• Structural and biochemical characterization of the environmental MBLs MYO-1, ECV-1 and SHD-1 

      Frøhlich, Christopher; Sørum, Vidar; Huber, Sandra; Samuelsen, Ørjan; Berglund, Fanny; Kristiansson, Erik; Kotsakis, Stathis D.; Marathe, Nachiket P.; Larsson, Joakim; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-28)
      <i>Background</i> - MBLs form a large and heterogeneous group of bacterial enzymes conferring resistance to β-lactam antibiotics, including carbapenems. A large environmental reservoir of MBLs has been identified, which can act as a source for transfer into human pathogens. Therefore, structural investigation of environmental and clinically rare MBLs can give new insights into structure–activity ...
    • Structural and biochemical characterization of VIM-26 shows that Leu224 has implications for the substrate specificity of VIM metallo-β-lactamases 

      Leiros, Hanna-Kirsti S.; Edvardsen, Kine Susann Waade; Bjerga, Gro Elin Kjæreng; Samuelsen, Ørjan (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-02-06)
      During the last decades antimicrobial resistance has become a global health problem. Metallo-β-lactamases (MBLs) which are broad-spectrum β-lactamases that inactivate virtually all β-lactams including carbapenems, are contributing to this health problem. In this study a novel MBL variant, termed VIM-26, identified in a Klebsiella pneumoniae isolate was studied. VIM-26 belongs to the Verona ...
    • Structural and biophysical analysis of interactions between cod and human uracil-DNA N-glycosylase (UNG) and UNG inhibitor (Ugi) 

      Assefa, Netsanet Gizaw; Niiranen, Laila; Johnson, Kenneth; Leiros, Hanna-Kirsti S.; Smalås, Arne O.; Willassen, Nils Peder; Moe, Elin (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-07-25)
      Uracil-DNA N-glycosylase from Atlantic cod (cUNG) shows cold-adapted features such as high catalytic efficiency, a low temperature optimum for activity and reduced thermal stability compared with its mesophilic homologue human UNG (hUNG). In order to understand the role of the enzyme–substrate interaction related to the cold-adapted properties, the structure of cUNG in complex with a bacteriophage ...
    • Structural and thermodynamic insight into phenylalanine hydroxylase from the human pathogen Legionella pneumophila 

      Leiros, Hanna-Kirsti S.; Flydal, Marte Innselset; Martinez, Aurora (Journal article; Tidsskriftartikkel; Peer reviewed, 2013)
      Phenylalanine hydroxylase from Legionella pneumophila (lpPAH) has a major functional role in the synthesis of the pigment pyomelanin, which is a potential virulence factor. We present here the crystal structure of lpPAH, which is a dimeric enzyme that shows high thermostability, with a midpoint denat- uration temperature of 79 ◦C, and low substrate affinity. The structure revealed a dimerization ...
    • Structural insight into DNA joining: from conserved mechanisms to diverse scaffolds 

      Williamson, Adele Kim; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-04)
      DNA ligases are diverse enzymes with essential functions in replication and repair of DNA; here we review recent advances in their structure and distribution and discuss how this contributes to understanding their biological roles and technological potential. Recent high-resolution crystal structures of DNA ligases from different organisms, including DNA-bound states and reaction intermediates, have ...
    • Structural insight into DNA joining: from conserved mechanisms to diverse scaffolds 

      Williamson, Adele Kim; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-04)
      DNA ligases are diverse enzymes with essential functions in replication and repair of DNA; here we review recent advances in their structure and distribution and discuss how this contributes to understanding their biological roles and technological potential. Recent high-resolution crystal structures of DNA ligases from different organisms, including DNA-bound states and reaction intermediates, have ...
    • Structural insights into the enhanced carbapenemase efficiency of OXA-655 compared to OXA-10 

      Leiros, Hanna-Kirsti S.; Thomassen, Ane Molden; Samuelsen, Ørjan; Flach, Carl-Fredrik; Kotsakis, Stathis D.; Larsson, Joakim (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-07-19)
      Carbapenemases are the main cause of carbapenem resistance in Gram‐negative bacteria. How β‐lactamases with weak carbapenemase activity, such as the OXA‐10‐type class D β‐lactamases, contribute to anti‐bacterial drug resistance is unclear. OXA‐655 is a T26M and V117L OXA‐10 variant, recently identified from hospital wastewater. Despite exhibiting stronger carbapenemase activity towards ertapenem ...
    • Structural insights into TMB-1 and the role of residues 119 and 228 in substrate and inhibitor binding 

      Skagseth, Susann; Christopeit, Tony; Akhter, Sundus; Bayer, Annette; Samuelsen, Ørjan; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-05-30)
      Metallo-β-lactamases (MBLs) threaten the effectiveness of β-lactam antibiotics, including carbapenems, and are a concern for global public health. β-Lactam/β-lactamase inhibitor combinations active against class A and class D carbapenemases are used, but no clinically useful MBL inhibitor is currently available. Tripoli metallo-β-lactamase-1 (TMB-1) and TMB-2 are members of MBL subclass B1a, where ...
    • Structural intermediates of a DNA-ligase complex illuminate the role of the catalytic metal ion and mechanism of phosphodiester bond formation 

