• Antibiotikaresistent - hva nå? 

      Leiros, Hanna-Kirsti S. (Conference object; Konferansebidrag, 2010-09-02)
    • The autoinducer synthases LuxI and AinS are responsible for temperature-dependent AHL production in the fish pathogen Aliivibrio salmonicida 

      Hansen, Hilde; Purohit, Amit Anand; Leiros, Hanna-Kirsti S.; Johansen, Jostein; Kellermann, Stefanie J.; Bjelland, Ane Mohn; Willassen, Nils Peder (Journal article; Tidsskriftartikkel, 2015-03-24)
      Background: Quorum sensing (QS) is a cell-to-cell communication system used by bacteria to regulate activities such as virulence, bioluminescence and biofilm formation. The most common QS signals in Gram-negative bacteria are N-acyl-homoserine lactones (AHLs). Aliivibrio salmonicida is the etiological agent of cold water vibriosis in Atlantic salmon, a disease which occurs mainly during seasons ...
    • 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 ...
    • Cryptic β-Lactamase Evolution Is Driven by Low β-Lactam Concentrations 

      Fröhlich, Christopher; Gama, João Alves; Harms, Klaus; Hirvonen, Viivi H. A.; Lund, Bjarte Aarmo; van der Kamp, Marc W.; Johnsen, Pål Jarle; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-04-28)
      Our current understanding of how low antibiotic concentrations shape the evolution of contemporary β-lactamases is limited. Using the widespread carbapenemase OXA-48, we tested the long-standing hypothesis that selective compartments with low antibiotic concentrations cause standing genetic diversity that could act as a gateway to developing clinical resistance. Here, we subjected <i>Escherichia ...
    • Crystal Structures of Pseudomonas aeruginosa GIM-1: Active-Site Plasticity in Metallo-beta-Lactamases 

      Borra, Naga Pardha Saradhi; Samuelsen, Ørjan; Spencer, James; Walsh, Timothy R.; Lorentzen, marit sjo; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Metallo- -lactamases (MBLs) have rapidly disseminated worldwide among clinically important Gram-negative bacteria and have challenged the therapeutic use of -lactam antibiotics, particularly carbapenems. The blaGIM-1 gene, encoding one such enzyme, was first discovered in a Pseudomonas aeruginosa isolate from 2002 and has more recently been reported in Enterobacteriaceae. Here, we present crystal ...
    • Discovery of Novel Inhibitor Scaffolds against the Metallo-beta-lactamase VIM-2 by Surface Plasmon Resonance (SPR) Based Fragment Screening 

      Christopeit, Tony; Carlsen, Trine Josefine Olsen; Helland, Ronny; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-10-17)
      Metallo-β-lactamase (MBL) inhibitors can restore the function of carbapenem antibiotics and therefore help to treat infections of antibiotic resistant bacteria. In this study, we report novel fragments inhibiting the clinically relevant MBL Verona integron-encoded metallo-β-lactamase (VIM-2). The fragments were identified from a library of 490 fragments using an orthogonal screening approach based ...
    • Dissemination and Characteristics of a Novel Plasmid-Encoded Carbapenem-Hydrolyzing Class D β-Lactamase, OXA-436, Found in Isolates from Four Patients Involving Six Different Hospitals in Denmark. 

      Samuelsen, Ørjan; Hansen, Frank; Aasnæs, Bettina; Hasman, Henrik; Lund, Bjarte Aarmo; Leiros, Hanna-Kirsti S.; Lilje, Berit; Janice, Jessin; Jakobsen, Lotte; Littauer, Pia; Søes, Lillian M; Holzknecht, Barbara J.; Andersen, Leif P; Stegger, Marc; Andersen, Paal S.; Hammerum, Anette M. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-23)
      The diversity of OXA-48-like carbapenemases are continually expanding. In this study, we describe the dissemination and characteristics of a novel class D carbapenemase (CHDL) named OXA-436. In total, six OXA-436-producing Enterobacteriaceae isolates including Enterobacter asburiae (n=3), Citrobacter freundii (n=2) and Klebsiella pneumoniae (n=1) were identified in four patients in the period between ...
    • DNA binding with a minimal scaffold: structure-function analysis of Lig E DNA ligases 

