MBL gene was cloned and intracellularly expressed in Escherichia coli. Kinetic ...

    • Structure determination of uracil-DNA N-glycosylase from Deinococcus radiodurans in complex with DNA 

      Pedersen, Hege Lynum; Johnson, Kenneth; McVey, Colin; Leiros, Ingar; Moe, Elin (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-01)

    • Temperature adaptation of DNA ligases from psychrophilic organisms 

      Berg, Kristel; Leiros, Ingar; Williamson, Adele Kim (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-03-02)
      DNA ligases operating at low temperatures have potential advantages for use in biotechnological applications. For this reason, we have characterized the temperature optima and thermal stabilities of three minimal Lig E-type ATP-dependent DNA ligase originating from Gram-negative obligate psychrophilic bacteria. The three ligases, denoted Vib-Lig, Psy-Lig, and Par-Lig, show a remarkable range of ...