      Williamson, Adele Kim; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-07-17)
      DNA ligases join adjacent 5′ phosphate (5′P) and 3′ hydroxyl (3′OH) termini of double-stranded DNA via a three-step mechanism requiring a nucleotide cofactor and divalent metal ion. Although considerable structural detail is available for the first two steps, less is known about step 3 where the DNA-backbone is joined or about the cation role at this step. We have captured high-resolution structures ...
    • Structural studies of triazole inhibitors with promising inhibitor effects against antibiotic resistance metallo-β-lactamases 

      Muhammad, Zeeshan; Skagseth, Susann; Boomgaren, Marc; Akhter, Sundus; Frøhlich, Christopher; Ismael, Aya; Christopeit, Tony; Bayer, Annette; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-06-18)
      Metallo-β-lactamases (MBLs) are an emerging cause of bacterial antibiotic resistance by hydrolysing all classes of β-lactams except monobactams, and the MBLs are not inhibited by clinically available serine-β-lactamase inhibitors. Two of the most commonly encountered MBLs in clinical isolates worldwide – the New Delhi metallo-β-lactamase (NDM-1) and the Verona integron-encoded metallo-β-lactamase ...
    • The structure of the metallo-β-lactamase VIM-2 in complex with a triazolylthioacetamide inhibitor 

      Christopeit, Tony; Yang, Ke-Wu; Yang, Shao-Kang; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2016-11)
      The increasing number of pathogens expressing metallo-β-lactamases (MBLs), and in this way achieving resistance to β-lactam antibiotics, is a significant threat to global public health. A promising strategy to treat such resistant pathogens is the co-administration of MBL inhibitors together with β-lactam antibiotics. However, an MBL inhibitor suitable for clinical use has not yet been identified. ...
    • Structure, activity and thermostability investigations of OXA-163, OXA-181 and OXA-245 using biochemical analysis, crystal structures and differential scanning calorimetry analysis 

      Lund, Bjarte Aarmo; Thomassen, Ane Molden; Carlsen, Trine Josefine Olsen; Leiros, Hanna-Kirsti S. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017)
      The first crystal structures of the class D β-lactamases OXA-181 and OXA-245 were determined to 2.05 and 2.20 Å resolution, respectively; in addition, the structure of a new crystal form of OXA-163 was resolved to 2.07 Å resolution. All of these enzymes are OXA-48-like and have been isolated from different clinical Klebsiella pneumoniae strains and also from other human pathogens such as Pseudomonas ...
    • Synthesis and biological evaluation of new dipicolylamine zinc chelators as metallo-β-lactamase inhibitors 

      Prandina, Anthony; Radix, Sylvie; Le Borgne, Marc; Jordheim, Lars Petter; Bousfiha, Zineb; Fröhlich, Christopher; Leiros, Hanna-Kirsti S.; Samuelsen, Ørjan; Frøvold, Espen; Rongved, Pål; Åstrand, Ove Alexander Høgmoen (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-02-02)
      Antibiotics are key drugs in modern healthcare, especially in hospitals, where multiresistant bacteria resides and is a potential threat to human health. In the present work, a new series of adjuvants working synergistically with the carbapenem meropenem, in which a selective zinc-chelating agent was covalently linked to the small bacterial peptide D-Ala-D-Ala, was synthesized and tested against ...
    • Synthetic cationic antimicrobial peptides bind with their hydrophobic parts to drug site II of human serum albumin 

      Sivertsen, Annfrid; Isaksson, Johan; Leiros, Hanna-Kirsti S.; Svenson, Johan; Svendsen, John Sigurd; Brandsdal, Bjørn Olav (Journal article; Tidsskriftartikkel; Peer reviewed, 2014)
    • ZN148 Is a Modular Synthetic Metallo-beta-Lactamase Inhibitor That Reverses Carbapenem Resistance in Gram-Negative Pathogens In Vivo 

      Samuelsen, Ørjan; Åstrand, Ove Alexander Høgmoen; Frøhlich, Christopher; Heikal, Adam; Skagseth, Susann; Carlsen, Trine Josefine Olsen; Leiros, Hanna-Kirsti S.; Bayer, Annette; Schnaars, Christian; Kildahl-andersen, Geir; Lauksund, Silje; Finke, Sarah; Huber, Sandra; Gjøen, Tor; Andresen, Adriana Magalhaes Santos; Økstad, Ole Andreas; Rongved, Pål (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-05-21)
      Carbapenem-resistant Gram-negative pathogens are a critical public health threat and there is an urgent need for new treatments. Carbapenemases (β-lactamases able to inactivate carbapenems) have been identified in both serine β-lactamase (SBL) and metallo-β-lactamase (MBL) families. The recent introduction of SBL carbapenemase inhibitors has provided alternative therapeutic options. Unfortunately, ...