      Williamson, Adele Kim; Grgic, Miriam; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-07-11)
      DNA ligases join breaks in the phosphodiester backbone of DNA by catalysing the formation of bonds between opposing 5′P and 3′OH ends in an adenylation-dependent manner. Catalysis is accompanied by reorientation of two core domains to provide access to the active site for cofactor utilization and enable substrate binding and product release. The general paradigm is that DNA ligases engage their DNA ...
    • Enzyme-adenylate structure of a bacterial ATP-dependent DNA ligase with a minimized DNA-binding surface 

      Williamson, Adele Kim; Rothweiler, Ulli; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-11-01)
      DNA ligases are a structurally diverse class of enzymes which share a common catalytic core and seal breaks in the phosphodiester backbone of double-stranded DNA via an adenylated intermediate. Here, the structure and activity of a recombinantly produced ATP-dependent DNA ligase from the bacterium Psychromonas sp. strain SP041 is described. This minimal-type ligase, like its close homologues, ...
    • Exploring the role of L209 residue in the active site of NDM-1 a metallo-β-lactamase 

      Marcoccia, Francesca; Leiros, Hanna-Kirsti S.; Aschi, Massimiliano; Amicosante, Gianfranco; Perilli, Mariagrazia (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-01-02)
      Background:<br> New Delhi Metallo-β-Lactamase (NDM-1) is one of the most recent additions to the β-lactamases family. Since its discovery in 2009, NDM-1 producing Enterobacteriaceae have disseminated globally. With few effective antibiotics against NDM-1 producers, there is an urgent need to design new drug inhibitors through the help of structural and mechanistic information available from ...
    • Fluorinated captopril analogues inhibit metallo-β-lactamases and facilitate structure determination of NDM-1 binding pose 

      Kondratieva, Alexandra; Palica, Katarzyna; Frøhlich, Christopher; Rolfsnes Hovd, Rebekka; Leiros, Hanna-Kirsti S.; Erdélyi, Máté; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2024-01-10)
      Bacterial resistance to the majority of clinically used β-lactam antibiotics is a global health threat and, consequently, the driving force for the development of metallo-β-lactamase (MBL) inhibitors. The rapid evolution of new MBLs calls for new strategies and tools for inhibitor development. In this study, we designed and developed a series of trifluoromethylated captopril analogues as probes for ...
    • A focused fragment library targeting the antibiotic resistance enzyme - Oxacillinase-48: Synthesis, structural evaluation and inhibitor design 

      Ahkter, Sundus; Lund, Bjarte Aarmo; Ismael, Aya; Langer, Manuel; Isaksson, Johan; Christopeit, Tony; Leiros, Hanna-Kirsti S.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-10)
      β-Lactam antibiotics are of utmost importance when treating bacterial infections in the medical community. However, currently their utility is threatened by the emergence and spread of β-lactam resistance. The most prevalent resistance mechanism to β-lactam antibiotics is expression of β-lactamase enzymes. One way to overcome resistance caused by β-lactamases, is the development of β-lactamase ...
    • A high-throughput, restriction-free cloning and screening strategy based on ccdB-gene replacement 

      Bjerga, Gro Elin Kjæreng; Lund, Bjarte Aarmo; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
      Background In high-throughput demanding fields, such as biotechnology and structural biology, molecular cloning is an essential tool in obtaining high yields of recombinant protein. Here, we address recently developed restriction-free methods in cloning, and present a more cost-efficient protocol that has been optimized to improve both cloning and clone screening. Results In our case study, ...
    • Initial characterization of an iron superoxide dismutase from Thermobifida fusca 

      Hamre, Anne Grethe; Al-Sadawi, Rim; Johannesen, Kirsti Merete; Bisarro, Bastien; Kjendseth, Åsmund Røhr; Leiros, Hanna-Kirsti S.; Sørlie, Morten (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-19)
      Superoxide dismutases (SODs) are enzymes that catalyze the dismutation of the superoxide radical anion into O<sup>2</sup> and H<sup>2</sup>O<sup>2</sup> in a two-step reaction. They are ubiquitous to all forms of life and four different types of metal centers are detected, dividing this class of enzymes into Cu-/Zn-, Ni-, Mn-, and Fe-SODs. In this study, a superoxide dismutase from the ...
    • Investigating the role of residues W228 and Y233 in the structure and activity of the GIM-1 metallo-beta-lactamase. 

      Skagseth, Susann; Carlsen, Trine Josefine Olsen; Bjerga, Gro Elin Kjæreng; Spencer, James; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-12-07)
      Metallo--lactamases (MBLs) hydrolyze virtually all -lactam antibiotics, including penicillins, cephalosporins, and carbapenems. The worldwide emergence of antibiotic-resistant bacteria harboring MBLs poses an increasing clinical threat. The MBL German imipenemase-1 (GIM-1) possesses an active site that is narrower and more hydrophobic than the active sites of other MBLs. The GIM-1 active-site ...
    • Metallo-β-Lactamase Inhibitor Phosphonamidate Monoesters 

      Palica, Katarzyna; Vorácová, Manuela; Skagseth, Susann; Andersson Rasmussen, Anna; Allander, Lisa; Hubert, Madlen; Sandegren, Linus; Leiros, Hanna-Kirsti S.; Andersson, Hanna; Erdélyi, Máté (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-01-25)
      Being the second leading cause of death and the leading cause of disability-adjusted life years worldwide, infectious diseases remain-contrary to earlier predictions-a major consideration for the public health of the 21st century. Resistance development of microbes to antimicrobial drugs constitutes a large part of this devastating problem. The most widely spread mechanism of bacterial resistance ...
    • Metallo-β-lactamase inhibitors by bioisosteric replacement: preparation, activity and binding 

      Skagseth, Susann; Akhter, Sundus; Paulsen, Marianne H; Muhammad, Zeeshan; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S.; Bayer, Annette (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-14)
      Bacterial resistance is compromising the use of β-lactam antibiotics including carbapenems. The main resistance mechanism against β-lactams is hydrolysis of the β-lactam ring mediated by serine- or metallo-β-lactamases (MBLs). Although several inhibitors of MBLs have been reported, none has been developed into a clinically useful inhibitor. Mercaptocarboxylic acids are among the most prominent ...
    • MutT from the fish pathogen Aliivibrio salmonicida is a cold active nucleotide pool sanitization enzyme with an unexpected high thermostability 

      Lian, Kjersti; Leiros, Hanna-Kirsti S.; Moe, Elin (Journal article; Tidsskriftartikkel; Peer reviewed, 2015)
    • Presence of acyl-homoserine lactones in 57 members of the Vibrionaceae family 

      Purohit, Amit Anand; Johansen, Jostein a; Hansen, Hilde; Leiros, Hanna-Kirsti S.; Kashulin, Alexander; Karlsen, Christian; Smalås, Arne O.; Haugen, Peik; Willassen, Nils Peder (Journal article; Tidsskriftartikkel; Peer reviewed, 2013-05-31)
      Aims: The aim of this study was to use a sensitive method to screen and quantify 57 Vibrionaceae strains for the production of acyl-homoserine lactones (AHLs) and map the resulting AHL profiles onto a host phylogeny.<p> <p>Methods and Results: We used a high-performance liquid chromatography– tandem mass spectrometry (HPLC-MS/MS) protocol to measure AHLs in spent media after bacterial growth. ...
    • Screening and Design of Inhibitor Scaffolds for the Antibiotic Resistance Oxacillinase-48 (OXA-48) through Surface Plasmon Resonance Screening 

      Lund, Bjarte Aarmo; Christopeit, Tony; Guttormsen, Yngve; Bayer, Annette; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-05-11)
      The spread of antibiotic resistant bacteria is a global threat that shakes the foundations of modern healthcare. β-Lactamases are enzymes that confer resistance to β-lactam antibiotics in bacteria, and there is a critical need for new inhibitors of these enzymes for combination therapy together with an antibiotic. With this in mind, we have screened a library of 490 fragments to identify starting ...